12/12/2016

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Reddy, Krishna

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2014

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Water Availability and Water

Management (211)
Agricultural System
Competitiveness and Sustainability|
(216)

Project : USDA ARS.

S62@9800

Research Project: Development of Sustainable Production Systems and Water Management
Technology for the Mid South

Location: Crop Production Systems Research

2014 Annual Report

1a. Objectives (from AD-416):
Develop cropping systems, conservation management practices and crop rotations with improved water management and
enhanced economic and environmental sustainability.

1b. Approach (from AD-416):

Improved irrigation scheduling and application technologies and water management tools will be developed and delivered to
producers to improve water use and crop yield and quality. The research will develop production systems and identify
management practices that improve soil quality and increase profitability by incorporating conservation production practices,
alternative crops and crop rotations. Profitability of management practices and production systems will be tested with economic
analysis. Fundamental principles of successful production systems will be delineated, and examined for impacts on risks,
competitiveness and environmental impacts.

3. Progress Report:

‘Acorn study under controlled environment to determine at which growth stages of corn plants irrigation water can be reduced
without affecting yield was completed. Corn plants were treated with 100%, 75% and 50% of field capacity in a silt loam soil at
different growth stages starting two weeks before flowering. The results showed that cutting down water to 75% after the milk
stage did not affect yield. With additional tests, this information can help producers save money by reducing irrigation water at
those growth stages in com. Significant progress was made in the implementation and testing of water management tools. The
new Mississippi Irrigation Scheduling Tool (MIST) was tested and validated for common corn and soybean production practices
and soil types in Mississippi in research and production fields. Watermark soil water sensors were installed at six inch (15 cm)
increments to a depth of three feet (0.91 m), and soil water measurements downloaded weekly. Plant growth measurements
were taken weekly, and used to develop single crop coefficients as outlined in established procedures. Dual crop coefficients
are being explored as a possible method of accounting for variability of alluvial soils. Soil water measurements and plant growth
measurements were compared to evapotranspiration calculations made with the Modified Penman-Monteith in the MIST
program to adjust crop coefficients to better reflect actual crop water use in the soils and environment of the Delta. Water release
curves for typical Mississippi soils were developed and soil moisture sensors calibrated to known water contents. Soils textural
analysis is used to adjust recommended irrigation levels based on soil water holding capacity. Note that most soils are silt and
loam; no soils that were analyzed were true clay soils. Analyzed soils will have approximately 1.2-2.5 inches of plant available
water per foot of soil. Soil cores were taken from production and research fields, and bulk density, soil nutrient and soil hydraulic
properties determined. Weather data were downloaded from all weather stations reported by the Delta Research and Extension
Center Weather Center, Natural Resources Conservation Service (NRCS), Soil Climate Analysis Network (SCAN) weather
systems were analyzed for completeness and accuracy. The impact of planting date and irrigation on soybean yield were
determined. Early planted soybeans yielded higher, but were more susceptible to lack of adequate water. Two primary crop
parameters can be used for tracking crop growth: plant height and interception of sunlight. Results show that light interception is
more appropriate for tracking crop growth as a single curve can be used for most planting dates. Plant height differs with planting
date. The overall magnitude of crop height is most likely cultivar dependent. However, later planting increases the rate of crop
growth, altering the initial stage of the crop height growth curve. The uniform resource locator for the web site server is now open
Scientists have begun writing summaries and eductional materials for the water management website. The information can be
viewed at: hppti/www.agwater.msucare.com. The irrigation scheduler has been implemented into the user interface, and the
interface is being tested.

4. Accomplishments

1. Efficient water use in cor production. Due to uncertainty in the amount and timing of precipitation during the cropping season,
producers in the Mississippi Delta are heavily depending on supplemental irrigation. This has become costly to the producers,
because of increase in energy prices, and itis also depleting the underground water. Developing methods to use water timely
and efficiently can cut down irrigation costs and conserve the underground water. Scientists at the USDA-ARS, Crop Production
Systems Research Unit in Stoneville, MS, conducted a study under controlled environment to determine at which growth stages
of com plants irrigation water can be reduced without affecting yield. Corn plants were treated with 100%, 75% and 50% of field
capacity in a silt loam soil at different growth stages starting two weeks before flowering. The results showed that cutting down
water to 75% after the milk stage did not affect yield. With additional tests, this information can help producers save money by
reducing irrigation water at those growth stages in corn.

Last Modified: 2/23/2016)

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