IRRIGATION SCHEDULING

Using

REAL TIME SOIL MOISTURE MEASUREMENTS

A report on methods and procedures used by the Bureau of Reclamation’s

Lower Colorado Region to provide field irrigation scheduling during the time

period from about 1975 to about 1990

December 2003
Preface

The Bureau of Reclamation’s Lower Colorado Region (LC Region) was a pioneer in

developing the neutron moisture gauge and associated procedures for scheduling

irrigations. This report describes the procedures developed initially by Dr. Melvin

Campbell. Some of the techniques have since been refined through years of daily use

of the gauge for production irrigation scheduling by Reclamation, district, Bureau of

Indian Affairs, and Tribal staff. Individuals most closely involved with development

efforts have since transferred from the Lower Colorado Region or have retired. 

Therefore, resources of Reclamation’s Upper Colorado Region, headquartered in Salt

Lake City, Utah, have been used to prepare and produce this report. Three individuals

closely associated with development and use of the neutron moisture gauge have

contributed to the preparation of this report. They are: Stan Conway, Land Suitability

and Water Quality Group, Technical Service Center, Denver, Colorado; Michael Stuver,

Regional Water Management Coordinator, Upper Colorado Region, Salt Lake City,

Utah; and Terry Taylor, Soil Scientist, Retired, Dillingham, Alaska. The report was

compiled by Michael Stuver with material and editing provided by Stan Conway and

Terry Taylor. Completion of this report has been on a time-available basis and has

required several years to finish.

About This Report

This report describes how Reclamation provided field irrigation scheduling services in its

Lower Colorado Region during the time period from about 1975 to about 1990. It may

be helpful to organizations desiring to provide a field irrigation scheduling service. 

Chapter 1 gives some general background information. Chapter 2 discusses the theory

and procedure used to schedule irrigations using in-place field moisture measurements. 

Chapter 3 describes the equipment used to conduct field irrigation scheduling programs

in the LC Region. Chapter 4 discusses what is needed and describes how to begin a

field irrigation scheduling service. Finally, Chapter 5 describes the day-to-day activities

involved in providing a field irrigation scheduling service.
Table of Contents

i

TABLE OF CONTENTS

1 - INTRODUCTION ................................................... 1

2 - THEORY OF SCHEDULING IRRIGATIONS USING MOISTURE GAUGES ...... 4

How Irrigation Scheduling Works ..................................... 4

How Plant Stress is Determined . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3 - REQUIRED EQUIPMENT ........................................... 13

The Neutron Measuring Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Description of Gauge ......................................... 13

Use of Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Standardization Barrels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Infrared Thermometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Description of Thermometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Use of Thermometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Soil Auger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Access Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Access Tube Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

4 - GETTING STARTED ............................................... 24

Starting a New Field Irrigation Scheduling Service . . . . . . . . . . . . . . . . . . . . . . . 24

Calibrating Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Standardizing the Neutron Moisture Gauge . . . . . . . . . . . . . . . . . . . . . . . . 26

Establishing Well-Watered Baseline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

5 - SCHEDULING IRRIGATIONS ........................................ 31

Starting Irrigation Service to a New Field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Locating Access Tube Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Accessibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Irrigation Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Soil Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Crop Stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Installing Access Tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Determining Refill Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Using Optimum Moisture Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Using Crop Water Stress Index (CWSI) . . . . . . . . . . . . . . . . . . . . . . . 33

Using Observation of Visible Stress . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Using Farmer's Judgement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Establishing Full Point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Visiting Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Contacting Farmers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table of Contents

ii

LIST OF TABLES

Number Title Page

1 Terms and Definitions ...................................... 10

2 Well-Watered Base Line Coefficients for Selected Crops ........... 12

LIST OF FIGURES

1 Graphical Scheduling with Neutron Probe Measurements ........... 5

2 CWSI vs. Date for Wheat .................................... 7

3 Typical Vapor Pressure Deficit vs Temperature

 Depression Graph ........................................ 9

4 Foliage-Air Temperature vs. Vapor Pressure

 Deficit for Well-Watered Alfalfa ............................. 11

5 CPN Model 503 Moisture Gauge ............................. 14

6 Taking Moisture Readings With the 503 ........................ 15

7 Probe Rating Table - Uniform Count Increment .................. 16

8 Probe Rating Table - Uniform Water Content Increment ............ 17

 9 Gauge on Standardization Barrel ............................. 19

10 Infrared Thermometer ...................................... 19

 11 Measuring Turf Canopy Temperature with the Infrared Thermometer . 20

 12 Sample Plant Foliage Temperature Data ....................... 22

13 Access Tube Cap Assembly ................................. 23

14 Installing a Steel Access Tube Using the Access Tube Driver ....... 23

15 Soil Moisture in Inches per Foot vs. Count

 Ratio of the Neutron Moisture Gauge ........................ 27

16 Neutron Probe Standard Count Determination ................... 29

17 Sample Printout from Program VEGY .......................... 34

18 Data for CWSI Hand Calculation Example ...................... 35

19 Hand Calculating Crop Water Stress Index ...................... 36

20 Sample Field Graph ....................................... 38

21 Sample Farmer Report Form ................................ 40

22 Sample Computer Generated Farm Irrigation Schedule ............ 41

APPENDIX

A Relative Humidity, Percent - Centigrade Temperatures

B Vapor Pressure of Water Below 100 °C

C Equipment Drawings and Specifications

D Blank Field Data sheets

E Using Program VEGY
Chapter 1 - Introduction

1

FIELD IRRIGATION SCHEDULING

1 - INTRODUCTION

The efficient use of water is necessary in many areas to meet existing needs. In some

areas, extensive use of water for irrigation and the increasing need for municipal and

industrial water is depleting available supplies. In other areas there is an abundance of

water. Yet, the high cost of fertilizers and farm labor or the need to improve crop yields

and quality are causing the farmer to look for ways to improve on-farm irrigation

efficiency.

The Bureau of Reclamation began its involvement with on-farm field irrigation

scheduling when it began its Irrigation Management Service (IMS) in the early 1970's. 

IMS provided a staff of one or two specialists on-site to help local irrigation districts

establish an IMS. The local irrigation district also provided one or more employees. 

Reclamation intended to withdraw its IMS staff when the district’s staff was fully trained

and capable of continuing the IMS on its own. 

Reclamation’s Lower Colorado Region (LC Region) had been involved in the IMS

program from the early 1970's to the early 1990's. The LC Region continued to provide

technical support for several years after it discontinued active participation in local IMS

programs. This report describes the process of scheduling irrigations using field

moisture measurements that was adopted by the LC Region. The standard device for

taking these measurements was the neutron moisture gauge.

This report is based upon the LC Region’s efforts to provide field irrigation scheduling

services. It is intended to be used by Federal and State agencies, irrigation districts, or

private consultants that are supporting or providing an irrigation scheduling service. It

may also be helpful to private farmers who purchase their own gauges and provide their

own scheduling service. The report discusses procedures for starting a new service. 

Also, it describes the necessary equipment and how to use the equipment. Finally, it

describes the process for conducting field activities and communicating findings to the

farmer.

Improved on-farm efficiencies may require changes in present irrigation and water

delivery practices. The irrigator may need better information to help him know when to

irrigate a particular crop. Proper scheduling depends upon how much water is available

to the plant. It also depends upon how fast that plant or crop is using water. The farmer

must also know how much water to apply. This depends upon the amount of water

used by the crop, the distribution uniformity (irrigation efficiency) of the irrigation system,

the water holding capacity of the soil, and salt leaching requirements.

By using careful management and sound irrigation scheduling practices, the farmer can

realize the direct savings in water, fertilizer, pesticide, herbicide, and farm labor. In

addition, many farms have seen increases in quality and quantity of their yields.
Chapter 1 - Introduction

2

Although irrigation scheduling helps the farmer, irrigation districts usually provide the

scheduling service. Reclamation has, on occasion, also helped provide the service. In

a few instances, private consultants provide the service for a fee. Some large farms

buy their own equipment and provide their own service. Unless a farm is large,

however, most farmers cannot justify the cost of the equipment. In the LC Region,

Reclamation partnered with local irrigation districts and a Native American Tribe to

provide the services.

Services provided by an irrigation district are usually more economical than similar

services provided by a farmer. When a district provides the service, it spreads the cost

of equipment among many individuals and can better control the quality and accuracy of

the scheduling. Also, a district can better assess the success of its water management

activities when the field irrigation scheduling service is a part of its water management

program.

Districts have met the cost of the service in several ways. Some included the field

irrigation scheduling costs with other operating costs that are covered with a variety of

taxes and assessments. Other districts provided the service for a fee. Farmers paid a

fee based upon the number of acres or fields enrolled in the service. A fully equipped

district technician could easily serve several farms. Typically, a technician served about

5,000 acres when 40-acre fields were the norm.

The LC Region started its Water Management and Conservation (WMC) program in

1973. (In 1996, the WMC Program became officially known as the Water Conservation

Field Services Program (WCFSP) with little or no emphasis on providing field irrigation

scheduling with the neutron moisture gauge.) This was about the same time the

program was being introduced in other areas of the western United States. The

program was originally known as the Irrigation Management Service (IMS) and initially

provided field irrigation scheduling service to participating project water users. 

The IMS used a computer model to schedule irrigations. The model utilized used

weather data to compute crop water use and a soil water budget to determine timing

and amount of water to apply. The IMS computer programs were developed by

Reclamation's Technical Services Center (formerly known as the Engineering and

Research Center) staff for use on Reclamation's CYBER computer system. 

Participating projects accessed the CYBER with computer terminals and dedicated

telephone lines. Eventually, the IMS service was expanded to provide a gravity

distribution scheduling program. As Reclamation's IMS program expanded and

contemplated providing additional services, the program was renamed the Water

Management and Conservation Program.

The IMS Program was introduced simultaneously to three irrigation projects in the

LC Region. These were:

(1) Wellton-Mohawk Irrigation District, near Wellton, Arizona; 

(2) Palo Verde Irrigation District, near Blythe, California; and 

(3) Colorado River Indian Irrigation Project, at Poston (near Parker),
Chapter 1 - Introduction

3

 Arizona. 

All three IMS programs began using the IMS computer programs with varying degrees

of success. Three major problems became obvious. First, terminal connections with

the CYBER computer in Denver were unreliable. Second, the computer model would

not duplicate observed field conditions to an acceptable level of accuracy. Finally,

farmers lacked confidence in the IMS schedules. Farmers' lack of confidence caused

some sponsoring districts to consider dropping the programs.

To improve reliability and acceptability of the IMS programs, Reclamation specialists in

the LC Region worked with a company that manufactured neutron moisture/density

gauges for the construction industry. Together, they developed a neutron moisture

gauge suitable for measuring agricultural soil moisture content. Prototype models were

developed, tested in the field, and refined until models suitable for production field

scheduling were available. Procedures were then developed and implemented for

scheduling irrigations with the newly developed neutron moisture gauge (often called

the neutron probe). Eventually, use of the IMS programs on the CYBER computer was

discontinued by the LC Region in favor of the more precise method of scheduling

irrigations with the neutron moisture gauge.

The procedures and techniques described here have been used successfully by several

irrigation districts for over 25 years. Improvements and refinements have evolved

during these years. Several types of non-nuclear moisture sensing devices are being

developed and tested. Some of these devices may eventually replace the neutron

moisture gauge. However, this report does not address these latest developments.
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

4

2 - THEORY OF SCHEDULING IRRIGATIONS USING MOISTURE GAUGES

How Irrigation Scheduling Works

The neutron moisture gauge, commonly called a "neutron probe," is a practical tool for

making rapid and accurate measurements of soil moisture. This real time measurement

of soil moisture makes possible quick and accurate determinations of the projected

irrigation dates and the amounts of water to apply and eliminates the need for extensive

computations required to determine crop water use. This field irrigation scheduling

process assumes the plant will use as much water from the soil as possible without

impairing crop production and causing water stress. When the soil moisture content

(SMC) reaches a predetermined minimum allowable moisture content, the crop should

be irrigated. The irrigation scheduling procedures described below refer to the neutron

moisture gauge but are equally applicable to any soil moisture sensing device that can

be calibrated to indicate soil moisture content. 

Gauge readings should be taken biweekly during the summer and weekly during the

winter if crops are grown throughout the year. This provides sufficient information to

determine the rate of moisture depletion in the soil. The readings can be plotted on a

field graph. The amount of water required to refill the soil profile to field capacity can be

accurately determined. The next irrigation date can be predicted as much as a week in

advance. If a computer is available, it can use the gauge readings and compute the

next irrigation date automatically. (The IMS staff at Parker, AZ developed an IBMcompatible computer software package for MS-DOS that makes these computations

and print the reports.)

In graphical irrigation scheduling, the SMC is measured with a neutron moisture gauge

and the measurements are plotted on a graph. The x-axis on the graph represents the

dates readings are taken. The y-axis represents the SMC in each foot of soil in the

profile where a reading is taken. Readings are usually taken from the first-foot, secondfoot, and third-foot increments of the soil profile. In some deep-rooted, permanent

crops, readings may be taken as deep as 5 feet. The readings taken from the first or

top foot of the profile are used to determine the next irrigation date. Combined readings

from the entire profile are used to determine plant water consumption and the amount of

water needed to replenish the root zone. The irrigation efficiency and the leaching

requirement are needed to adjust the irrigation amount. 

Figure 1 shows a typical graph of plotted gauge readings. The minimum allowable SMC

occurring in the first foot of the profile is marked on the graph as a horizontal line. This

is called the refill line or refill point. The refill line is shown as the dashed horizontal line

in Figure 1.

At least two sets of gauge readings must be taken on different days to determine the

next irrigation date. If evapotranspiration rates are changing rapidly, additional readings

will be required. To determine the date, the first-foot SMC readings are plotted
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

5

Figure 1 - Graphical Scheduling with the Neutron Probe
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

6

the graph (see the 0" - 12" Depth portion of Figure 1). A line is drawn through the two

points and extended downward to the horizontal refill line. The date on which the

extended line intersects the refill line is the projected date of the next irrigation. In some

instances, only one reading will be available after an irrigation.

However, the one reading can still be used to predict the next irrigation date, provided

two or more readings were taken before the irrigation and the evapotranspiration rate is

relatively constant. A line having the same slope as the line through the prior readings

can be passed through the single point and extended downward to the refill line. Again,

the date on which the line intersects the refill line is the projected date of the next

irrigation. This prediction will be refined with the next set of readings.

The amount of water used by the crop (includes evaporation) is the total of the

depletions in each foot of the profile. These are shown as A(1), A(2), and A(3) in

Figure 1. The amount to apply is the total of A(1), A(2), and A(3) divided by the

irrigation efficiency.

How Plant Stress is Determined

An essential element in the scheduling process is determining the minimum allowable

SMC. One method for establishing the minimum allowable SMC is to identify the point

at which the plant is no longer adequately watered. A plant's temperature is directly

related to its transpiration rate. Under similar atmospheric conditions, a healthy,

well-watered plant will be cooler than an unhealthy plant. There will be more

evaporative cooling at the leaf surface in the healthy case. It follows then that, by

measuring the plant temperature and comparing it to the air temperature it is possible to

tell if the plant is under stress. Stress would be due to anything that would interfere with

the transpiration process: lack of soil moisture, insect infestations, and other causes. 

However, this discussion assumes that the cause of plant stress is due only to lack of

adequate soil moisture.

Plants that have been stressed require some time to recover after an irrigation. The

length of this recovery period is influenced by several factors. These include the degree

of stress the plant has undergone, the species of the plant, its stage of growth, and its

root depth. The more often the crop must recover from stress, the greater the impact to

crop production and yield. Thus, minimizing or eliminating water stress will improve

crop production and yield. 

Figure 2 illustrates this stress recovery process. A wheat plot received an irrigation on

day 100. This figure shows the changing Crop Water Stress Index (CWSI) during a

portion of the growth period. The CWSI is a measure of water stress ranging from 0.0

shortly after an irrigation to 1.0 at the wilting point.
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

7

Figure 2

CWSI vs. Day of Year for Wheat
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

8

Beginning on day 72, the CWSI increased with time, reaching a value of +0.67 before

irrigation. The CWSI did not drop to zero immediately after the irrigation but decreased

to a minimum on day 106. The 5 to 6 days required to reach the minimum are

necessary to allow the plant to recover from a stressed condition. Time is needed for

the water to move throughout the root zone and rehydrate the leaves. Roots, previously

in dry soil, need time to grow new root hairs to extract soil water at a normal rate. Thus,

too much water stress retards growth and reduces crop production.

Irrigating too frequently has the same impact on crop production and yield as stress. 

Roots are without air after each irrigation until the free water has drained from the soil

profile. During this time, plant growth and development nearly stops.

Research has shown that for any given crop, plant stress can be quantified using three

easily measured parameters. These include the foliage temperature measured with the

infrared thermometer; air temperature; and vapor pressure deficit. The vapor pressure

deficit is commonly called the evaporative demand of the atmosphere. The vapor

pressure deficit is calculated from dry- and wet-bulb air temperatures taken in the field

at approximately the same time as the infrared thermometer readings. Figure 3 is a

graphical representation of the relationship between the crop's foliage-air temperature

differential and the vapor pressure deficit of the atmosphere. The lower bound or

baseline represents the relationship for a healthy, actively transpiring, well-watered

crop. The upper bound is the non-transpiring or wilted crop.

Some terms and definitions about the baselines used in calculating the CWSI are

shown in Table 1. 

 From these baselines one is able to derive the CWSI. If the foliage-air temperature

differential for a given vapor pressure deficit falls on the lower baseline, such as at point

C on Figure 3, the crop is said to be non-stressed or well-watered (transpiring at the

potential rate). If the point is on the upper bound (point A), the crop is at maximum

stress (non-transpiring or wilted). Any point between these limits (point B for instance)

indicates that the plant is under some stress. As point B gets closer to point A, the level

of water stress increases. CWSI is defined as the distance ratio BC/AC.

The CWSI provides a measure of how the crop is responding to existing soil moisture

conditions. A CWSI of near zero (0) indicates the crop is in a well watered condition. 

This well watered condition will continue for as long as the soil moisture can meet the

plant's water needs. A CWSI of one (1) indicates insufficient soil moisture to sustain

plant life. A CWSI value below 0.1 would probably not represent stress but could be a

fluctuation about the baseline. Research has shown that the critical CWSI, where crop

production begins to falter is at 0.3 and 0.45 for wheat and cotton, respectively. Thus, a

small amount of stress is acceptable before irrigation becomes necessary. Research is

continuing to determine the critical CWSI for other crops. Considerable data has been

collected to compute the slopes and intercepts defining the well watered baseline for

several crops.
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

9

Figure 3

Typical Vapor Pressure vs. Temperature Depression Graph

Early in the growing season, infrared measurements may not represent true canopy

temperatures. When there is incomplete canopy cover, the measurement with an

infrared thermometer from a distance of 30 to 45 feet results in an observed surface

temperature that combines both foliage and soil temperatures. The resulting "canopy"

temperature is usually higher than the true foliage temperature. The calculated CWSI is

not a true crop water stress index.

The baseline slope and intercept for any given crop are established by collecting data

while the crop is in a non-stress state. This is usually 4 to 5 days after irrigation. Data

collection should be done at different times of the day. This gives a good spread of data

points due to changes in temperature and humidity. A linear regression on these data

points will give the slope and intercept for the well-watered baseline. An example of

data collected on alfalfa is shown in Figure 4.
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

10

Term

Crop-air temperature differential

 (Tc-Ta)

Definition

Crop canopy temperature as measured with the

infrared thermometer minus the ambient air

temperature (dry-bulb temperature

psychrometer).

Vapor Pressure Deficit (VPD) Potential saturation vapor pressure at the

measured ambient air temperature minus the

calculated existing vapor pressure.

Upper Limit Potential saturation vapor pressure at the

measured ambient air temperature minus the

calculated existing vapor pressure. This is the

canopy-ambient air temperature at which

transpiration has ceased.

Crop Water Stress Index A measure of plant moisture stress which

cannot be greater than one; calculated by

the following formula:

CWSI = B - C

 A - C

where A = upper limit (Tc-Ta)

B = actual measured (Tc-Ta) 

C = value of Tc-Ta if crop

 were well-watered

Table 1

Terms and Definitions

Suggested slopes and intercepts for several crops are shown in Table 2. These may

vary slightly according to region and climate.

Thus, the CWSI can be used to initially set the refill point. Using wheat as an example,

the critical CWSI is about 0.3. Soil moisture reading are taken in the field at the same

time as when the CWSI is determined. When the CWSI reaches approximately 0.3, the

corresponding soil moisture reading in the first-foot interval is noted. This is the

moisture reading that will be plotted as the refill line on the field graph.
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

11

Figure 4

Foliage-air Temperature vs. Air Vapor Pressure Deficit for Well-watered Alfalfa

Grown at a Variety of Specified Sites and Dates During 1980
Chapter 2 - Theory of Scheduling Irrigations Using Moisture Gauges

12

))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))

Common Name Scientific Name Conditions Intercept Slope

)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))

Alfalfa Medicago sativa L. Sunlit 0.51 -1.92

Barley Hordeum vulgare L. Sunlit, Pre-heading 2.01 -2.25

Sunlit, Post-heading 1.72 -1.23

Bean Phaseolus vulgaris L. Sunlit 2.91 -2.35

Shaded -1.57 -2.11

Beet Beta vulgaris L. Sunlit 5.16 -2.30

Chard Beta vulgaris L. Sunlit 2.46 -1.88

Corn Zea mays L. Sunlit, no tassels 3.11 -1.97

Cotton Gossypium hirsutum L. Sunlit 2.00 -2.24

Cowpea Vigna catjang Walp. Sunlit 1.32 -1.84

Cucumber Cucumis sativus L. Sunlit 4.88 -2.52

Shaded -1.28 -2.14

Fig tree Ficus carica L. Sunlit 4.22 -1.77

Guayule Parthenium argentatum Sunlit 1.87 -1.75

Kohlrabi Brassica oleracea

caulorapa communis DC. Sunlit 2.01 -2.17

Lettuce, Leaf Lactuca scariola L. Sunlit 4.18 -2.96

Pea Pism sativam L. Sunlit 2.74 -2.13

Potato Solanum tuberosum L. Sunlit 1.17 -1.83

Pumpkin Cucurbita pepo L. Sunlit 0.95 -1.93

Shaded -1.32 -2.10

Rutabaga Brassica napo-brassica Sunlit 3.75 -2.66

Soybean Glycine max L. Merr. Sunlit 1.44 -1.34

Squash, Curbita pepo L. Sunlit 6.91 -3.09

 Hubbard Shaded 2.12 -2.38

Squash, Zucchini Cucurbita pepo L. Sunlit 2.00 -1.88

Sugar Beet Beta vulgaris L. Sunlit 2.50 -1.92

Sunflower Helianthus annuus L. Sunlit 2.86 -1.96

Tomato, Mill. Lycopersicum esculentum Sunlit 2.86 -1.96

Turnip Brassica rapa L. Sunlit 1.94 -2.26

Wheat, Podura Triticum durum Desf. Sunlit, pre-heading 3.38 -3.25

Shaded, post-heading 2.88 -2.11

Table 2. Well-Watered Base Line Coefficients

for Selected Crops
Chapter 3 - Required Equipment

13

3 - REQUIRED EQUIPMENT

Only a limited amount of equipment is needed to provide irrigation scheduling services

to local farmers. The following section describes the equipment used by the LC Region

and suggests proper usage procedures. 

In addition to normal office space, vehicle, and miscellaneous hand tools, specialized

equipment include:

(1) Neutron moisture gauge

(2) Infrared thermometer

(3) Standardization barrels

(4) 2-inch diameter soil auger (preferably power driven)

(5) Access tubes w/bottom seal and caps (steel or aluminum are preferred)

(6) Access tube driver

The following sections describe the specialized equipment:

The Neutron Measuring Gauge

Description of Gauge

The gauge is the instrument used to measure the moisture in the soil. It is

portable and can be carried from field to field. However, an access tube must be

installed wherever a measurement is to be made.

The gauge uses a high energy source to detect the presence of hydrogen atoms

in the soil. When the high energy source of the gauge is lowered into the access tube,

fast neutrons are emitted. Neutron emission occurs when an alpha particle emitter

(americium) is mixed with beryllium powder in a tightly compressed pellet. Fast

neutrons ricochet strongly from large atoms like a golf ball does when it collides with a

bowling ball. Very little energy is lost. Neutrons are dramatically slowed down,

however, if they collide with hydrogen atoms. Since the hydrogen atoms are the same

mass as the neutron, the neutrons lose energy. The detector tube of the moisture

gauge can then count the slow moving neutrons as they pass through the tube.

In most soils the major source of hydrogen is water; hence, the only major

moderator of fast neutrons would be water. Therefore, when a soil has a high moisture

content (such as at field capacity), the gauge readings would be high. On the other

hand, soils that are dry or are approaching the wilting point would show low readings. 

Thus, a relationship can be established between the gauge counts and the amount of

water in the soil.

Several gauges are on the market now. However, primary experience in the LC

Region has been with the Campbell Pacific Nuclear 503 Moisture Gauge (503 gauge). 
Chapter 3 - Required Equipment

14

 Figure 5

CPN Model 503 Moisture Gauge

If other makes of gauges are in use, consult the owner's manual for a complete

description and operating instructions. 

Two models of the 503 gauge have been used. The Standard 503 gauge (S-503)

displays raw counts that must be converted to the desired units of measure. The Direct

Readout 503 gauge (DR-503) contains a microprocessor that converts raw counts to

any of several desired units of measure.

The primary parts of the 503 gauge are: The

case, the display, and the probe containing the

radioactive source and detector electronics. The

case is a rectangular box approximately 7 inches (18

cm) square by 14 inches (36 cm) length. A tube for

holding the probe is located in the center of the case. 

The readout display is attached to one side. The

lower portion of the case is a neutron shield filled

with a high hydrocarbon paraffin-based wax. The

wax will partially absorb the neutrons emitting from

the source. This also helps shield the user from

stray neutron radiation. Figure 5 is a manufacturer's

photo showing gauge with the probe locked in its

housing. In this configuration, the gauge is ready to

be carried into the field.

The display unit is contained in a 7-inch by 7-

inch by 2-inch box. The display unit contains the

display circuitry, the battery pack, and a liquid crystal

display (LCD) or light emitting diode readout. The

back of the display has a fuse holder and the cable

attachment block.

The probe unit has four main parts: the

external stainless steel case, the radioactive source

permanently secured in the lower part of the probe

tube, the neutron detector tube, and the detector

electronics. The probe, containing the radioactive source and display electronics, is

attached to the display by a cable.

A cable is used to lower the probe tube into the access tube and to transmit

electrical pulses to the display unit. Cable stops are placed on the cable to permit

lowering the probe to predetermined depths in the access tubes. The setting of the

cable stops depends upon the adaptor used to support the gauge on top of the access

tubes. Specifications for the adaptor used in the LC Region are shown in Appendix C. 

With this particular adaptor, the first cable stop should be 26 inches (66 cm) from

the bottom of the detector tube to the base of the first stop. All additional stops are set
Chapter 3 - Required Equipment

15

Figure 6

Taking Moisture readings with the 503.

in increments of 12 inches (30.5 cm) from the base of the first cable stop. The stop

placement should be checked weekly because the insulation on the cable stretches and

slides over time. Heat and rough handling accelerate this process. Changes in stop

placement may cause inconsistent readings.

Use of Gauge

Soil moisture measurements are taken by placing the gauge on top of the access

tube and lowering the probe to the desired depth. Figure 6 shows the gauge positioned

on the access tube to take readings. Readings are taken by pressing START, and

recording the displayed number in the field book. The normal sampling time is 30

seconds for the S-503 and 16 seconds for the DR-503. Therefore, the numbers will not

be displayed immediately after START has been pressed. (Consult the operator's

manual if other intervals are desired.) The S-503 displays raw counts that must be

converted to moisture content using a rating table similar to the tables shown in

Figures 7 and 8. The DR-503 displays the moisture content in several preselected units

of measure. The normal unit of measure used in the United States for agricultural

applications is inches of water per foot of soil depth (in/ft).

The DR-503 can directly display the moisture content and store readings as they

are taken in the field. Some additional steps are needed to initialize the gauge before

taking field measurements. Place the gauge on the shipping case with the probe tube

in the retracted position. Press the key marked UNITS. If the LCD does not display IF

(in/ft), press the STEP key until IF is displayed. When IF is displayed, press the ENTER

key to record desired unit of measure. Now press the key marked TIME. Press the

STEP key until 16 seconds appears. Press the ENTER key to record desired sampling

interval. 

Next take a new standard count. 

Press the key marked STD. The probe

will display the old standard count if one

has been recorded. A new 32-count

standard will be taken automatically

when the START key is pressed. Be

patient, this will take several minutes. 

When the 32-count standard has been

taken, make a note of the new standard

count displayed. Press the STEP key

and this will display the previous

standard count. Press the STEP key

again and the Chi value will be

displayed. The Chi value is the

standard deviation of the 32 counts

divided by the square root of the 32-count average. This value should be 
Chapter 3 - Required Equipment

16

 WATER CONT, IN/FT 06/25/92 PROBE NO 1 (SN=4503)

 ---------------------------------------------------------------

 1000'S HUNDREDS

 0 100 200 300 400 500 600 700 800 900

 ---------------------------------------------------------------

 6| 0.40 0.41 0.42 0.43 0.44 0.46 0.47 0.48 0.49 0.50

 7| 0.51 0.52 0.53 0.54 0.55 0.57 0.58 0.59 0.60 0.61

 8| 0.62 0.63 0.64 0.65 0.67 0.68 0.69 0.70 0.71 0.72

 9| 0.73 0.74 0.75 0.77 0.78 0.79 0.80 0.81 0.82 0.83

 10| 0.84 0.85 0.86 0.88 0.89 0.90 0.91 0.92 0.93 0.94

 11| 0.95 0.96 0.98 0.99 1.00 1.01 1.02 1.03 1.04 1.05

 12| 1.06 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16

 13| 1.17 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27

 14| 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.39

 15| 1.40 1.41 1.42 1.43 1.44 1.45 1.46 1.47 1.48 1.50

 16| 1.51 1.52 1.53 1.54 1.55 1.56 1.57 1.58 1.60 1.61

 17| 1.62 1.63 1.64 1.65 1.66 1.67 1.68 1.70 1.71 1.72

 18| 1.73 1.74 1.75 1.76 1.77 1.78 1.79 1.81 1.82 1.83

 19| 1.84 1.85 1.86 1.87 1.88 1.89 1.91 1.92 1.93 1.94

 20| 1.95 1.96 1.97 1.98 1.99 2.01 2.02 2.03 2.04 2.05

 21| 2.06 2.07 2.08 2.09 2.10 2.12 2.13 2.14 2.15 2.16

 22| 2.17 2.18 2.19 2.20 2.22 2.23 2.24 2.25 2.26 2.27

 23| 2.28 2.29 2.30 2.31 2.33 2.34 2.35 2.36 2.37 2.38

 24| 2.39 2.40 2.41 2.43 2.44 2.45 2.46 2.47 2.48 2.49

 25| 2.50 2.51 2.53 2.54 2.55 2.56 2.57 2.58 2.59 2.60

 26| 2.61 2.62 2.64 2.65 2.66 2.67 2.68 2.69 2.70 2.71

 27| 2.72 2.74 2.75 2.76 2.77 2.78 2.79 2.80 2.81 2.82

 28| 2.84 2.85 2.86 2.87 2.88 2.89 2.90 2.91 2.92 2.93

 29| 2.95 2.96 2.97 2.98 2.99 3.00 3.01 3.02 3.03 3.05

 30| 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.15 3.16

 31| 3.17 3.18 3.19 3.20 3.21 3.22 3.23 3.24 3.26 3.27

 32| 3.28 3.29 3.30 3.31 3.32 3.33 3.34 3.36 3.37 3.38

 33| 3.39 3.40 3.41 3.42 3.43 3.44 3.46 3.47 3.48 3.49

 34| 3.50 3.51 3.52 3.53 3.54 3.55 3.57 3.58 3.59 3.60

 35| 3.61 3.62 3.63 3.64 3.65 3.67 3.68 3.69 3.70 3.71

 36| 3.72 3.73 3.74 3.75 3.76 3.78 3.79 3.80 3.81 3.82

 37| 3.83 3.84 3.85 3.86 3.88 3.89 3.90 3.91 3.92 3.93

 38| 3.94 3.95 3.96 3.98 3.99 4.00 4.01 4.02 4.03 4.04

 39| 4.05 4.06 4.07 4.09 4.10 4.11 4.12 4.13 4.14 4.15

 40| 4.16 4.17 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26

 41| 4.27 4.29 4.30 4.31 4.32 4.33 4.34 4.35 4.36 4.37

 42| 4.38 4.40 4.41 4.42 4.43 4.44 4.45 4.46 4.47 4.48

 43| 4.50 4.51 4.52 4.53 4.54 4.55 4.56 4.57 4.58 4.60

 44| 4.61 4.62 4.63 4.64 4.65 4.66 4.67 4.68 4.69 4.71

 45| 4.72 4.73 4.74 4.75 4.76 4.77 4.78 4.79 4.81 4.82

 46| 4.83 4.84 4.85 4.86 4.87 4.88 4.89 4.91 4.92 4.93

 47| 4.94 4.95 4.96 4.97 4.98 4.99 5.00 5.02 5.03 5.04

 48| 5.05 5.06 5.07 5.08 5.09 5.10 5.12 5.13 5.14 5.15

 49| 5.16 5.17 5.18 5.19 5.20 5.22 5.23 5.24 5.25 5.26

 50| 5.27 5.28 5.29 5.30 5.31 5.33 5.34 5.35 5.36 5.37

 COUNT INTERVAL = 0.001 IN/FT PER 10 COUNTS

 EQUATION: W=0.0001107 x C -.264

Figure 7

Probe Rating Table - Uniform Count Increment
Chapter 3 - Required Equipment

17

COUNT INCHES

 3037 = .50

 3227 = .55

 3417 = .60

 3606 = .65

 3796 = .70

 3986 = .75

 4176 = .80

 4366 = .85

 4555 = .90

 4745 = .95

 4935 = 1.00

 5125 = 1.05

 5315 = 1.10

 5505 = 1.15

 5694 = 1.20

 5884 = 1.25

 6074 = 1.30

 6264 = 1.35

 6454 = 1.40

 6643 = 1.45

 7023 = 1.55

 7213 = 1.60

 7403 = 1.65

 7592 = 1.70

 7782 = 1.75

 7972 = 1.80

 8162 = 1.85

 8352 = 1.90

 8541 = 1.95

 8731 = 2.00

 8921 = 2.05

 9111 = 2.10

 9301 = 2.15

 9491 = 2.20

 9680 = 2.25

 9870 = 2.30

10060 = 2.35

10250 = 2.40

10440 = 2.45

10629 = 2.50

COUNT INCHES

10819 = 2.55

11009 = 2.60

11199 = 2.65

11389 = 2.70

11578 = 2.75

11768 = 2.80

11958 = 2.85

12148 = 2.90

12338 = 2.95

12528 = 3.00

12717 = 3.05

12907 = 3.10

13097 = 3.15

13287 = 3.20

13477 = 3.25

13666 = 3.30

13856 = 3.35

14046 = 3.40

14236 = 3.45

14615 = 3.55

14805 = 3.60

14995 = 3.65

15185 = 3.70

15375 = 3.75

15564 = 3.80

15754 = 3.85

15944 = 3.90

16134 = 3.95

16324 = 4.00

16514 = 4.05

16703 = 4.10

16893 = 4.15

17083 = 4.20

17273 = 4.25

17463 = 4.30

17652 = 4.35

17842 = 4.40

18032 = 4.45

18222 = 4.50

18412 = 4.55

COUNT INCHES

18601 = 4.60

18791 = 4.65

18981 = 4.70

19171 = 4.75

19361 = 4.80

19551 = 4.85

19740 = 4.90

19930 = 4.95

20120 = 5.00

20310 = 5.05

20500 = 5.10

20689 = 5.15

20879 = 5.20

21069 = 2.25

21259 = 5.30

21449 = 5.35

21638 = 5.40

21828 = 5.45

22208 = 5.55

22398 = 5.60

22588 = 5.65

22777 = 5.70

22967 = 5.75

23157 = 5.80

23347 = 5.85

23537 = 5.90

23726 = 5.95

23916 = 6.00

24106 = 6.05

24296 = 6.10

24486 = 6.15

24675 = 6.20

24865 = 6.25

25055 = 6.30

25245 = 6.35

25435 = 6.40

25624 = 6.45

25814 = 6.50

Figure 8. Probe Rating Table

Uniform Moisture Content Increment
Chapter 3 - Required Equipment

18

between 0.75 and 1.25. If the Chi value is within these limits, press the ENTER key and

the new standard count will be entered into the probe. If the Chi value is out of range,

press the CLEAR key, and initiate the standard count procedure again. If the Chi value

is still out of range after the third try, the probe will require servicing.

If site locations and readings are to be stored in the gauge's memory, the memory

area must be formatted. To do this, press the FMT key. The gauge will display K Data

1. Key in a 1 if the gauge does not display a 1. Press the ENTER key. The gauge will

display Depths. The gauge can record up to 15 depths but measurements are normally

taken at three depths per tube site. However, the gauge will expect the same number

of depths at each site. When the number of depths is keyed in, press the ENTER key. 

The gauge will store the number of depths to be read and will display Set FMT?. Press

the ENTER key and the gauge should display Ready. To clear all stored gauge

readings, press the FMT key; then press ENTER until Ready appears in the display.

The following procedure should be used when storing readings in the DR-503

memory. Place the gauge on the access tube. Press LOG, key in the farm number,

and press ENTER. Key in the field number and press ENTER. M3 will be displayed. 

Lower the probe to the first cable stop and press START. In about 16 seconds the

measurement is displayed. Press ENTER to store the measurement if the

measurement appears correct. Otherwise, press START and repeat the reading. M2

will then be displayed after the gauge has stored the reading. Lower the probe to the

next stops repeating the START and ENTER sequence at each stop. Three readings

must be recorded for each site. If readings are to be taken at only two depths, key in 0,

and press ENTER in place of the third reading. After the third reading has been

entered, the total moisture will be displayed. Press ENTER if correct. The gauge will

then display IS DATA OK?. Press ENTER to store all data for the site. The gauge is

now ready to take readings at the next site.

The above procedures assume that the gauge has been properly

standardized. (See "Standardizing Gauge.")

Standardization Barrels

Standardization barrels are used to verify correct calibration of each gauge and to

insure that all gauges are calibrated to the same standard. Some gauges change

calibration gradually from season to season, especially in hot climates. The set of

standardization barrels consists of two, large 30- or 55-gallon barrels. One is filled with

air-dried sand and the other with saturated sand. The air-dry sand approximates the

lower limit of the moisture contents encountered in the field and the saturated sand

approximates the upper limit. Local soils with high silt and clay contents may be used in

place of saturated sand. These soils should be near field-capacity when used.

Both barrels are fitted with access tubes centered in the barrels. The access

tubes should be of the same material as the access tubes used in the field. Each tube

extends far enough above the top of the barrel so the probe detector tube will be
Chapter 3 - Required Equipment

19

Figure 9

Gauge On Standardization Barrel

Figure 10

Infrared Thermometer

suspended in the center of barrel when hanging on the second cable stop. Figure 9

shows a moisture gauge set up on a standardization barrel ready to take a

measurement.

Be careful when placing sand in the barrels so

that the sand is adequately compacted to eliminate

future settling. The barrels should be filled with

sand to within 1-inch of the top. Water is added to

the sand in one barrel until the sand is saturated

and water stands freely above the sand. A lid with

a 2-3/16-inch diameter hole to accommodate the

access tube is placed on the top of each barrel. 

The lid should be sealed on the dry barrel with

silicone or rubber adhesive sealant as soon as the

sand has been compacted. The lid is not sealed on

the wet barrel. An inspection hole could be

provided to facilitate maintaining the water at a

constant level above the sand. Otherwise, provide

an external filling tube as shown in Figure 9.

The apparent moisture content of each barrel

is measured with a gauge accurately calibrated to

local soil conditions. Twenty moisture

measurements are taken and averaged to

determine the apparent moisture content of each

barrel. Outside influences can affect gauge

readings, especially the dry barrel readings. This

can be minimized by maintaining the barrels and

surrounding area in a constant configuration.

Alternately, sand samples can be taken from

each barrel. The samples should be analyzed in

the laboratory to determine actual moisture content

of each barrel.

Infrared Thermometer

Description of Thermometer

Soil water content can be inferred from tensiometers or

measured with the neutron moisture gauge, but just knowing

how much water is in the soil is not enough. One must also

know the minimum amount of water that must remain in the soil

without reducing crop production. The infrared thermometer

(Figure 10) provides a means of determining the degree of crop

water stress by measuring crop foliage temperature. The
Chapter 3 - Required Equipment

20

Figure 11

Measuring canopy temperature

with an infrared thermometer.

complete infrared thermometer includes a Bendix psychrometer for measuring wet and

dry-bulb temperatures. The kit also contains a reference temperature black body for

calibrating the infrared thermometer. Newer models of the infrared thermometers have

the necessary built-in sensors and microprocessor to determine the CWSI directly.

Use of Thermometer

Crop foliage temperatures (and associated relative humidity) are measured to

develop the well-watered baseline curves and to determine plant water stress

conditions. The infrared thermometer measures the temperature of the crop foliage,

while the Bendix psychrometer measures wet-bulb and dry-bulb temperatures needed

to determine relative humidity.

Data for the well-watered baseline may be collected anytime from about 9 a.m. to

3 p.m. When using the infrared thermometer for detecting stress, readings are

preferably taken between noon and 2 p.m., when the sun is usually higher overhead. 

During these hours, shadows are the smallest and transpiration is at its peak. It is more

effective to read each field at approximately the same time each day when checking for

stress.

The temperature readings should all be taken

in an area of the field where the largest percentage

of the whole field will be represented. Readings

should be taken approximately 50 feet into the field

so temperatures will not be influenced by the edge

effect of the field. Edges of the field may not

receive as much water or may be dried out faster by

winds. Taking temperatures from eight directions is

necessary to give a good average of the canopy or

foliage temperature. Figure 11 illustrates the

procedure for measuring canopy temperatures with

an infrared thermometer.

The wet-bulb and dry-bulb temperatures

should be taken as soon as possible after taking the infrared thermometer readings. 

First, apply distilled water to the sock of the wet-bulb. Be careful not to get water in the

fan mechanism. Shake off the excess, then turn on the fan. Hold the psychrometer

approximately 1 meter from the ground and upwind from body temperature influences. 

The wet-bulb reaches its lowest temperature in 1 minute or less. Read both the wetand dry-bulb temperatures together. Newer versions of the infrared thermometer

compute and display the vapor pressure deficit and the crop temperature differential

directly. In this case, a psychrometer is not necessary to determine wet-bulb and drybulb temperatures.

Data collected at any given site should be recorded on a form similar to the one in

Figure 12. The top half of this form contains information regarding the site and data
Chapter 3 - Required Equipment

21

quality. Data quality refers to the existing climatic conditions when the data is taken and

should either be a 1, 2, or 3. If sunny, with light winds, data quality is 1 for GOOD. If

slight overcast or just windy, data quality is 2 for FAIR. If cloudy or high winds, readings

probably should not be taken, but the data quality is 3 for POOR. Be sure to enter the

crop name to the top right of TEMPERATURE MEASUREMENTS. Under the heading

TEMPERATURE MEASUREMENTS, fill in the time of the readings and the field

number or other reference to the area where readings are taken. Then record the drybulb, wet-bulb, and eight infrared thermometer readings.

Periodic checks should be made with the infrared thermometer against a

calibration source or black body to see that it is reading correctly. Normally, the Bendix

psychrometer need only be watched for loss of power due to low batteries. Fluctuating

fan speeds, due to low batteries, cause the wet-bulb temperature to descend slowly and

result in inaccurate or variable readings.

Soil Auger

A 2-inch diameter soil auger is needed to bore holes to permit the installation of

access tubes. Any type of auger capable of boring a 2-inch diameter hole deep enough

to accept the longest access tube in use is acceptable. However, a power-driven,

continuous-flite auger is preferred. The power-driven auger drills holes much faster and

speeds installation of access tubes. However, extra care must be taken to ensure that

the auger does not over-bore the hole diameter.

Access Tubes

Probe access tubes must be installed at each location where soil moisture

measurements will be taken. These tubes may be steel, aluminum, or PVC pipe for the

nuclear gauge. Steel tubes are preferred because of better durability and lower cost.

The steel access tubes are 2-inch (50 cm) inside diameter, thin walled, rigid steel

conduit. The conduit is purchased in 10-foot sections and then cut to the desired

length. The tube is sealed on the bottom with a 1f-inch chain link fence post cap and

water repellent adhesive. The top is covered with a removable cap to protect the tube

and to keep out irrigation water and debris. The cap consists of a 21⁄2- by 21⁄2- by 1⁄4-inch

steel plate bolted on top of a No. 11 rubber stopper. The cap should be painted with a

highly visible color of paint for ease in locating the tube. If a tube cannot be located in

a field, the steel plate on the cap helps a good metal detector locate the tube. Figure 13

shows a typical cap assembly.
Chapter 3 - Required Equipment

22

PLANT FOLIAGE TEMPERATURE DATA SHEET

 LOCATION Double Bar Ranch 

 YEAR DAY - DATE 4/22/95 BY LM DATA QUALITY 1 

 INSTRUMENT

 MODEL No. - SERIAL No. - 

 CALIBRATION CHECK:

 TIME INST. REF.

 1400 24.6 24.6 

 

 WEATHER

 CLOUD CLOUD WIND WIND

 SUN X HAZE - TYPE - COVER - SPEED 4 DIRECTION SE

 PRECIP. IRRIGATION Field S10 4/18 

 COMMENTS: Plants are in the milky dough stage 

 

 

 TEMPERATURE MEASUREMENTS CROP 

SITE TIME FLD

DRY

BULB

WET

BULB

DIRECTION OF VIEW

N NE E SE S SW W NW

1 1410 S10 24.7 15.0 23.5 23.7 23.7 23.4 23.6 23.2 23.2 22.8

2

3

4

5

6

7

Figure 12

Sample Plant Foliage Temperature Data
Chapter 3 - Required Equipment

23

Figure 13. Access Tube Cap Assembly

Figure 14. 

Access Tube Driver

The length of the access tube is

determined by the root structure of the

crop being scheduled. For most field

crops, a 44-inch (112 cm) tube will be

long enough. It will permit readings down

to 3 feet and provide extra clearance

below the probe. This tube length is

adequate for crops like cereal grains,

alfalfa, cotton, and most vegetables.

A longer tube is preferred for citrus,

grapes, dates, and other tree crops. 

Also, the longer tube will allow early

identification of water table problems.

Tube installation requires drilling a 2-inch diameter hose several inches deeper

that the tube length. The extra depth accommodates some soil sloughing that usually

occurs when the tube is driven into the hole.

Access Tube Driver

A specially designed driver is used to install steel access

tubes in holes that have been previously bored in the ground. 

The driver consists of a drop-hammer, guide rod, and anvil. 

The anvil is specifically designed to protect the top of the tube

and prevent tube deformation during the driving process. The

guide rod is attached to the anvil to center the force of the

drop-hammer. 

In operation, the driver works much like a steel fencepost driver. The anvil is inserted in the top of the tube. The

drop-hammer is repeatedly raised to the top of the guide rod

and released. The force of the falling drop-hammer drives the

tube into the ground. Figure 14 shows a photograph of an

access tube driver.

PVC access tubes do not require a specially designed

driver. A hard rubber mallet is adequate for driving these

access tubes.
Chapter 4 - Getting Started

24

4 - GETTING STARTED

The LC Region started its field irrigation scheduling services on a demonstration basis

at the two previously mentioned irrigation districts and on the Native American Indian

Reservation. The initial staff provided at each site consisted of a hydraulic engineer and

a soil scientist provided by Reclamation and a soil scientist or soil conservationist

provided by the partner. The partners provided office space for each team. 

Reclamation provided furniture, equipment, and supplies. Reclamation and the partners

provided vehicles for their own employees. As the programs expanded beyond the

initial acreage enrollment, the partners provided additional field technicians. The

ultimate intent was to withdraw Reclamation employees after 3 to 5 years when the

partners could sustain the programs on their own. Lessons learned and insight gained

by Reclamation through these demonstration activities have resulted in the following

suggestions for starting a new field irrigation scheduling service.

Starting a New Field Irrigation Scheduling Service

Starting a new field irrigation scheduling service involves several activities. These

include recruiting field technicians; obtaining office space, equipment, and vehicles;

preparing the equipment; and enrolling participating farmers.

Local procedures will govern the recruiting of field technicians. However, the

technicians should have some knowledge of irrigated agriculture. They also should

have the skills to use the specialized equipment used for irrigation scheduling. Finally,

they should be able to communicate effectively with the farmers. 

Similarly, local conditions will govern the availability of office and work space. The

neutron moisture gauge will require special provisions for licensing, storage, and

transportation. The technicians also must be trained and certified by a qualified

Radiation Safety Officer.

Local policies will determine how participating farmers will be recruited and enrolled. 

Enrollment should be open to all local farmers. However, program success is the

greatest when first consideration is given to the most progressive and cooperative

farmers. Experience has also demonstrated that the program is the most successful

when all of a participating farmer's fields are receiving scheduling services. Farmers

cannot assess the benefits of the service fully when just a few "demonstration" fields are

receiving the service. The farmer must still schedule the irrigations on the non-enrolled

fields. The demonstration fields are just considered a curiosity.

Compliance with regulations governing the possession and use of neutron moisture

gauges is essential. The use of these gauges is regulated by Federal or State agencies

because the devices contain radioactive sources. Federal agencies usually are under

the jurisdiction of the Nuclear Regulatory Commission (NRC). Irrigation districts and

private owners are under the jurisdiction of the State regulatory agency. 
Chapter 4 - Getting Started

25

The owner must first obtain a license from the NRC and/or appropriate State agency

before purchasing and taking delivery of nuclear moisture gauges. To get a license, the

owner must meet conditions for storage and use of the nuclear gauge as set by either a

state or federal regulatory agency. The owner should consult with the appropriate

regulatory agency for specific requirements. Typically, the storage area must be a

specified distance away from areas frequented by people and animals. It must always

be locked and must be properly marked. Again, all operators must be trained and

certified by a certified training instructor. Each person operating or servicing the gauges

must be supplied with a dosimeter film badge to monitor radiation exposure. These

badges must be replaced and analyzed periodically. Finally, a record keeping system

must be set up to maintain film badge and leak test reports and other correspondence. 

The NRC and/or State agency will periodically inspect the site to insure that the owners

and operators are in compliance with the regulations. The inspection includes an

examination of the record keeping system. Finally, Department of Transportation

guidelines must be observed when the nuclear gauge is transported.

The remainder of the discussion on getting the service started concentrates on setting

up the equipment and compiling the necessary information needed to operate the

service.

Calibrating Gauge 

The neutron moisture gauges must be initially calibrated so the readings (counts)

can be related to actual soil moisture. Soils have different chemical and physical

properties that may affect the gauge readings. Calibration curves should be developed

for local conditions. The gauge, thus calibrated, can be used to measure the equivalent

moisture content of the standardization barrels.

To calibrate the gauge, select representative sites of the soils in the area to be

monitored. As the access tube hole is being bored, take soil samples at different

depths. Use a soil sampler capable of taking a sample of a known volume. Seal the

samples in cans for later moisture determination in the laboratory. After installing the

access tube, take gauge readings at the same depths where the samples were taken

and record the measurements. Enough sites should be selected to give readings for a

range of different moisture levels (wet, moist, and dry). The soil samples taken during

access tube installation are analyzed in the laboratory to determine the amount of

moisture contained in the different soils. 

A graph is prepared with the gauge readings on one axis. The moisture content of

the soil, as determined in the laboratory, is on the other. The curves are then

developed and plotted on a graph similar to Figure 15. A straight line is then fitted to

the plotted points and the coefficients of the line are determined. A graph or table is

then prepared which relates the amount of moisture in the soil to a given gauge reading. 

This table also can be developed on the computer. The coefficients of the line also may

be entered into the gauge if the gauge is capable of displaying readings in actual

moisture content.
Chapter 4 - Getting Started

26

Some people contend that a calibration curve must be developed for each soil

type to be monitored. This is true if detailed research is involved. However, for the

practical use of the gauge for predicting and scheduling irrigations, experience shows

that one calibration curve is normally sufficient. There may be some instances when

two curves are necessary, due to an extreme difference in local soil types.

Standardizing the Neutron Moisture Gauge

Ideally, the calibration procedure described above should be repeated each time a

new gauge is put in service. The process also should be repeated at frequent intervals

to insure continued accurate operation of each gauge. Unfortunately, the process is

very time consuming.

An alternate procedure involves the use of standardization barrels. These barrels

were previously described in the "Required Equipment" chapter. The barrels with

known moisture content simulate typical "wet" and "dry" conditions in the field. 

Calibration curves are developed using gauge readings from the two barrels. This

replaces the process of taking readings in the field and determining the soil moisture in

the laboratory.

Standardization procedures are somewhat different for the S-503 and the DR-503

gauges. Coefficients for the calibration curve must be computed manually for the S503. Coefficients are computed automatically by the DR-503.

To standardize the S-503, take sets of 20 measurements with the probe lowered

to the center each the barrel. For each set, the readings (counts) are recorded in a

notebook, totaled, and averaged. The standard deviation is also computed.

The calibration equation is of the form: M=aC+b

where: M= Moisture content in inches of water per foot of soil depth

C= Counts shown on display

a= Slope coefficient

b= Intercept coefficient

and: a= (Mw - MD) and b= Mw - aCw

 (Cw - CD)

where: Mw= Moisture content of wet barrel (in/ft)

Cw= Average for 20 readings on wet barrels (counts)

MD= Moisture Content of Dry barrel (in/ft)

CD= Average for 20 readings on Dry barrel (counts).
Chapter 4 - Getting Started

27

Figure 15. Soil Moisture in Inches per Foot of Depth vs.

Count Ratio of the Neutron Moisture Gauge

Coefficients "a" and "b" are used in the calibration equation to develop rating

tables used by field personnel to convert displayed counts to equivalent moisture
Chapter 4 - Getting Started

28

contents. Samples of two typical rating tables were previously shown in Figures 7 and

8.

Data recorded during the standardization process also can be used to verify

proper operation of the gauge. No more than 6 of the 20 readings should be outside the

acceptable range. The acceptable range is plus or minus the square root of the

average count above and below the average count. The Chi value obtained by dividing

the square root of the average count by the standard deviation should be between 0.75

and 1.25 (see Figure 16). If either of the above tests fail, additional sets of 20 readings

should be taken on the appropriate barrel. Several additional failures indicate the

gauge is defective and should be repaired.

To standardize the DR-503, place the gauge on the wet barrel and lower the

probe to the center of the barrel. Press the key marked CALIB and the gauge will

display Cal 1 IF. This is the first of eight calibrations that can be stored in the gauge. 

Only one calibration is needed for most agricultural soils. Now press the ENTER key. 

The gauge will display COEFFS?. Press the STEP key until SLFCAL is displayed. 

Press the ENTER key. The gauge will display M2 0.0--- and will wait for entry of the

moisture equivalent of the wet barrel (inches of moisture per foot of soil). Key in wet

barrel moisture content and press the ENTER key. The gauge will display C 2 0---. (It

is waiting for entry of the average count for the wet barrel.) Press the START key and

the gauge will determine the average count for the wet barrel. The gauge will take

about 4 minutes to complete the measurement. When the measurements are

completed, press the ENTER key. Place the gauge on the dry barrel. If the gauge is

now displaying M1 0.00, it is waiting for the moisture equivalent of the dry barrel to be

keyed in. Key in this number and press the ENTER key. The gauge will display C1 0---

and wait for the average count of the dry barrel to be keyed in. By pressing the START

key, the gauge will determine the average counts in about 4 minutes. When the gauge

is finished counting, press the ENTER key. The LCD will flash the word COMPUTE on

the display screen and then will show READY. Calibration is complete.

Correct operation can be verified by taking a measurement on one of the barrels. 

Lower the probe to the center of the barrel and press START. The displayed reading

should be within ±0.05 in/ft of the barrel's equivalent moisture content. If the test fails

for repeated measurements, repeat the standardization process and try the test again. 

The previously described tests for the S-503 should be used if the gauge still cannot

measure the equivalent moisture content within ±0.05 in/ft.

As shown above, the barrels provide a quick means of verifying proper gauge

operation. Simply measure the moisture content of one or both barrels before taking

the gauge into the field each day. All gauges should be more extensively checked out

on the barrels to identify changes caused by electrical breakdown or drift at least

weekly. Standardization procedures should be followed any time drift is apparent.
Chapter 4 - Getting Started

29

NEUTRON PROBE

STANDARD COUNT DETERMINATION

Probe No. H32074503

DATE: 6-10-85 OPERATOR: LM

Reading No. Count Rates

 1. 29248

 2. 29543

 3. 29416

 4. 29386

 5. 29280

 6. 29725 High

 7. 29245

 8. 29133 Low

 9. 29603 High

10. 29330

11. 29100 Low

12. 29391

13. 29382

14. 29648 High

15. 29401

16. 29422

17. 29370

18. 29417

19. 29190 Low

20. 29339

 Total = 587629 ___

 Average = 29381 oAvg = 171.4 ___

 Average + oAvg = 29552

 ___ {Acceptable Range

 Average - oAvg = 29210

 STD DEV = 161.6

 ___

 Chi or RATIO = oAvg / STD DEV = 1.06

 (Acceptable range = 0.75 - 1.25)

REMARKS: Probe is demonstrating good performance.

Figure 16

Neutron Probe Standard Count Determination
Chapter 4 - Getting Started

30

Establishing Well-Watered Baseline

The well-watered baseline has been established for many common crops. 

Baseline coefficients for these crops have been shown previously in Table 2. 

Unfortunately, a desired crop may not be included in the table. In this event, a new

baseline must be developed.

The data needed to develop the new baseline for a crop must be collected in the

field. Infrared thermometer and Bendix psychrometer temperature measurements

should be taken from as many recently irrigated fields as practical. Several readings 

should be made between 9 a.m. and 3 p.m. in each field to sample a range of

temperature and humidity conditions.

Analysis of the data requires computing the temperature depression (Tc-Ta) and

the vapor pressure deficit (VPD) for each set of measurements (see [B] and [C] in the

hand calculation example to follow). New versions of the infrared thermometer display

these measurements directly. A graph similar to Figure 4 is next prepared. Plot the

VPD and (Tc-Ta) values for each set of measurements. The coefficients of the wellwatered baseline are then determined using a standard linear regression process. The

coefficients can now be used for making future CWSI computations.
Chapter 5 - Scheduling Irrigations

31

5 - SCHEDULING IRRIGATIONS

Starting Irrigation Service to a New Field

Once a field has been enrolled to receive irrigation scheduling services, several

preliminary activities are required before active scheduling can begin. This discussion

assumes that the necessary equipment and technicians are available to provide the

scheduling service. Preliminary activities include selecting a site for the access tube,

installing an access tube, and determining the "refill and full points."

Locating Access Tube Site

Selecting the proper site for tube installation requires analysis of several factors

including (1) accessibility to the tube, (2) method of irrigation, (3) soil type, and (4) crop

stand and crop cover.

Accessibility. The tube should be located where it is readily accessible

from normally traveled roadways. If possible, tubes should be located away from areas

that may cause frequent hindrances to vehicle or foot travel. Tube accessibility will

have a bearing on the number of sites that can be read in a day by a technician.

Irrigation Method. With any type of flood irrigation system, the tube should

be located in the third quarter of the field below the head ditch. The first and second

quarters may be over irrigated and should be avoided. The fourth quarter of the field,

furthest from the head ditch, may receive insufficient water or may have excess water

ponded. Tube location is not critical with drip or sprinkler irrigation systems except that

tubes should not be placed directly under a sprinkler head or adjacent to an emitter. 

Theoretically, all parts of the field receive the same amount of water from these

systems. The extreme edges, high or low spots, or obvious dry spots in the field should

be avoided.

Soil Types. The access tube should be located in the area containing the

predominate or representative soil in the field to achieve most uniform results. 

Extremely sandy or clay soils should be avoided, if possible. Adjustments can be made

in the refill point to accommodate these soil types if they represent significant portions of

the field.

Crop Stand. The tubes should be located where crop stands are uniform

and healthy. Stunted, bare, or weedy areas should be avoided. These areas do not

represent normal consumptive use or soil conditions.
Chapter 5 - Scheduling Irrigations

32

Installing Access Tubes

The installation of access tubes is a simple procedure, if the proper equipment is

available and good work methods are employed. A 2-inch hole is bored several inches

deeper than the length of the tube to be installed. The extra depth collects any soil that

might slough off the sides of the hole as the tube is driven into the ground. A hand

auger is adequate but a power auger is preferred for boring the hole. Be careful to

avoid over-sizing the hole diameter when using the power auger. There should be no

air spaces around the tube. Loose soil deposited around the mouth of the hole should

be carefully cleaned away from the hole before inserting the tube. 

The tube is inserted into the hole, sealed end first. It is pushed down by hand and

driven in flush with the ground surface using the tube driver. In some installations,

tubes are not susceptible to equipment damage and do not need to be installed flush

with the ground. However, uniformly installing all tubes flush with the ground surface

will insure that all measurements are taken at consistent depths. Any loose soil around

the top of the tube can be compacted. A brightly painted cap should be placed on the

tube as soon as the installation is complete.

The tube location can be marked with a stake and flagging for easy location by the

technician. In some situations the stake would disrupt cultural operations (like cutting

alfalfa). In this case, the stake should be placed at the edge of the field. It should be

marked with the number of paces between the stake and the tube.

Determining Refill Point

The refill point, or minimum allowable SMC at the time of irrigation, is established

in the top foot of the soil profile using one or a combination of three criteria: (1) at what

depletion should irrigation result in optimum yields; (2) at what depletion would the crop

show water stress; and (3) how dry would the farmer allow the soil to become before

irrigating.

Using Optimum Moisture Content. Most crops can tolerate some stress

before yields are affected. The moisture content at which irrigation should result in

optimum yield, can be identified by measuring the water content using the gauge and

the soil moisture tension using a tensiometer. Research has identified an optimum

moisture tension for many crops. Irrigating before reaching the optimum tension can

waste water and retard plant growth. Delaying irrigations beyond the optimum tension

reduces crop yield. The refill point is the moisture content that occurs at the optimum

soil moisture tension. Unfortunately, the tensiometer has been unsatisfactory for largescale irrigation scheduling activities. It has limited reliability and requires too much

labor to keep the tensiometer operating properly. The accuracy of this method depends

upon the reliability of the tensiometers and how closely local conditions duplicate

conditions where optimum tensions were determined.
Chapter 5 - Scheduling Irrigations

33

Using Crop Water Stress Index (CWSI). The infrared thermometer is

showing promise in identifying the optimum moisture content. The CWSI, determined

with the infrared thermometer, is compared to the SMC measured with the gauge. The

refill point is the moisture content that is measured when the optimum CWSI occurs. As

previously mentioned, the optimum CWSI for cotton and wheat are 0.45 and 0.3,

respectively. Research is continuing to determine the optimum CWSI for other crops. 

This optimum value may vary depending upon the stage of growth. This is the most

accurate method for determining the refill point.

The CWSI is computed using data collected with infrared thermometer and

Bendix psychrometer. The computations can be made using a computer or by hand. 

Newer versions of the infrared thermometer display the CWSI directly.

The computer program VEGY, developed by the Bureau of Reclamation,

Yuma Area Office, can be used to make the computations. (Instructions for using

VEGY along with a program listing can be found in Appendix E.) Field readings from

the Plant Foliage Temperature Data Sheet (see Figure 12) are entered into Program

VEGY to compute the CWSI. Final output for two fields, S10 and 9, is shown in

Figure 15. Note that field S10 is still well-watered with a CWSI of only 0.02. Field 9 is

considered in a stress state with a CWSI of 0.45. Remember, CWSI ranges from 0.0 to

1.0.

Hand calculating the CWSI is a rather lengthy procedure, where errors are

easily made. The field data used in the calculations are shown in Figure 18. Other

values required in the computation are determined from Appendixes A and B. The

procedure is illustrated in Figure 19 to show how the CWSI is derived.

Using Observation of Visible Stress. The soil moisture depletion at which

the crop shows water stress can also be used to establish the refill point. The refill point

would be the moisture content measured at the time stress is first noted. Salt or similar

influences are accommodated by minor upward adjustments of the refill point until such

stress is not observable. Setting the refill point by this method is not as accurate as

previously discussed methods. However, it will produce acceptable results that can

improve irrigation efficiency and crop yields.

Using Farmer's Judgement. Finally, the farmer's judgement and

experience can be used to set the refill point. The refill point would be the moisture

content measured just before the beginning of a normal irrigation. This is usually the

least accurate method for determining refill points.

The refill points established using observed stress or the farmer's judgement

are the easiest to obtain and often the most agreeable to the farmer. The other

methods can be used to refine these refill points. These refinements may have to be

made gradually over a period of several irrigations to be acceptable to the farmer.
Chapter 5 - Scheduling Irrigations

34

CROP WATER STRESS INDEX COMPUTATIONS

11/15/90

Page 1 

 SAMPLE SAMPLE

 DATE TIME CROP FIELD

 4/22/95 1410 WHEAT S10 

 DRY BULB WET BULB SAMPLE TEMPERATURES DATA

 TEMP TEMP (1) (2) (3) (4) (5) (6) (7) (8) WIND QUALITY

 24.7 15.0 23.5 23.7 23.7 23.4 23.6 23.2 23.2 22.8 4 SE GOOD

 SLOPE: -3.25

 OFFSET: 3.38

 TC-TA -1.31 C

 VAPOR PRESSURE DEFICIT: 2.04 KPA

 UPPER LIMIT: 5.61 C

 CROP WATER STRESS INDEX: 0.22

 RELATIVE HUMIDITY: 34.28%

 - - - - - - - - - -

 SAMPLE SAMPLE

 DATE TIME CROP FIELD

 4/22/95 1410 WHEAT 9 

 DRY BULB WET BULB SAMPLE TEMPERATURES DATA

 TEMP TEMP (1) (2) (3) (4) (5) (6) (7) (8) WIND QUALITY

 27.7 14.2 28.9 29.0 28.4 26.4 27.5 27.5 27.2 27.3 10 N GOOD

 SLOPE: -3.25

 OFFSET: 3.38

 TC-TA .07 C

 VAPOR PRESSURE DEFICIT: 2.98 KPA

 UPPER LIMIT: 4.30 C

 CROP WATER STRESS INDEX: 0.45

 RELATIVE HUMIDITY: 19.73%

Figure 17

Sample Printout from Program VEGY

Establishing Full Point

Both the refill and full points must be identified to establish the soil moisture

holding capacity of any field. The full point, an approximation of field capacity, is the

amount of moisture in the soil after initial drainage has removed the excess water. It is

the total of the moisture contents in each foot of soil profile. This measurement is taken

1 or 2 days after the irrigation. The technician must be able to walk on the field without

sinking into the soil or causing damage to the crop.
Chapter 5 - Scheduling Irrigations

35

CROP WATER STRESS INDEX COMPUTATIONS

11/15/90

Page 1 

 SAMPLE SAMPLE

 DATE TIME CROP FIELD

 ------ ------ ---- -----

 7/25/95 1215 COTTON S10 

 DRY BULB WET BULB SAMPLE TEMPERATURES DATA

 TEMP TEMP (1) (2) (3) (4) (5) (6) (7) (8) WIND QUALITY

 -------- -------- ---- ---- ---- ---- ---- ---- ---- ---- ---- -------

 37.0 20.0 30.0 31.7 32.1 32.3 32.2 32.3 32.8 32.1 5 SSE GOOD

 SLOPE: -2.24

 OFFSET: 2.00

 TC-TA -5.06 C

 VAPOR PRESSURE DEFICIT: 5.06 KPA

 UPPER LIMIT: 3.09 C

 CROP WATER STRESS INDEX: 0.17

 RELATIVE HUMIDITY: 19.33%

Figure 18

Data for CWSI Hand Calculation Example

Visiting Fields

Once access tube installation is complete and the refill point has been established, field

irrigation scheduling can be started. Biweekly readings are taken at predetermined

depths. Cool-climate crops require less frequent readings. The readings, in inches of

moisture, are plotted on a graph or entered into a computer. Usually, three

measurements are taken in the first 3 feet of depth. Crops, such as fruit trees, that

have deeper penetrating roots will require additional readings at greater depths. Each

set of readings will give the current moisture content. Consecutive readings will give the

rate of water use by the crop.

Accurate moisture readings are essential to schedule irrigations precisely. The

technician must ensure that the equipment works properly, readings are taken correctly,

and the site is protected. Before going to the field, the technician should verify the

proper operation of the gauge. This is done by taking a measurement on one of the

standardization barrels. The reading should be within ±0.05 in/ft of the barrel's moisture

content, if using the DR-503. The reading with an S-503 should be within plus or minus

one standard deviation of the average count. (The average count was determined

during standardization of the gauge). 
Chapter 5 - Scheduling Irrigations

36

Sample Date: 7-25-83 Crop: Cotton

Field: 5 USBR Slope -1.70

C = Centigrade USBR Intercept 1.90

(Tc-Ta) = -1.70 (VPD) + 1.92 (Equation of Well-Watered Baseline) 

[B]. (Tc-Ta) = 31.94 C - 37.0 C db = -5.06 C (Actual Temperature Depression) 

[A]. Upper Limit Value

Saturation Vapor Pressure of db Temp. (Appendix A) 47.067

Saturation Vapor Pressure of (db Temp. + 1.92) -52.161

Vapor Pressure Difference in MM Hq - 5.094

VPD in mm Hq = -5.094 x constant 1.3331 = VPD in mb - 6.791

VPD in mb = 6.791 ÷ constant 10 = VPD in Kpa - .679

(Tc - Ta) ul = -.679 x slope -1.70 + offset +1.92 + 3.07

[C]. Well-Watered Value

Saturation Vapor Pressure of db Temp. (Appendix A) 47.067

Relative Humidity in Field from Wet- and Dry-Bulb x .193

Existing Vapor Pressure in mm Hg 9.084

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

Saturation Vapor Pressure of db Temp. 47.067

Existing Vapor Pressure in mm Hg - 9.084

Vapor Pressure Deficit in mm Hg 37.983

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

Vapor Pressure Deficit in mm Hg 37.983

Constant x 1.3331

Vapor Pressure Deficit in mb 50.635

Vapor Pressure Deficit in mb ÷ 10 = Vapor Pressure Deficit in Kpa = 5.063

Vapor Pressure Deficit in Kpa = 5.063

(Tc-Ta)ww = 5.063 x (-1.70) + 1.92 - 6.687

CWSI = [B] - [C] = (-5.06) - (-6.687) = .167 or .17 (rounded)

 [A] - [C] ( 3.07) - (-6.687)

Note: If B is a larger number than C and they are both negative, the CWSI will be negative.

Figure 19

Hand Calculating Crop Water Stress Index
Chapter 5 - Scheduling Irrigations

37

Upon arriving at the field, the technician should exercise caution when approaching the

site, placing the gauge on the access tube, and taking readings. This is to insure that

the crop growth around the tube is not trampled. Otherwise, the consumptive use

measured at the site will not represent healthy crop stands in the remainder of the field. 

Protecting the crop is essential in maintaining good relations with the farmer.

Moisture readings are taken at about the 6-inch, 18-inch, and 30-inch depths. These

readings will be centered in the 1st-foot, 2nd-foot, and 3rd-foot zones. Fewer reading

intervals may be required for shallow-rooted crops while deep-rooted crops may require

more reading intervals. Readings are taken according to previously described

procedures. The reading, read directly from the display or determined from a

conversion table, should be written in the space provided and plotted immediately on a

field graph. A sample field graph is shown in Figure 20. The reading can be plotted

while the gauge is measuring the next depth so plotting does not require much

additional time. (Note: Appendix D contains a blank field graph that can be duplicated

as needed for use in the field.)

Plotting readings as they are taken serves several purposes. The chance of an

occasional stray reading or error in interpretation can be quickly spotted and the

measurement retaken. If needed, the next irrigation can be immediately determined at

the site. Use a straight edge to project a line through the last two readings to the refill

line. Read the date where the projected line and the refill line intersect. By noting the

date and the surrounding conditions, the technician may identify unusual conditions. 

Anything unusual should be brought to the farmer's attention. Several crops have been

saved by the alert observations of field technicians.

Before leaving the site, the technician should insure that the probe has been retracted

and securely locked in place in the gauge case. The cap should also be securely

replaced on the tube. Otherwise, irrigation water could fill the tube and damage the

probe the next time a reading is taken. 

Field technicians have noted that readings taken at the access tube site may, in some

cases, not always represent conditions found throughout the majority of the field. The

most frequently occurs when the field is not uniformly irrigated. As a result, some parts

of the field may be under irrigated while other parts are over irrigated. When the

technician suspects that this may be the case, a hand soil probe should be used to

sample several locations in the field and use the "feel method" to determine and

compare moisture contents. When this condition is noted, the farmer should be

advised. This effort may help save a portion of the crop and offers an opportunity to

consult with the farmer on ways to improve the efficiency of the irrigation program.

After measuring all the sites on the assigned route, the technician should submit the

data for computer preparation of schedules, if a computer is being used. Otherwise, the

technician should transfer projected dates and amounts to a summary report sheet that

can be given to the farmer. If printed irrigation schedules are used, the technician

should compare projected dates shown on the printout with the graphs in the field book. 

Any corrections should be entered into the computer. A new schedule should be
Chapter 5 - Scheduling Irrigations

38

Figure 20

Sample Field Graph
Chapter 5 - Scheduling Irrigations

39

printed so the printed dates and amounts agree with the field graphs. A simple

summary form that can be given to the farmers is shown in Figure 21. A blank form is in

Appendix D. A computer-generated irrigation schedule is shown in Figure 22.

Contacting Farmers

Several methods are available to get the completed report or schedule to the farmer. 

The report or schedule can be sent by mail, delivered to the secretary or a family

member, put in farmer's truck, etc. However, the most effective method is by direct

contact. Experience has repeatedly shown in the LC Region that the farmers who most

closely follow the recommendations have received the most frequent personal contact

by the field technicians. Personal contacts can include a walk through the field with the

farmer, a roadside discussion, a meeting at the local coffee shop, or a visit to the

farmer's home or office. Any other means where the technician and farmer can discuss

the farmer's irrigation activities, field and crop conditions, and any other information

about the farmer's overall operation are also appropriate. Regular meeting schedules

are often impossible to establish with farmers. Other means to get scheduling reports to

the farmer in a timely manner will beneficially supplement personal contacts.

Remember, good personal contacts are essential to effective irrigation scheduling.
Chapter 5 - Scheduling Irrigations

40

DATE_________________________ DATE________________________

WATER USER __________________ WATER USER _________________

CONTRACT NO. ________________ CONTRACT NO. _______________

FIELD

NO.

PROJECTED

IRRIG. DATE

REFILL

AMOUNT

FIELD

NO.

PROJECTED

IRRIG. DATE

REFILL

AMOUNT

303-41 (Rev. 5-92) 303-41 (Rev. 5-92)

(File Copy) (Farmer's Copy)

Figure 21

Sample Farmer Report Form
Chapter 5 - Scheduling Irrigations

41

 BUREAU OF INDIAN AFFAIRS

 Route 1 Box 9c

 Parker, AZ 85344

 662-4358

 DATE: APR 26

 CRIT FARMS

 P O BOX 1028

 PARKER AZ 85344

 ------------IRRIGATIONS------------

 FIELD, CROP ------NEXT------ ------LAST------

 AND ACRES ----AMT--- ----AMT---

 ------------ DATE IN. AC-FT DATE IN. AC-FT

 12 ALF 38 5/ 3 5.7 18.0 4/19 4.2 13.3

 16 ALF 37 5/ 3 5.7 17.6 4/19 5.4 16.7

 17 ALF 37 5/ 9 5.7 17.6 4/21 3.0 9.3

 21 ALF 36 4/29 4.0 12.0 4/16 .0 .0

 22 ALF 37 5/ 9 5.6 15.4 4/21 6.8 21.0

 26 ALF 36 5/ 7 5.6 16.8 4/16 11.9 35.7

 27 ALF 36 5/ 7 4.2 12.6 4/18 10.8 32.4

 30 ALF 35 5/ 7 4.0 11.9 4/18 8.7 25.4

 31 ALF 35 5/ 7 5.3 15.5 4/18 11.1 32.4

 41 ALF 38 4/30 4.2 13.2 4/18 6.3 20.0

 45 ALF 37 ***** 4/20 .0 .0

 46 ALF 35 5/ 3 4.0 12.0 4/18 .0 .0

 48 ALF 35 4/29 4.6 13.8 4/18 .0 .0

 49 ALF 38 4/29 3.5 10.9 4/18 .0 .0

 56 ALF 35 4/23* 3.5 10.5 4/14 7.4 21.6

 2- 2 ALF 32 4/27 3.4 9.1 4/14 17.3 46.1

 2- 3 ALF 25 4/26 5.0 10.4 4/13 3.2 6.7

 2- 8 ALF 16 4/26 3.4 4.2 4/14 5.0 6.7

 2-11 ALF 21 4/25* 5.1 8.9 4/13 4.5 7.9

 2-13 ALF 52 4/28 4.2 16.2 4/12 4.2 18.2

 2-16 ALF 29 4/27 4.5 10.9 4/10 8.1 19.6

 2-17 ALF 30 4/27 4.6 11.5 4/10 3.9 9.8

 * - FIELD OVERDUE FOR IRRIGATION

 ***** - IRRIGATION NOT REQUIRED BEFORE MAY 10

Figure 22

Sample Computer Generated Farm Irrigation Schedule
Appendix A

APPENDIX A

Relative Humidity, Percent – Centigrade Temperatures
Appendix A

A-1

Appendix A

Relative Humidity, Percent - Centigrade Temperatures

[Pressure=29.24 in.]

Air

temperature(t)

Depression of wet-bulb thermometer(t-t')

7.6 7.7 7.8 7.9 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 9.0

8.................. 12 11 1098765

9.................. 16 15 14 13 12 11 1098765

10................. 19 18 17 16 15 14 13 12 11 109877 6

11................. 22 21 20 19 18 17 16 15 14 13 13 12 11 10 9

12................. 24 23 22 22 21 20 19 18 17 16 16 15 14 13 13

13................. 27 26 25 24 23 22 22 21 20 19 18 17 17 16 15

14................. 29 28 27 27 26 25 24 23 22 22 21 20 19 18 18

15................. 31 30 29 28 27 27 26 25 24 24 23 22 22 21 20

16................. 33 32 32 31 30 29 29 28 27 26 26 25 24 23 23

17................. 35 34 34 33 32 31 31 30 29 28 28 27 26 26 25

18................. 37 36 35 35 34 33 33 32 31 30 30 29 28 28 27

19................ 39 38 37 36 36 35 34 34 33 32 32 31 30 30 29

20................. 40 39 39 38 37 37 36 35 35 34 33 33 32 31 31

21................. 42 41 40 40 39 38 38 37 36 36 35 34 34 33 32

22................. 43 42 42 41 40 40 39 39 38 37 37 36 35 35 34

23................. 44 44 43 42 42 41 41 40 39 39 38 38 37 36 36

24................. 46 45 44 44 43 43 42 41 41 40 40 39 38 38 37

25................. 47 46 46 45 44 44 43 43 42 41 41 40 40 39 39

26................. 48 47 47 46 46 45 44 44 43 43 42 42 41 40 40

27................. 49 48 48 47 47 46 46 45 44 44 43 43 42 42 41

28................. 50 49 49 48 48 47 47 46 46 45 44 44 43 43 42

29................ 51 50 50 49 49 48 48 47 47 46 46 45 44 44 43

30................. 52 51 51 50 50 49 49 48 48 47 47 46 45 45 44

31................. 53 52 52 51 51 50 50 49 49 48 48 47 47 46 45

32................. 54 53 52 52 51 51 50 50 49 49 48 48 47 47 46

33................. 54 54 53 53 52 52 51 51 50 50 49 49 48 48 47

34................. 55 55 54 54 53 53 52 52 51 51 50 50 49 49 48

35................. 56 55 54 54 54 53 53 52 52 51 51 50 50 49 49

36................. 56 56 55 55 54 54 53 53 53 52 52 51 51 50 50

37................. 57 57 56 56 55 55 54 54 53 53 52 52 51 51 51

38................. 58 57 57 56 56 55 55 55 54 54 53 53 52 52 51

39................. 58 58 57 57 57 56 56 55 55 54 54 53 53 52 52

40................. 59 59 58 58 57 57 56 56 55 54 54 54 54 53 53

41................. 60 59 59 58 58 57 57 56 56 56 55 55 54 54 53

42................. 60 60 59 59 58 58 57 57 57 56 56 55 54 54 54

43................. 61 60 60 59 59 58 58 58 57 57 56 56 55 55 55

44................. 61 61 60 60 59 59 58 58 58 57 57 56 56 56 55
Appendix A

A-2

Appendix A

Relative humidity, percent-centigrade temperatures-Continued

[Pressure=29.24 in.]

Air tempreature(t) Depression of wet-bulb thermometer(t-t')

9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 10.0 10.1 10.2 10.3 10.4 10.5

10.................... 5

11.................... 8 7 6 6 5

12.................... 11 10 10 98765 5

13................... 14 13 13 12 11 10 9 9 8 7665

14................... 17 16 15 15 14 13 12 11 11 109887 6

15................... 20 19 18 17 16 16 15 14 13 13 12 11 11 10 9

16................... 22 21 20 20 19 18 17 17 16 15 15 14 13 13 12

17................... 24 23 23 22 21 21 20 19 18 18 17 16 16 15 14

18................... 26 26 25 24 23 23 22 21 21 20 19 19 18 17 17

19................... 28 28 27 26 26 25 24 24 23 22 22 21 20 20 19

20................... 30 29 29 28 28 27 26 26 25 24 24 23 22 22 21

21................... 32 31 31 30 29 29 28 28 27 26 26 25 24 24 23

22................... 34 33 32 32 31 30 30 29 29 28 28 27 26 26 25

23................... 35 34 34 33 33 32 32 31 30 30 29 29 28 27 27

24................... 37 36 35 35 34 34 33 33 32 31 31 30 30 29 29

25................... 38 37 37 36 36 35 35 34 33 33 32 32 31 31 30

26................... 39 39 38 38 37 37 36 35 35 34 34 33 33 32 32

27................... 41 40 39 39 38 38 37 37 36 36 35 35 34 34 33

28................... 42 41 41 40 40 39 39 38 38 37 36 36 35 35 34

29................... 43 42 42 41 41 40 40 39 39 38 38 37 37 36 36

30................... 44 43 43 42 42 41 41 40 40 39 39 38 38 37 37

31................... 45 44 44 43 43 42 42 41 41 40 40 40 39 39 38

32................... 46 45 45 44 44 43 43 42 42 41 41 41 40 40 39

33................... 47 46 46 45 45 44 44 43 43 42 42 42 41 41 40

34................... 48 47 47 46 46 45 45 44 44 43 43 43 42 42 41

35................... 49 48 48 47 47 46 46 45 45 44 44 44 43 43 42

36................... 49 49 48 48 48 47 47 46 46 45 45 44 44 44 43

37................... 50 50 49 49 48 48 47 47 47 46 46 45 45 44 44

38................... 51 50 50 50 49 49 48 48 47 47 46 46 46 45 45

39................... 52 51 51 50 50 49 49 48 48 48 47 47 46 46 46

40................... 52 52 51 51 51 50 50 49 49 48 48 48 47 47 46

41................... 53 52 52 52 51 51 50 50 50 49 49 48 48 47 47

42................... 53 53 53 52 52 51 51 51 50 50 49 49 48 48 48

43................... 54 54 53 53 52 52 52 51 51 50 50 50 49 49 48

44................... 55 54 54 53 53 53 52 52 51 51 51 50 50 49 49
Appendix A

A-3

Appendix A

Relative humidity, percent-centigrade temperatures-Continued

[Pressure=29.24 in.]

Air tempreature(t) Depression of wet-bulb thermometer(t-t')

10.6 10.7 10.8 10.9 11.0 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 12.0

14........................ 6 5

15........................ 8 87665

16........................ 11 10 109887665

17...................... 14 13 12 12 11 10 10 9 8 87665

18...................... 16 15 15 14 14 13 12 12 11 10 10 9 8 8 7

19...................... 18 18 17 17 16 15 15 14 13 13 12 12 11 10 10

20...................... 21 20 19 19 18 18 17 16 16 15 15 14 13 13 12

21...................... 23 22 22 21 20 20 19 19 18 17 17 16 16 15 14

22...................... 25 24 23 23 22 22 21 20 20 19 19 18 18 17 17

23...................... 26 26 25 25 24 24 23 22 22 21 21 20 20 19 19

24...................... 28 27 27 26 26 25 25 24 24 23 23 22 21 21 20

25...................... 30 29 29 28 28 27 26 26 25 25 24 24 23 23 22

26...................... 31 31 30 30 29 28 28 27 27 26 26 25 25 24 24

27...................... 33 32 32 31 31 30 30 29 29 28 28 27 27 26 26

28...................... 34 33 33 32 32 31 31 30 30 29 29 28 28 27 27

29...................... 35 35 34 34 33 33 32 32 31 31 30 30 29 29 28

30...................... 36 36 35 35 35 34 34 33 33 32 32 31 31 30 30

31...................... 38 37 37 36 36 35 35 34 34 33 33 32 32 32 31

32...................... 39 38 38 37 37 36 36 36 35 35 34 34 33 33 32

33...................... 40 39 39 38 38 37 37 36 36 36 35 35 34 34 33

34...................... 41 40 40 39 39 39 38 38 37 37 36 36 35 35 35

35...................... 42 41 41 40 40 40 39 39 38 38 37 37 37 36 36

36...................... 43 42 42 41 41 40 40 40 39 39 38 38 38 37 37

37...................... 44 43 43 42 42 41 41 41 40 40 39 39 38 38 38

38...................... 44 44 44 43 43 42 42 41 41 41 40 40 39 39 39

39...................... 45 45 44 44 43 43 43 42 42 42 41 41 40 40 39

40...................... 46 46 45 45 44 44 44 43 43 42 42 42 41 40 40

41...................... 47 46 46 45 45 45 44 44 43 43 43 42 42 41 41

42...................... 47 47 46 46 46 45 45 45 44 44 43 43 43 42 42

43...................... 48 48 47 47 46 46 46 45 45 44 44 44 43 43 43

44...................... 49 48 48 47 47 47 46 46 46 45 45 44 44 44 43
Appendix A

A-4

Appendix A

Relative humidity, percent-centigrade temperatures-Continued

[Pressure=29.24 in.]

Air

Temperature

(t)

Depression of wet-bulb thermometer(t-t')

12.1 12.2 12.3 12.4 12.5 12.6 12.7 12.8 12.9 13.0 13.1 13.2 13.3 13.4 13.5

18................ 7655

19................ 99877665

20................ 12 11 10 10998776655

21................ 14 13 13 12 12 11 10 10 9 9 8 8 7 7 6 

22................ 16 15 15 14 14 13 13 12 12 11 10 10 9 9 8 

23................ 18 17 17 16 16 15 15 14 14 13 13 12 12 11 11 

24................ 20 19 19 18 18 17 17 16 16 15 15 14 14 13 13 

25................ 22 21 21 20 20 19 19 18 18 17 17 16 16 15 15 

26................ 23 23 22 22 21 21 20 20 19 19 19 18 18 17 17 

27................ 25 25 24 24 23 23 22 22 21 21 20 20 19 19 18 

28................ 27 26 26 25 25 24 24 23 23 22 22 21 21 20 20 

29................ 28 28 27 27 26 26 25 25 24 24 23 23 22 22 22 

30................ 29 29 28 28 28 27 27 26 26 25 25 24 24 24 23 

31................ 31 30 30 29 29 28 28 28 27 27 26 26 25 25 25 

32................ 32 31 31 31 30 30 29 29 28 28 28 27 27 26 26 

33................ 33 32 32 32 31 31 30 30 30 29 29 28 28 28 27 

34................ 34 34 33 33 32 32 32 31 31 30 30 30 29 29 28 

35................ 35 35 34 34 34 33 33 32 32 32 31 31 30 30 30 

36................ 36 36 35 35 35 34 34 33 33 33 32 32 31 31 31 

37................ 37 37 36 36 36 35 35 34 34 34 33 33 33 32 32 

38................ 38 38 37 37 37 36 36 35 35 35 34 34 33 33 33 

39................ 39 39 38 38 38 37 37 36 36 36 35 35 34 34 34 

40................ 40 40 39 39 38 38 38 37 37 36 36 36 35 35 35 

41................ 41 40 40 40 39 39 39 38 38 37 37 37 36 36 36 

42................ 42 41 41 40 40 40 39 39 39 38 37 37 37 37 36 

43................ 42 42 42 41 41 40 40 40 39 39 39 38 38 38 37 

44................ 43 43 42 42 42 41 41 40 40 40 39 39 39 38 38 
Appendix B

APPENDIX B

Vapor Pressure of Water Below 100 oC
Appendix B

B-1

VAPOR PRESSURE OF WATER BELOW 100°

Pressure of aqueous vapor over water in mm of Hg for temperatures from -15.8 to 100° C

Values for fractional degrees between 50 and 89 were obtained by interpolation.

Temp

°C

0.0 0.2 0.4 0.6 0.8 Temp

°C

0.0 0.2 0.4 0.6 0.8

-15 1.436 1.414 1.390 1.368 1.345 12 10.518 10.658 10.799 10.941 11.085

-14 1.500 1.534 1.511 1.483 1.460 13 11.231 11.379 11.528 11.680 11.833

-13 1.691 1.685 1.637 1.611 1.585 14 11.987 12.444 12.302 12.462 12.624

-12 1.834 1.804 1.776 1.748 1.720 15 12.788 12.953 13.121 13.290 13.461

-11 1.987 1.955 1.924 1.893 1.863 16 13.643 13.809 13.897 14.166 14.347

-10 2.149 2.116 2.084 2.050 2.018 17 14.530 14.715 14.903 15.092 15.284

- 9 2.326 2.289 2.254 2.219 2.184 18 15.477 15.673 15.871 16.071 16.272

- 8 2.514 2.475 2.437 2.399 2.362 19 16.477 16.685 16.894 17.105 17.319

- 7 2.715 2.674 2.633 2.593 2.553 20 17.535 17.753 17.974 18.197 18.422

- 6 2.931 2.887 2.843 2.800 2.757 21 18.650 18.880 19.113 19.349 19.587

- 5 3.163 3.115 3.069 3.022 2.976 22 19.827 20.070 20.316 20.565 20.815

- 4 3.410 3.359 3.309 3.259 3.211 23 21.068 21.234 21.583 21.845 22.110

- 3 3.673 3.620 3.567 3.514 3.461 24 22.377 22.648 22.922 23.198 23.476

- 2 3.956 3.808 3.841 3.785 3.730 25 23.756 24.039 24.326 24.617 24.912

- 1 4.258 4.196 4.135 4.075 4.016 26 25.209 25.509 25.812 26.117 26.426

- 0 4.579 4.513 4.448 4.385 4.320 27 26.739 27.055 27.374 37.696 28.021

 0 4.579 4.647 4.715 4.785 4.855 28 28.349 28.680 29.015 29.354 29.697

 1 4.296 4.998 5.070 5.144 5.219 29 30.043 30.392 30.745 31.102 31.461

 2 5.294 5.370 5.447 5.525 5.605 30 31.824 32.191 32.561 32.934 33.312

 3 5.685 5.766 5.848 5.931 6.015 31 33.695 34.082 34.471 34.864 35.261

 4 6.101 6.187 6.274 6.363 6.453 32 35.663 36.068 36.477 36.891 37.308

 5 6.543 6.635 6.728 6.822 6.917 33 37.729 38.155 38.584 39.018 39.457

 6 7.013 7.111 7.209 7.309 7.411 34 39.898 40.344 40.796 41.251 41.710

 7 7.513 7.617 7.722 7.828 7.936 35 42.175 42.644 43.117 43.595 44.078

 8 8.045 8.155 8.267 8.380 8.494 36 44.563 45.054 45.549 46.050 46.556

 9 8.609 8.727 8.845 8.965 9.086 37 47.067 47.582 48.102 48.627 49.157

 10 9.209 9.333 9.458 9.585 9.714 38 49.692 50.231 50.774 51.323 51.879

 11 9.844 9.976 10.109 10.244 10.380 39 52.442 53.009 53.580 54.156 54.737
Appendix B

B-2

VAPOR PRESSURE OF WATER BELOW 100°-Continued

Pressure of aqueous vapor over water in mm of Hg for temperatures from -15.8 to 100° C

Values for fractional degrees between 50 and 89 were obtained by interpolation.

Temp

°C

0.0 0.2 0.4 0.6 0.8 Temp

°C

0.0 0.2 0.4 0.6 0.8

40 55.324 55.91 56.51 57.11 57.72 71 243.9 246.0 248.2 250.3 252.4

41 58.34 58.96 59.58 60.22 60.86 72 254.6 256.8 259.0 261.2 263.4

42 61.50 62.14 62.80 63.46 64.12 73 265.7 268.0 270.2 272.6 274.8

43 64.80 65.48 66.16 66.86 67.56 74 277.2 279.4 281.8 284.2 286.6

44 68.26 68.97 69.69 70.41 71.14 75 289.1 291.5 294.0 296.4 298.8

45 71.88 72.62 73.36 74.12 74.88 76 301.4 303.8 306.4 308.9 311.4

46 75.65 76.43 77.21 78.00 78.80 77 314.1 316.6 319.2 322.0 324.6

47 79.60 80.41 81.23 82.05 82.87 78 327.3 330.0 332.8 335.8 338.2

48 83.71 84.56 85.42 80.28 87.14 79 341.0 343.8 346.6 349.4 352.2

49 88.02 38.90 39.90 90.69 91.59 80 355.1 358.0 361.0 363.8 366.8

50 92.51 93.5 94.4 95.3 96.3 81 369.7 372.6 375.6 378.8 381.8

51 97.20 98.2 99.1 100.1 101.1 82 384.9 388.0 391.2 394.4 397.4

52 102.09 103.1 104.1 105.1 106.2 83 400.6 403.8 407.0 410.2 413.6

53 107.20 108.2 109.3 110.4 111.4 84 416.8 420.2 423.6 426.8 430.2

54 112.51 113.6 114.7 115.8 116.9 85 433.6 437.0 440.4 444.0 447.5

55 118.04 119.1 120.3 121.5 122.6 86 450.9 454.4 458.0 461.6 465.2

56 123.80 125.0 126.2 127.4 128.6 87 468.7 472.4 476.0 479.8 483.4

57 129.82 131.0 132.3 133.5 134.7 88 487.1 491.0 494.7 498.5 502.2

58 136.08 137.3 138.5 139.9 141.2 89 506.1 510.0 513.9 517.8 521.8

59 142.60 143.9 145.2 146.6 148.0 90 525.76 529.77 533.80 537.86 541.95

60 149.38 150.7 152.1 153.5 155.0 91 546.05 550.18 554.35 558.53 562.75

61 156.43 157.8 159.3 160.8 162.3 92 566.99 571.26 575.55 579.87 584.22

62 163.77 165.2 166.8 168.3 169.8 93 538.60 593.00 597.43 601.89 600.38

63 171.38 172.9 174.5 176.1 177.7 94 610.90 615.44 620.01 624.61 629.24

64 179.31 180.9 182.5 184.2 185.8 95 633.90 638.58 643.30 648.05 652.82

65 187.54 189.2 190.9 192.6 194.3 96 657.62 662.45 667.31 672.20 677.12

66 196.09 197.8 199.5 201.3 203.1 97 682.07 687.04 692.05 697.10 702.17

67 204.96 206.8 208.6 210.5 212.3 98 707.27 712.40 717.56 722.75 727.98

68 214.17 216.0 218.0 219.9 221.8 99 733.24 738.24 743.85 749.20 754.58

69 223.73 225.7 227.7 229.7 231.7 100 760.00 765.45 770.93 776.44 782.00

70 233.7 235.7 237.7 239.7 241.8 101 787.57 793.18 798.82 804.50 810.21
Appendix C

APPENDIX C

Equipment Drawings and Specifications
Appendix C

C-1

Figure C-1. Neutron Moisture Gauge Access Tube Adapter
Appendix D

D-1

APPENDIX D

Blank Field Data Sheets



Appendix E - Using Program VEGY

APPENDIX E

Using Program VEGY
Appendix E - Using Program VEGY

E-1

USING PROGRAM VEGY

Program VEGY is intended to assist in the computation of the Crop Water Stress Index

(CWSI). VEGY was originally written in FORTRAN by the Yuma Area Office in about

1985 for use on the VAX computer. The version discussed here has been converted to

BASIC for use on IBM-compatible, personal computers. It can be run with GWBASIC or

QBASIC on MS-DOS computers. The program listing is also included for those

venturesome individuals who wish to enter the program by hand or convert it to Visual

Basic so that it can be run on MS-Windows computers.

Program VEGY is a menu-driven program that presents the user with fill-in-the-blanks

screen images for data entry. From the main menu, the user can do the following:

1. Create a new data file,

2. Add data to an existing data file,

3. Correct data in an existing data file,

4. Compute the CWSI,

5. Compute the slope and offset for a crop, and

6. Exit the program.

Program VEGY and its accompanying crop name file, CROPS.DAT, can be located in

any convenient subdirectory on the hard drive. It can also be run from a floppy disk if

desired. If other Reclamation WMC software programs are in use, VEGY should be

located in the same subdirectory.

To start Program VEGY, use the appropriate commands under the following

circumstances:

GWBASIC (early versions of MS-DOS) - Type: GWBASIC VEGY

QBASIC (MS-DOS ver. 5.0 & later) - Type: QBASIC /R VEGY

Compiled Program - Type: VEGY

VEGY will display a main menu showing the options listed above. After selecting an

option, VEGY will ask for the name of the data file containing existing data or the name

of a new file being created. Use an easily understood and remembered name like

VEGYDATA.DAT. You may want to use separate files for each batch of data being

processed, separate files for different crops, etc. A word of caution here. Data from

various crops can be mixed when computing the CWSI but should not be mixed when

computing new a slope and offset for a crop. Use a separate file for each crop.
Appendix E - Using Program VEGY

E-2

Program Listing - VEGY.BAS

10 ' - PROGRAM VEGY.BAS

20 ' DATA ENTRY PROGRAM CREATED BY DATASYS

30 ' AUTHOR: Michael Stuver

40 ' DATE: October 24, 1995

50 DIM SL$(30),DL$(50),CROP$(100),VALID$(16),SKEY$(50),RPOINTER(50)

60 FF$=CHR$(12)

70 NP=1

80 SCREEN 0

90 COLOR 15,1

100 FOR I=1 TO 20 

110 READ SL$(I)

120 NEXT I

130 FOR I=1 TO 16

140 READ VALID$(I)

150 NEXT I

160 DATA " Program VEGY Data Entry Form"

170 DATA ""

180 DATA ""

190 DATA "Sampling Date (7/21/95 = 072195): ....... "

200 DATA ""

210 DATA "Sampling Time (8:15am = 0815 & 2:15pm = 1415): ...."

220 DATA ""

230 DATA "Crop Code: .. Field designation: .........."

240 DATA ""

250 DATA "Dry-Bulb Temperature (Deg C): ..... Wet-Bulb Temperature (Deg C): ....."

260 DATA ""

270 DATA " Temperatures (Deg C)"

280 DATA " (1): ..... (2): ..... (3): ..... (4): ..... "

290 DATA " (5): ..... (6): ..... (7): ..... (8): ....."

300 DATA ""

310 DATA "Wind Speed: .. Wind Direction: ..."

320 DATA ""

330 DATA "Slope: ..... Offset: ....."

340 DATA ""

350 DATA "Data Quality Code (1=good, 2=fair, 3=poor): .."

360 DATA "N ","NNE","NE ","ENE","E ","ESE","SE ","SSE"

370 DATA "S ","SSW","SW ","WSW","W ","WNW","NW ","NNW"

380 RESTORE

390 OPEN "I",1,"CROPS.DAT"

400 IF EOF(1) THEN 430

410 INPUT#1,I,CROP$(I),Z$

420 GOTO 400

430 CLOSE(1)

440 CLS

450 PRINT "PROGRAM VEGY PC Ver. 1.0 25 October 1995"

460 PRINT

470 PRINT " MAIN MENU"

480 PRINT

490 PRINT " 1 - Start new data file"

500 PRINT " 2 - Add data to existing file"

510 PRINT " 3 - Correct data in existing file"

520 PRINT " 4 - Compute and print CWSI reports"

530 PRINT " 5 - Compute new Slope and Offset"

540 PRINT " (Do not mix data for several crops in"

550 PRINT " the same data file. Use separate Files.)"

560 PRINT " 6 - Exit"

570 PRINT

580 PRINT " Please Enter your choice: ";

590 COLOR 14,1

600 LINE INPUT A$

610 COLOR 15,1

620 SEL=VAL(A$)
Appendix E - Using Program VEGY

E-3

630 IF SEL>0 AND SEL<=9 THEN 660

640 PRINT CHR$(7):GOSUB 10120

650 GOTO 580

660 ON SEL GOTO 680,870,1120,1490,1650,1780

670 '

680 ' CHOICE 1 - START NEW DATA FILE

690 '

700 K=1

710 PRINT

720 PRINT "Enter name of data file: ";

730 COLOR 14,1

740 LINE INPUT D$

750 COLOR 15,1

760 CLS

770 FOR I=1 TO 20 

780 PRINT SL$(I)

790 NEXT I

800 'OPEN "O",3,D$

810 GOSUB 1830 ' CALL DATA ENTRY SUBROUTINE

820 IF QUIT=1 THEN 830 ELSE 810

830 NR=K-1

840 'GOSUB 10030 ' PRINT UPDATED DATA FILE

845 GOSUB 10200 ' SORT AND PRINT UPDATED DATA FILE

850 GOTO 440

860 '

870 ' CHOICE 2 - ADD DATA TO EXISTING FILE

880 '

890 PRINT

900 PRINT "Enter name of data file: ";

910 COLOR 14,1

920 LINE INPUT D$

930 COLOR 15,1

940 OPEN "I",#1,D$

950 K=0

960 IF EOF(1) THEN 1000

970 K=K+1

980 LINE INPUT#1,DL$(K)

990 GOTO 960

1000 CLS

1010 K=K+1

1020 FOR I=1 TO 20 

1030 PRINT SL$(I)

1040 NEXT I

1050 QUIT =0 

1060 GOSUB 1830 ' CALL DATA ENTRY SUBROUTINE

1070 IF QUIT=1 THEN 1080 ELSE 1060

1080 CLOSE

1081 NR=K-1

1082 'LPRINT NR

1090 'GOSUB 10030 ' PRINT UPDATED DATA FILE

1091 GOSUB 10200 ' SORT AND PRINT UPDATED DATA FILE

1100 GOTO 440

1110 '

1120 ' CHOICE 3 - SUBROUTINE TO CORRECT EXISTING DATA

1130 '

1140 IF D$>"" THEN 1200

1150 PRINT

1160 PRINT "Enter name of data file: ";

1170 COLOR 14,1

1180 LINE INPUT D$

1190 COLOR 15,1

1200 OPEN "I",1,D$

1210 K=0

1220 IF EOF(1) THEN 1260

1230 K=K+1
Appendix E - Using Program VEGY

E-4

1240 LINE INPUT#1,DL$(K)

1250 GOTO 1220

1260 CLOSE

1270 NR=K

1280 CLS

1290 FOR I=1 TO 20 

1300 PRINT SL$(I)

1310 NEXT I

1320 FOR K=1 TO NR

1330 GOSUB 6790

1340 LOCATE 23,1:PRINT "Is this record correct (Y/N)? Y ";

1350 LOCATE 23,31

1360 COLOR 14,1

1370 LINE INPUT B$

1380 COLOR 15,1

1390 LOCATE 23,1:PRINT " "

1400 IF B$="y" OR B$="Y" THEN 1450

1410 IF B$="" THEN 1450

1420 QUIT=0

1430 GOSUB 1830

1440 IF QUIT=1 THEN 1460

1450 NEXT K

1460 'GOSUB 10030 ' PRINT UPDATED DATA FILE

1461 GOSUB 10200 ' SORT AND PRINT UPDATED DATA FILE

1470 GOTO 440

1480 '

1490 ' CHOICE 4 - COMPUTE AND PRINT CWSI

1500 '

1510 IF D$<="" THEN 

1520 PRINT

1530 PRINT "Enter name of data file: ";

1540 COLOR 14,1

1550 LINE INPUT D$

1560 COLOR 15,1

1570 END IF

1580 GOSUB 7230

1590 LPRINT FF$

1600 LOCATE 23,1,1

1610 PRINT " "

1620 CLOSE

1630 GOTO 440

1640 '

1650 ' CHOICE 5 - COMPUTE NEW SLOPE AND OFFSET

1660 '

1670 IF D$>"" THEN 1730

1680 PRINT

1690 PRINT "Enter name of data file: ";

1700 COLOR 14,1

1710 LINE INPUT D$

1720 COLOR 15,1

1730 OPEN "I",2,D$

1740 GOSUB 8760

1750 CLOSE

1760 GOTO 440

1770 '

1780 ' CHOICE 6 - EXIT PROGRAM

1790 '

1800 LOCATE 23,1,1

1810 PRINT " "

1820 SYSTEM

1830 '

1840 ' --- SUBROUTINE TO ENTER OR CORRECT ONE LINE OF DATA

1850 '

1860 ' - Sampling Date

1870 ' - FIELD 1 INTEGER, SIZE I 7 REPEATED WITH 'ENTER'
Appendix E - Using Program VEGY

E-5

1880 '

1890 LOCATE 23,1:PRINT "ENTER '\' TO END DATA ENTRY ";

1900 LOCATE 4,1:PRINT MID$(SL$(4),1,42);

1910 LOCATE 4, 36,1

1920 COLOR 14,1

1930 LINE INPUT I$

1940 COLOR 15,1

1950 IF LEFT$(I$,1)="\" THEN 1960 ELSE 1980

1960 QUIT=1

1970 RETURN 

1980 Z=LEN(I$):IF Z=0 THEN 2140

1990 Z=LEN(I$)

2000 FOR J=1 TO Z

2010 IF MID$(I$,J,1)= CHR$(45) THEN 2040 

2020 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 2040 

2030 PRINT CHR$(7):GOSUB 10120:GOTO 1830 

2040 NEXT J

2050 IF Z=5 THEN 

2060 F1$=" 0"+I$

2070 GOTO 2140

2080 END IF

2090 IF Z=6 THEN

2100 F1$=" "+I$

2110 GOTO 2140

2120 END IF

2130 GOTO 2030

2140 IF MID$(F1$,2,2)<"01" OR MID$(F1$,2,2)>"12" THEN 2030

2150 IF MID$(F1$,4,2)<"01" OR MID$(F1$,4,2)>"31" THEN 2030

2160 COLOR 14,1

2170 LOCATE 4,36,1:PRINT USING"\ \";F1$

2180 COLOR 15,1

2190 LOCATE 22,1:PRINT " "

2200 '

2210 ' - Sampling Time

2220 ' - FIELD 2 INTEGER, SIZE I 4 REPEATED WITH 'ENTER'

2230 '

2240 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

2250 LOCATE 6,1:PRINT MID$(SL$(6),1,52);

2260 LOCATE 6, 49,1

2270 COLOR 14,1

2280 LINE INPUT I$

2290 COLOR 15,1

2300 IF LEFT$(I$,1)="\" THEN 1830 

2310 Z=LEN(I$):IF Z=0 THEN 2390 

2320 Z=LEN(I$)

2330 FOR J=1 TO Z

2340 IF MID$(I$,J,1)= CHR$(45) THEN 2370 

2350 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 2370 

2360 PRINT CHR$(7):GOSUB 10120:GOTO 2200 

2370 NEXT J

2380 F2=VAL(I$)

2390 IF F2<500 OR F2>2000 THEN 2360

2400 COLOR 14,1

2410 LOCATE 6,49,1:PRINT USING"####";F2

2420 COLOR 15,1

2430 LOCATE 22,1:PRINT " "

2440 F2$=" "

2450 RSET F2$=STR$(F2)

2460 '

2470 ' - Crop Code

2480 ' - FIELD 3 INTEGER, SIZE I 2 REPEATED WITH 'ENTER'

2490 '

2500 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

2510 LOCATE 8,1:PRINT MID$(SL$(8),1,36);

2520 LOCATE 8, 13,1
Appendix E - Using Program VEGY

E-6

2530 COLOR 14,1

2540 LINE INPUT I$

2550 COLOR 15,1

2560 IF LEFT$(I$,1)="\" THEN 2200 

2570 Z=LEN(I$):IF Z=0 THEN 2650 

2580 Z=LEN(I$)

2590 FOR J=1 TO Z

2600 IF MID$(I$,J,1)= CHR$(45) THEN 2630 

2610 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 2630 

2620 PRINT CHR$(7):GOSUB 10120:GOTO 2460 

2630 NEXT J

2640 F3=VAL(I$)

2650 IF F3<1 OR F3>99 THEN 2620

2660 COLOR 14,1

2670 LOCATE 8,13,1:PRINT USING"## \ \";F3,CROP$(F3)

2680 COLOR 15,1

2690 LOCATE 22,1:PRINT " "

2700 F3$=" "

2710 RSET F3$=STR$(F3)

2720 F3$=MID$(F3$,3,2)

2730 '

2740 ' - Field Number

2750 ' - FIELD 4 ALPHA, SIZE A 10 REPEATED WITH 'ENTER'

2760 '

2770 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

2780 LOCATE 8,37:PRINT MID$(SL$(8),37,32);

2790 LOCATE 8, 58,1

2800 COLOR 14,1

2810 LINE INPUT I$

2820 COLOR 15,1

2830 IF LEFT$(I$,1)="\" THEN 2460 

2840 Z=LEN(I$):IF Z=0 THEN 2870 

2850 F4$=" "

2860 LSET F4$=I$

2870 COLOR 14,1

2880 LOCATE 8,58,1:PRINT F4$

2890 COLOR 15,1

2900 LOCATE 22,1:PRINT " "

2910 '

2920 ' - Dry-bulb Temp

2930 ' - FIELD 5 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

2940 '

2950 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

2960 LOCATE 10,1:PRINT MID$(SL$(10),1,36);

2970 LOCATE 10, 32,1

2980 COLOR 14,1

2990 LINE INPUT I$

3000 COLOR 15,1

3010 IF LEFT$(I$,1)="\" THEN 2730 

3020 Z=LEN(I$):IF Z=0 THEN 3100 

3030 Z=LEN(I$)

3040 FOR J=1 TO Z

3050 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 3080 

3060 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 3080 

3070 PRINT CHR$(7):GOSUB 10120:GOTO 2910 

3080 NEXT J

3090 F5=VAL(I$)

3100 IF F5<2 OR F5>54 THEN 3070

3110 COLOR 14,1

3120 LOCATE 10,32,1:PRINT USING"###.#";F5

3130 COLOR 15,1

3140 LOCATE 22,1:PRINT " "

3150 F5$=" "

3160 RSET F5$=STR$(F5*10)

3170 '
Appendix E - Using Program VEGY

E-7

3180 ' - Wet-bulb Temp

3190 ' - FIELD 6 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

3200 '

3210 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

3220 LOCATE 10,37:PRINT MID$(SL$(10),37,38);

3230 LOCATE 10, 70,1

3240 COLOR 14,1

3250 LINE INPUT I$

3260 COLOR 15,1

3270 IF LEFT$(I$,1)="\" THEN 2910 

3280 Z=LEN(I$):IF Z=0 THEN 3360 

3290 Z=LEN(I$)

3300 FOR J=1 TO Z

3310 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 3340 

3320 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 3340 

3330 PRINT CHR$(7):GOSUB 10120:GOTO 3170 

3340 NEXT J

3350 F6=VAL(I$)

3360 IF F6<2 OR F6>54 THEN 3330

3370 COLOR 14,1

3380 LOCATE 10,70,1:PRINT USING"###.#";F6

3390 COLOR 15,1

3400 LOCATE 22,1:PRINT " "

3410 F6$=" "

3420 RSET F6$=STR$(F6*10)

3430 '

3440 ' - Temp 1

3450 ' - FIELD 7 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

3460 '

3470 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

3480 LOCATE 13,1:PRINT MID$(SL$(13),1,19);

3490 LOCATE 13, 15,1

3500 COLOR 14,1

3510 LINE INPUT I$

3520 COLOR 15,1

3530 IF LEFT$(I$,1)="\" THEN 3170 

3540 Z=LEN(I$):IF Z=0 THEN 3620 

3550 Z=LEN(I$)

3560 FOR J=1 TO Z

3570 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 3600 

3580 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 3600 

3590 PRINT CHR$(7):GOSUB 10120:GOTO 3430 

3600 NEXT J

3610 F7=VAL(I$)

3620 IF F7<2 OR F7>54 THEN 3590

3630 COLOR 14,1

3640 LOCATE 13,15,1:PRINT USING"###.#";F7

3650 COLOR 15,1

3660 LOCATE 22,1:PRINT " "

3670 F7$=" "

3680 RSET F7$=STR$(F7*10)

3690 '

3700 ' - Temp 2

3710 ' - FIELD 8 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

3720 '

3730 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

3740 LOCATE 13,20:PRINT MID$(SL$(13),20,15);

3750 LOCATE 13, 30,1

3760 COLOR 14,1

3770 LINE INPUT I$

3780 COLOR 15,1

3790 IF LEFT$(I$,1)="\" THEN 3430 

3800 Z=LEN(I$):IF Z=0 THEN 3880 

3810 Z=LEN(I$)

3820 FOR J=1 TO Z
Appendix E - Using Program VEGY

E-8

3830 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 3860 

3840 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 3860 

3850 PRINT CHR$(7):GOSUB 10120:GOTO 3690 

3860 NEXT J

3870 F8=VAL(I$)

3880 IF F8<2 OR F8>54 THEN 3850

3890 COLOR 14,1

3900 LOCATE 13,30,1:PRINT USING"###.#";F8

3910 COLOR 15,1

3920 LOCATE 22,1:PRINT " "

3930 F8$=" "

3940 RSET F8$=STR$(F8*10)

3950 '

3960 ' - Temp 3

3970 ' - FIELD 9 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

3980 '

3990 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

4000 LOCATE 13,35:PRINT MID$(SL$(13),35,15);

4010 LOCATE 13, 45,1

4020 COLOR 14,1

4030 LINE INPUT I$

4040 COLOR 15,1

4050 IF LEFT$(I$,1)="\" THEN 3690 

4060 Z=LEN(I$):IF Z=0 THEN 4140 

4070 Z=LEN(I$)

4080 FOR J=1 TO Z

4090 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 4120 

4100 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 4120 

4110 PRINT CHR$(7):GOSUB 10120:GOTO 3950 

4120 NEXT J

4130 F9=VAL(I$)

4140 IF F9<2 OR F9>54 THEN 4110

4150 COLOR 14,1

4160 LOCATE 13,45,1:PRINT USING"###.#";F9

4170 COLOR 15,1

4180 LOCATE 22,1:PRINT " "

4190 F9$=" "

4200 RSET F9$=STR$(F9*10)

4210 '

4220 ' - Temp 4

4230 ' - FIELD 10 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

4240 '

4250 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

4260 LOCATE 13,50:PRINT MID$(SL$(13),50,15);

4270 LOCATE 13, 60,1

4280 COLOR 14,1

4290 LINE INPUT I$

4300 COLOR 15,1

4310 IF LEFT$(I$,1)="\" THEN 3950 

4320 Z=LEN(I$):IF Z=0 THEN 4400 

4330 Z=LEN(I$)

4340 FOR J=1 TO Z

4350 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 4380 

4360 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 4380 

4370 PRINT CHR$(7):GOSUB 10120:GOTO 4210 

4380 NEXT J

4390 F10=VAL(I$)

4400 IF F10<2 OR F10>54 THEN 4370

4410 COLOR 14,1

4420 LOCATE 13,60,1:PRINT USING"###.#";F10

4430 COLOR 15,1

4440 LOCATE 22,1:PRINT " "

4450 F10$=" "

4460 RSET F10$=STR$(F10*10)

4470 '
Appendix E - Using Program VEGY

E-9

4480 ' - Temp 5

4490 ' - FIELD 11 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

4500 '

4510 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

4520 LOCATE 14,1:PRINT MID$(SL$(14),1,19);

4530 LOCATE 14, 15,1

4540 COLOR 14,1

4550 LINE INPUT I$

4560 COLOR 15,1

4570 IF LEFT$(I$,1)="\" THEN 4210 

4580 Z=LEN(I$):IF Z=0 THEN 4660 

4590 Z=LEN(I$)

4600 FOR J=1 TO Z

4610 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 4640 

4620 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 4640 

4630 PRINT CHR$(7):GOSUB 10120:GOTO 4470 

4640 NEXT J

4650 F11=VAL(I$)

4660 IF F11<2 OR F11>54 THEN 4630

4670 COLOR 14,1

4680 LOCATE 14,15,1:PRINT USING"###.#";F11

4690 COLOR 15,1

4700 LOCATE 22,1:PRINT " "

4710 F11$=" "

4720 RSET F11$=STR$(F11*10)

4730 '

4740 ' - Temp 6

4750 ' - FIELD 12 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

4760 '

4770 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

4780 LOCATE 14,20:PRINT MID$(SL$(14),20,15);

4790 LOCATE 14, 30,1

4800 COLOR 14,1

4810 LINE INPUT I$

4820 COLOR 15,1

4830 IF LEFT$(I$,1)="\" THEN 4470 

4840 Z=LEN(I$):IF Z=0 THEN 4920 

4850 Z=LEN(I$)

4860 FOR J=1 TO Z

4870 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 4900 

4880 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 4900 

4890 PRINT CHR$(7):GOSUB 10120:GOTO 4730 

4900 NEXT J

4910 F12=VAL(I$)

4920 IF F12<2 OR F12>54 THEN 4890

4930 COLOR 14,1

4940 LOCATE 14,30,1:PRINT USING"###.#";F12

4950 COLOR 15,1

4960 LOCATE 22,1:PRINT " "

4970 F12$=" "

4980 RSET F12$=STR$(F12*10)

4990 '

5000 ' - Temp 7

5010 ' - FIELD 13 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

5020 '

5030 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

5040 LOCATE 14,35:PRINT MID$(SL$(14),35,15);

5050 LOCATE 14, 45,1

5060 COLOR 14,1

5070 LINE INPUT I$

5080 COLOR 15,1

5090 IF LEFT$(I$,1)="\" THEN 4730 

5100 Z=LEN(I$):IF Z=0 THEN 5180 

5110 Z=LEN(I$)

5120 FOR J=1 TO Z
Appendix E - Using Program VEGY

E-10

5130 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 5160 

5140 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 5160 

5150 PRINT CHR$(7):GOSUB 10120:GOTO 4990 

5160 NEXT J

5170 F13=VAL(I$)

5180 IF F13<2 OR F13>54 THEN 5150

5190 COLOR 14,1

5200 LOCATE 14,45,1:PRINT USING"###.#";F13

5210 COLOR 15,1

5220 LOCATE 22,1:PRINT " "

5230 F13$=" "

5240 RSET F13$=STR$(F13*10)

5250 '

5260 ' - Temp 8

5270 ' - FIELD 14 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

5280 '

5290 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

5300 LOCATE 14,50:PRINT MID$(SL$(14),50,15);

5310 LOCATE 14, 60,1

5320 COLOR 14,1

5330 LINE INPUT I$

5340 COLOR 15,1

5350 IF LEFT$(I$,1)="\" THEN 4990 

5360 Z=LEN(I$):IF Z=0 THEN 5440 

5370 Z=LEN(I$)

5380 FOR J=1 TO Z

5390 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 5420 

5400 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 5420 

5410 PRINT CHR$(7):GOSUB 10120:GOTO 5250 

5420 NEXT J

5430 F14=VAL(I$)

5440 IF F14<2 OR F14>54 THEN 5410

5450 COLOR 14,1

5460 LOCATE 14,60,1:PRINT USING"###.#";F14

5470 COLOR 15,1

5480 LOCATE 22,1:PRINT " "

5490 F14$=" "

5500 RSET F14$=STR$(F14*10)

5510 '

5520 ' - Wind Speed

5530 ' - FIELD 15 INTEGER, SIZE I 2 REPEATED WITH 'ENTER'

5540 '

5550 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

5560 LOCATE 16,1:PRINT MID$(SL$(16),1,15);

5570 LOCATE 16, 14,1

5580 COLOR 14,1

5590 LINE INPUT I$

5600 COLOR 15,1

5610 IF LEFT$(I$,1)="\" THEN 5250 

5620 Z=LEN(I$):IF Z=0 THEN 5700 

5630 Z=LEN(I$)

5640 FOR J=1 TO Z

5650 IF MID$(I$,J,1)= CHR$(45) THEN 5680 

5660 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 5680 

5670 PRINT CHR$(7):GOSUB 10120:GOTO 5510 

5680 NEXT J

5690 F15=VAL(I$)

5700 IF F15<0 OR F15>99 THEN 5670

5710 COLOR 14,1

5720 LOCATE 16,14,1:PRINT USING"##";F15

5730 COLOR 15,1

5740 LOCATE 22,1:PRINT " "

5750 F15$=" "

5760 RSET F15$=MID$(STR$(F15),2,2)

5770 '
Appendix E - Using Program VEGY

E-11

5780 ' - Wind Direction

5790 ' - FIELD 16 ALPHA, SIZE A 3 REPEATED WITH 'ENTER'

5800 '

5810 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

5820 LOCATE 16,16:PRINT MID$(SL$(16),16,43);

5830 LOCATE 16, 56,1

5840 COLOR 14,1

5850 LINE INPUT I$

5860 COLOR 15,1

5870 IF LEFT$(I$,1)="\" THEN 5510 

5880 Z=LEN(I$):IF Z=0 THEN 5910 

5890 F16$=" "

5900 MID$(F16$,1, 3 )=I$

5910 FOR I=1 TO 16

5920 IF F16$=VALID$(I) THEN 5960

5930 NEXT I

5940 PRINT CHR$(7):GOSUB 10120

5950 GOTO 5770

5960 COLOR 14,1

5970 LOCATE 16,56,1:PRINT MID$(F16$,1,3)

5980 COLOR 15,1

5990 LOCATE 22,1:PRINT " "

6000 '

6010 ' - Slope

6020 ' - FIELD 17 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

6030 '

6040 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

6050 LOCATE 18,1:PRINT MID$(SL$(18),1,13);

6060 LOCATE 18, 9,1

6070 COLOR 14,1

6080 LINE INPUT I$

6090 COLOR 15,1

6100 IF LEFT$(I$,1)="\" THEN 5770 

6110 Z=LEN(I$):IF Z=0 THEN 6190 

6120 Z=LEN(I$)

6130 FOR J=1 TO Z

6140 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 6170 

6150 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 6170 

6160 PRINT CHR$(7):GOSUB 10120:GOTO 6000 

6170 NEXT J

6180 F17=VAL(I$)

6190 COLOR 14,1

6200 LOCATE 18,9,1:PRINT USING"##.##";F17

6210 COLOR 15,1

6220 LOCATE 22,1:PRINT " "

6230 F17$=STR$(F17*100)

6240 '

6250 ' - Offset

6260 ' - FIELD 18 DECIMAL, SIZE F 5.1 REPEATED WITH 'ENTER'

6270 '

6280 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

6290 LOCATE 18,14:PRINT MID$(SL$(18),14,39);

6300 LOCATE 18, 48,1

6310 COLOR 14,1

6320 LINE INPUT I$

6330 COLOR 15,1

6340 IF LEFT$(I$,1)="\" THEN 6000 

6350 Z=LEN(I$):IF Z=0 THEN 6430 

6360 Z=LEN(I$)

6370 FOR J=1 TO Z

6380 IF MID$(I$,J,1)= CHR$(45) OR MID$(I$,J,1)=CHR$(46) THEN 6410 

6390 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 6410 

6400 PRINT CHR$(7):GOSUB 10120:GOTO 6240 

6410 NEXT J

6420 F18=VAL(I$)
Appendix E - Using Program VEGY

E-12

6430 COLOR 14,1

6440 LOCATE 18,48,1:PRINT USING"##.##";F18

6450 COLOR 15,1

6460 LOCATE 22,1:PRINT " "

6470 F18$=STR$(F18*100)

6480 '

6490 ' - Data Quality Code

6500 ' - FIELD 19 INTEGER, SIZE I 2 REPEATED WITH 'ENTER'

6510 '

6520 LOCATE 23,1:PRINT "ENTER '\' TO BACKSPACE ONE FIELD ";

6530 LOCATE 20,1:PRINT MID$(SL$(20),1,47);

6540 LOCATE 20, 46,1

6550 COLOR 14,1

6560 LINE INPUT I$

6570 COLOR 15,1

6580 IF LEFT$(I$,1)="\" THEN 6240 

6590 Z=LEN(I$):IF Z=0 THEN 6670 

6600 Z=LEN(I$)

6610 FOR J=1 TO Z

6620 IF MID$(I$,J,1)= CHR$(45) THEN 6650 

6630 IF MID$(I$,J,1)>CHR$(47) AND MID$(I$,J,1)<CHR$(58) THEN 6650 

6640 PRINT CHR$(7):GOSUB 10120:GOTO 6480 

6650 NEXT J

6660 F19=VAL(I$)

6670 IF F19<1 OR F19>3 THEN 6640

6680 COLOR 14,1

6690 LOCATE 20,46,1:PRINT USING"##";F19

6700 COLOR 15,1

6710 LOCATE 22,1:PRINT " "

6720 F19$=STR$(F19)

6730 LOCATE 23,1,1

6740 PRINT" "

6750 DL$(K)=F1$+F2$+F3$+F4$+F5$+F6$+F7$+F8$+F9$+F10$+F11$+F12$+F13$+F14$

6760 DL$(K)=DL$(K)+F15$+F16$+F17$+F18$+F19$

6761 K=K+1

6770 RETURN

6780 '

6790 '----- SUBROUTINE TO DISPLAY DATA FOR CORRECTION

6800 '

6810 COLOR 7,1

6820 F1$=MID$(DL$(K),1,7)

6830 LOCATE 4,36,1:PRINT USING"\ \";F1$

6840 F2=VAL(MID$(DL$(K),9,4))

6850 LOCATE 6,49,1:PRINT USING"####";F2

6860 F3=VAL(MID$(DL$(K),13,2))

6870 LOCATE 8,13,1:PRINT USING"## \ \";F3,CROP$(F3)

6880 F4$=MID$(DL$(K),15,10)

6890 LOCATE 8,58,1:PRINT F4$

6900 F5=VAL(MID$(DL$(K),25,4))/10

6910 LOCATE 10,32,1:PRINT USING"###.#";F5

6920 F6=VAL(MID$(DL$(K),29,4))/10

6930 LOCATE 10,70,1:PRINT USING"###.#";F6

6940 F7=VAL(MID$(DL$(K),33,4))/10

6950 LOCATE 13,15,1:PRINT USING"###.#";F7

6960 F8=VAL(MID$(DL$(K),37,4))/10

6970 LOCATE 13,30,1:PRINT USING"###.#";F8

6980 F9=VAL(MID$(DL$(K),41,4))/10

6990 LOCATE 13,45,1:PRINT USING"###.#";F9

7000 F10=VAL(MID$(DL$(K),45,4))/10

7010 LOCATE 13,60,1:PRINT USING"###.#";F10

7020 F11=VAL(MID$(DL$(K),49,4))/10

7030 LOCATE 14,15,1:PRINT USING"###.#";F11

7040 F12=VAL(MID$(DL$(K),53,4))/10

7050 LOCATE 14,30,1:PRINT USING"###.#";F12

7060 F13=VAL(MID$(DL$(K),57,4))/10
Appendix E - Using Program VEGY

E-13

7070 LOCATE 14,45,1:PRINT USING"###.#";F13

7080 F14=VAL(MID$(DL$(K),61,4))/10

7090 LOCATE 14,60,1:PRINT USING"###.#";F14

7100 F15=VAL(MID$(DL$(K),65,2))

7110 LOCATE 16,14,1:PRINT USING"##";F15

7120 F16$=MID$(DL$(K),67,3)

7130 LOCATE 16,56,1:PRINT F16$

7140 F17=VAL(MID$(DL$(K),70,4))/100

7150 LOCATE 18,9,1:PRINT USING"##.##";F17

7160 F18=VAL(MID$(DL$(K),74,4))/100

7170 LOCATE 18,48,1:PRINT USING"##.##";F18

7180 F19=VAL(MID$(DL$(K),78,2))

7190 LOCATE 20,46,1:PRINT USING"##";F19

7200 COLOR 15,1

7210 RETURN

7220 '

7230 ' SUBROUTINE TO COMPUTE CWSI

7240 '

7250 DIM TEMP(8),X(100),Y(100),YC(100), QUAL$(3)

7260 QUAL$(1)="GOOD"

7270 QUAL$(2)="FAIR"

7280 QUAL$(3)="POOR" 

7290 OPEN "I",2,D$

7300 OPEN "O",3,"OUTPUT"

7310 E=2.7182818# 

7320 NO=0

7330 IPAGE=0 

7340 IF EOF(2) THEN 8750

7350 LINE INPUT#2,B$

7360 IDATE=VAL(MID$(B$,1,7))

7370 IHOUR=VAL(MID$(B$,9,4))

7380 ICROP=VAL(MID$(B$,13,2))

7390 IFIELD$=MID$(B$,15,10)

7400 TA=VAL(MID$(B$,25,4))/10

7410 TWB=VAL(MID$(B$,29,4))/10

7420 FOR I=1 TO 8

7430 M=33+(I-1)*4

7440 TEMP(I)=VAL(MID$(B$,M,4))/10

7450 NEXT I

7460 WINDS$=MID$(B$,65,2)

7470 WINDD$=MID$(B$,67,3)

7480 SLOPE=VAL(MID$(B$,70,4))/100

7490 OFFSET=VAL(MID$(B$,74,4))/100

7500 IQUAL=VAL(MID$(B$,78,2))

7510 '

7520 ' CHECK FOR BAD DATA

7530 ' 

7540 IF IQUAL=0 THEN 

7550 LPRINT " *****ERROR: BAD DATA QUALITY ON THE FOLLOWING RECORD. ";

7560 LPRINT "MUST BE 1, 2 OR 3"

7570 LPRINT DATE;IHOUR;ICROP;IFIELD$;TA;TWB;TEMP;WINDS$;WINDD$;SLOPE;OFFSET;IQUAL

7580 GOTO 7340

7590 END IF

7600 ' 

7610 ' CALCULATE MEAN TEMPERATURE OF PLANT 

7620 ' 

7630 TMPAVG=(TEMP(1)+TEMP(2)+TEMP(3)+TEMP(4)+TEMP(5)+TEMP(6)+TEMP(7)+TEMP(8))

7640 TMPAVG=TMPAVG/8!

7650 '

7660 ' CALCULATE TEMPERATURE DIFFERENTIAL

7670 ' TEMP DIFF = TEMP AVG. - DRY BULB TEMP.

7680 ' 

7690 TMPDIF = TMPAVG-TA

7700 ' 

7710 ' CALCULATE THE SATURATION VAPOR PRESSURE 
Appendix E - Using Program VEGY

E-14

7720 ' 

7730 XP=18.7209-(3806.41/(TA+273.16))-(222153!/(TA+273.16)^2)

7740 EO1=E^XP

7750 XP=18.7209-(3806.41/(TWB+273.16))-(222153!/(TWB+273.16)^2) 

7760 EO2=E^XP 

7770 EA=EO2-((.00066*(.00115*TWB+1!))*(980!*(TA-TWB)))

7780 VPD1=(EO1-EA)/10!

7790 IF (SLOPE=0! AND OFFSET=0!) THEN

7800 '

7810 ' DEVELOPING THE REGRESSION EQUATION. STORE VPD AND TC-TA VALUE

7820 ' 

7830 PRINT

7840 PRINT DL$(K)

7850 PRINT "Record skipped, no slope of offset provided."

7860 GOTO 7340 

7870 END IF

7880 '

7890 ' NOW CALCULATE THE UPPER LIMIT.

7900 ' 

7910 TC=TA+OFFSET

7920 XP=18.7209-(3806.41/(TC+273.16))-(222153!/(TC+273.16)^2) 

7930 VPD2=E^XP

7940 VPDIFF=(EO1-VPD2)/10!

7950 UPLMT=OFFSET+(SLOPE*VPDIFF) 

7960 ' 

7970 ' CALCULATE THE CROP WATER STRESS INDEX 

7980 ' 

7990 CWSI=(TMPDIF-(SLOPE*VPD1+OFFSET))/(UPLMT-(SLOPE*VPD1+OFFSET)) 

8000 ' 

8010 ' CALCULATE RELATIVE HUMIDITY 

8020 ' 

8030 RH=EA/EO1*100! 

8040 ' 

8050 ' ALL DONE WITH THIS SAMPLE. PRINT ANSWERS 

8060 ' 

8070 NO=NO+1 

8080 IF NO=0 GOTO 8290 '------LOOKS FOR BLANK DATE?

8090 '

8100 ' WRITE HEADINGS. 

8110 ' 

8120 IF NP=1 THEN 8130 ELSE 8230

8130 IPAGE= IPAGE + 1

8140 LPRINT CHR$(12);TAB(22);"CROP WATER STRESS INDEX COMPUTATIONS"

8150 D$=DATE$

8160 TODAY$=MID$(D$,1,2)+"/"+MID$(D$,4,2)+"/"+MID$(D$,9,2)

8170 LPRINT TAB(36);TODAY$

8180 LPRINT TAB(37);"Page ";IPAGE

8190 LPRINT

8200 LPRINT

8210 NP=2

8220 GOTO 8280

8230 LPRINT

8240 LPRINT TAB(30);"- - - - - - - - - -"

8250 LPRINT

8260 LPRINT

8270 NP=1

8280 NO=1

8290 LPRINT TAB(7);"SAMPLE";TAB(17);"SAMPLE"

8300 LPRINT TAB(8);"DATE";TAB(18);"TIME";TAB(28);"CROP";TAB(44);"FIELD"

8310 LPRINT TAB(7);"------";TAB(17);"------";TAB(28);"----";TAB(44);"-----"

8320 MO=INT(IDATE/10000)

8330 DY=INT(IDATE/100)-MO*100

8340 YR=IDATE-DY*100-MO*10000

8350 LPRINT USING" ##/##/## ######";MO,DY,YR,IHOUR;

8360 LPRINT USING" \ \ \ \";CROP$(ICROP),IFIELD$
Appendix E - Using Program VEGY

E-15

8370 LPRINT

8380 LPRINT " DRY BULB";TAB(13);"WET BULB";TAB(36);"SAMPLE TEMPERATURES";

8390 LPRINT TAB(75);"DATA"

8400 LPRINT TAB(5);"TEMP";TAB(15);"TEMP";

8410 LPRINT TAB(24);"(1) (2) (3) (4) (5) (6) (7) (8) WIND";

8420 LPRINT TAB(73);"QUALITY"

8430 LPRINT " --------";TAB(13);"--------";TAB(24);

8440 LPRINT "---- ---- ---- ---- ---- ---- ---- ---- ----";

8450 LPRINT TAB(73);"-------" 

8460 LPRINT USING" ##.# ##.# ";TA,TWB;

8470 LPRINT USING" ##.# ##.# ##.# ##.#";TEMP(1),TEMP(2),TEMP(3),TEMP(4);

8480 LPRINT USING" ##.# ##.# ##.# ##.#";TEMP(5),TEMP(6),TEMP(7),TEMP(8);

8490 LPRINT USING" \\ \ \ \ \";WINDS$,WINDD$,QUAL$(IQUAL)

8500 LPRINT

8510 LPRINT " SLOPE: ";

8520 LPRINT USING" #####.##";SLOPE

8530 LPRINT

8540 LPRINT " OFFSET: ";

8550 LPRINT USING" #####.##";OFFSET

8560 LPRINT

8570 LPRINT " TC-TA ";

8580 LPRINT USING" #####.## C";TMPDIF

8590 LPRINT

8600 LPRINT " VAPOR PRESSURE DEFICIT: ";

8610 LPRINT USING" #####.## KPA";VPD1

8620 LPRINT

8630 LPRINT " UPPER LIMIT: ";

8640 LPRINT USING" #####.## C";UPLMT

8650 LPRINT

8660 LPRINT " CROP WATER STRESS INDEX: ";

8670 LPRINT USING" #####.##";CWSI

8680 LPRINT

8690 LPRINT " RELATIVE HUMIDITY: ";

8700 LPRINT USING" #####.##%";RH

8710 GOTO 7340

8720 ' 

8730 ' END OF FILE.

8740 ' 

8750 RETURN

8760 '

8770 ' SUBROUTINE TO COMPUTE SLOPE AND OFFSET

8780 '

8790 E=2.7182818# 

8800 NO=0

8810 IPAGE=0 

8820 XCROP=0

8830 IF EOF(2) THEN 9250

8840 NO=NO+1

8850 LINE INPUT#2,B$

8860 ICROP=VAL(MID$(B$,13,2))

8870 'PRINT XCROP,ICROP

8880 IF XCROP=0 OR XCROP=ICROP THEN 8930

8890 LPRINT B$

8900 LPRINT "DATA SKIPPED, CROP NOT ";CROP$(XCROP)

8910 NO=NO-1

8920 GOTO 8830

8930 XCROP=ICROP

8940 TA=VAL(MID$(B$,25,4))/10

8950 TWB=VAL(MID$(B$,29,4))/10

8960 FOR I=1 TO 8

8970 M=33+(I-1)*4

8980 TEMP(I)=VAL(MID$(B$,M,4))/10

8990 NEXT I

9000 ' 

9010 ' CALCULATE MEAN TEMPERATURE OF PLANT 
Appendix E - Using Program VEGY

E-16

9020 ' 

9030 TMPAVG=(TEMP(1)+TEMP(2)+TEMP(3)+TEMP(4)+TEMP(5)+TEMP(6)+TEMP(7)+TEMP(8))

9040 TMPAVG=TMPAVG/8!

9050 '

9060 ' CALCULATE TEMPERATURE DIFFERENTIAL

9070 ' TEMP DIFF = TEMP AVG. - DRY BULB TEMP.

9080 ' 

9090 TMPDIF = TMPAVG-TA

9100 ' 

9110 ' CALCULATE THE SATURATION VAPOR PRESSURE 

9120 ' 

9130 XP=18.7209-(3806.41/(TA+273.16))-(222153!/(TA+273.16)^2)

9140 EO1=E^XP

9150 XP=18.7209-(3806.41/(TWB+273.16))-(222153!/(TWB+273.16)^2) 

9160 EO2=E^XP 

9170 EA=EO2-((.00066*(.00115*TWB+1!))*(980!*(TA-TWB)))

9180 VPD1=(EO1-EA)/10!

9190 X(NO)=VPD1 

9200 Y(NO)=TMPDIF 

9210 ISW=1 

9220 JCROP$=CROP$(ICROP) 

9230 GOTO 8830 

9240 ' CALCUALTE SLOPE AND OFFSET

9250 XSUM=0!

9260 X2SUM=0! 

9270 YSUM=0!

9280 XYSUM=0! 

9290 Y2SUM=0! 

9300 '

9310 ' SUM UP THE X VALUES 

9320 ' 

9330 FOR J=1 TO NO

9340 XSUM=XSUM+X(J)

9350 NEXT J

9360 '

9370 ' SUM UP X SQUARED VALUES 

9380 ' 

9390 FOR J=1 TO NO

9400 X2SUM=X2SUM + X(J)^2 

9410 NEXT J

9420 '

9430 ' SUM UP THE Y VALUES 

9440 ' 

9450 FOR J=1 TO NO

9460 YSUM=YSUM+Y(J)

9470 NEXT J

9480 '

9490 ' SUM THE PRODUCT OF X*Y

9500 ' 

9510 FOR J=1 TO NO

9520 XYSUM=XYSUM+(X(J)*Y(J)) 

9530 NEXT J

9540 '

9550 ' SUM UP THEE Y SQUARED VALUES

9560 ' 

9570 FOR J=1 TO NO

9580 Y2SUM=Y2SUM + Y(J)^2 

9590 NEXT J

9600 '

9610 ' DETERMINE THE ARITHMETIC MEAN FOR X AND Y 

9620 ' 

9630 XMEAN=XSUM/NO

9640 YMEAN=YSUM/NO

9650 '

9660 ' COMPUTE THE M(11),M(12), AND M(22) VALUES 
Appendix E - Using Program VEGY

E-17

9670 ' 

9680 M11=Y2SUM-(NO*(YMEAN)^2)

9690 M12=XYSUM-(NO*YMEAN*XMEAN) 

9700 M22=X2SUM-(NO*(XMEAN^2))

9710 '

9720 ' NOW THE 'B' AND 'A' VALUES

9730 ' 

9740 B=M12/M22 

9750 A=YMEAN-B*XMEAN 

9760 SLOPE=B 

9770 OFFSET=A

9780 ' 

9790 ' NOW CALCULATE THE R SQUARED VALUE AND WE ARE DONE.

9800 ' 

9810 SST=M11 

9820 SSR=ABS(B)^2*M22 

9830 R2=SSR/SST

9840 'IF ISW=0 THEN 6560 

9850 LPRINT CHR$(12);TAB(26);"SLOPE AND OFFSET CALCULATIONS"

9860 LPRINT

9870 LPRINT

9880 LPRINT USING" VPD AND TC-TA DATA PAIRS FOR WELL-WATERED \ 

\";CROP$(XCROP)

9890 LPRINT

9900 LPRINT TAB(21);"TC-TA TC-TA"

9910 LPRINT " POINT VPD (ACTUAL) (CALC)"

9920 LPRINT

9930 FOR J=1 TO NO

9940 YC(J)=SLOPE*X(J)+OFFSET 

9950 LPRINT USING" ### ####.# ####.# ####.# 

####.#";J,X(J),Y(J),YC(J)

9960 NEXT J

9970 LPRINT

9980 LPRINT USING" REGRESSION EQUATION: #####.## + #####.## X";OFFSET,SLOPE

9990 LPRINT USING" R SQUARED= ###.##";R2

10000 LPRINT CHR$(12)

10010 RETURN

10020 '

10030 ' SUBROUTINE TO PRINT DATA FILE

10040 '

10050 OPEN "O",1,D$

10060 FOR I=1 TO 50

10070 IF MID$(DL$(I),1,7)<=" " THEN 10100

10080 PRINT#1,DL$(I)

10090 NEXT I

10100 CLOSE

10110 RETURN

10120 '

10130 ' SUBROUTINE TO DISPLAY BAD DATA MESSAGE

10140 '

10150 COLOR 12,1

10160 LOCATE 22,1,1

10170 PRINT "BAD DATA, TRY AGAIN. "

10180 COLOR 15,1

10190 RETURN

10200 '

10201 ' SUBROUTINE TO SORT DATA BY FIELD NUMBER AND SAMPLING DATE

10202 '

10210 ' Build Sort Key

10220 '

10230 X2$ = ""

10231 'NR=K

10232 'LPRINT NR,CHR$(12)

10240 For L = 1 To NR

10242 X2$=MID$(DL$(L),15,10)
Appendix E - Using Program VEGY

E-18

10244 X2$=X2$+MID$(DL$(L),6,2)

10246 X2$=X2$+MID$(DL$(L),2,2)

10248 X2$=X2$+MID$(DL$(L),4,2)

10250 X2$=X2$+MID$(DL$(L),9,4)

10460 '

10470 ' Locate Record Position in File

10480 '

10490 If L = 1 Then

10500 RPointer(L) = L

10510 skey$(L) = X2$

10520 NumRec = L

10530 GoTo 11330 'loop3

10540 End If

10550 LL = 1

10560 UL = NumRec

10570 If X2$ < skey$(LL) Then

10580 'Print #F2, X2$; "<"; skey(LL), LL

10590 RN = 1

10600 GoTo 11150 'InsertRcd

10610 End If

10620 If X2$ = skey$(LL) Then

16030 'Print #F2, X2$; "="; skey(LL), LL

10640 RN = LL

10650 'Loop1:

10660 RN = RN + 1

16070 If RN > NumRec Then

16080 RN = NumRec

10690 GoTo 11290 'AppendRecord

10700 End If

10710 If X2$ = skey$(RN) Then

10720 GoTo 10650 'Loop1

10730 Else

10740 RN = RN - 1

10750 If RN <= 0 Then RN = 1

10760 GoTo 11150 'InsertRcd

10770 End If

10780 End If

10790 If X2$ > skey$(UL) Then

10800 'Print #F2, X2$; ">"; skey(UL), UL

10810 GoTo 11290 'AppendRecord

10820 End If

10830 If X2$ = skey$(UL) Then

10840 'Print #F2, X2$; "="; skey(UL), UL

10850 RN = UL

10860 'Loop2:

10870 RN = RN + 1

10880 If RN > NumRec Then

10890 RN = NumRec

10900 GoTo 11290 'AppendRecord

10910 End If

10920 If X2$ = skey$(RN) Then

10930 GoTo 10860 'Loop2

10940 Else

10950 ' RN = RN - 1

10960 If RN <= 0 Then RN = 1

10970 GoTo 11150 'InsertRcd

10980 End If

11000 End If

11010 'LBL4091:

11020 X = Int((UL + LL) / 2 + .5)

11030 'Print #F2, X2$, skey(X), X

11040 If X2$ > skey$(X) Then

11050 LL = X

11060 Else

11070 UL = X
Appendix E - Using Program VEGY

E-19

11080 End If

11090 'Print #F2, L, LL; X; UL, LLX$; X2$; ULX$

11100 If (UL - LL) = 1 Then

11110 RN = UL

11120 GoTo 11150 'InsertRcd

11130 End If

11140 GoTo 11010 'LBL4091

11150 'InsertRcd:

11160 For J = NumRec To RN Step -1

11170 If J <= 0 Then

11180 GoTo 11240 'Loop5

11190 End If

11200 'Print #F2, J, NumRec, RN

11210 skey$(J + 1) = skey$(J)

11220 RPointer(J + 1) = RPointer(J)

11230 Next J

11240 'Loop5:

11250 skey$(RN) = X2$

11260 RPointer(RN) = L

11270 NumRec = NumRec + 1

11280 GoTo 11330 'loop3

11290 'AppendRecord:

11300 NumRec = NumRec + 1

11310 skey$(NumRec) = X2$

11320 RPointer(NumRec) = L

11330 'loop3:

11340 '

11350 Next L

11560 'Close #F1

11370 ' All Records sorted, create new file.

11430 Open D$ For Output As 1

11440 'Open FILEIN$ For Random As F1 Len = RL

11450 For I = 1 To NR

11460 'Print #F3, rpointer(I)

11500 Print #1, DL$(RPOINTER(I))

11510 Next I

11520 Close

11580 RETURN
Index

Index-1

INDEX

Access tube

Accessibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

Driver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13, 23

location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 32

Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 37

Access tubes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13, 14, 18, 21, 23, 32

Acres . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2, 41

Adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C-1

Amount to apply ..................................................................... 6

Apparent Moisture Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Black body . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 21

Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18, 21, 22, 25, 26, 28

Consumptive Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 37

Crop . . . . . . . . . . . . . . . . . . . . . . . 1, 2, 4, 6, 8-10, 20-23, 30-37, 39, 41, E-1, E-2, E-5, E-6, E-12, E-14-17

Crop Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21, E-1

Crop stand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Crop water Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6, 9, 10, 20, 33-36, E-1, E-14, E-15

Crop Water Stress Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6, 9, 10, 33-36, E-1, E-14, E-15

CWSI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-10, 20, 30, 33, 35, 36, E-1, E-2, E-4, E-13-15

Data Sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22, 33

Plant foliage temperature data sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22, 33

Date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 6, 22, 29, 34-37, 40, 41, E-2, E-5, E-13-15, E-18

Dosimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

DR-503 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14, 15, 18, 26, 28, 35

Dry Barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19, 26-28

Dry-Bulb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20, 21, 36

Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 4, 6, 33, 37

Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Excess water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 34

Farm irrigation schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Farm number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Field data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33, C-2

Field Irrigation Scheduling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2, 4, 24, 35

Film badge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4, 13-15, 18, 19, 21, 24-28, 32, 33, 35, 37, C-1

Infrared thermometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10, 13, 19-21, 30, 33

Initialize the gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Irrigation Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12, 21, E-1, E-3, E-4

Neutron Moisture Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4, 13, 19, 24, 26, 27, C-1

Neutron Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii-5, 29

Next irrigation date . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 6

NRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24, 25

Nuclear Regulatory Commission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Plant foliage temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22, 33

Plant foliage temperature data sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22, 33

Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii-5, 14-19, 21, 23, 26, 28, 29, 37

Psychrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10, 20, 21, 30, 33

Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Refill Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 6, 10, 37

Refill point . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4, 10, 31-33, 35

Run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E-1

S-503 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14, 15, 26, 28, 35
Index

Index-2

Schedules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2, 37, 39

Scheduling irrigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1, 3, 4, 26, 31

Soil Moisture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4, 6, 8, 10, 15, 21, 25-27, 32-34

Soil Moisture depletion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Soil Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26, 31

Standard count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15, 18, 29

Standardization Barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Summary report sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Technicians . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24, 31, 37, 39

Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6, 8-11, 20-22, 30, 33, 36, A-1, A-5, E-2, E-14, E-16

Tube location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31, 32

Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21, 22, 26, 31, E-1

VEGY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33, 34, 7, E-1, E-2

Visible stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Water user . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Wet Barrel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19, 26, 28

Wet-bulb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8, 20, A-1, A-2, A-4, A-5