Abstract:
A method and system for monitoring the dynamic response of soil moisture and setting a threshold in relation to the field capacity of a soil area is disclosed herein. By measuring the dynamic response of soil moisture under wet soil conditions, one can determine a practical field capacity for the soil, in-situ, based solely on the soil moisture sensor output. Essentially, by looking at how the soil moisture level varies with time one can determine the field capacity.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The Present Application claims priority to U.S. Provisional Patent Application No. 61/553,165, filed on Oct. 29, 2011, and U.S. Provisional Patent Application No. 61/553,238 filed on Oct. 30, 2011, and the present application is a continuation-in-part application of U.S. patent application Ser. No. 13/017,538, filed on Jan. 31, 2011, which claims priority to U.S. Provisional Patent Application No. 61/300,028, filed on Feb. 1, 2010, all of which are hereby incorporated by reference in their entireties. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is relates to an irrigation system. More specifically, the present invention relates to an irrigation system designed to reduce water usage. 
     2. Description of the Related Art 
     The prior art discusses other irrigation systems and methods. 
     In attempting to efficiently apply irrigation water, a critical problem is setting watering thresholds to an appropriate level that achieves two goals—minimizing water usage, and maintaining plant health. In general, it has been found that these two goals can be met by setting the water target to a percentage of the field capacity (generally 70% to 80%). In order to determine the field capacity (moisture content of a particular soil at which water freely drains under gravity) one can take a soil sample for every type of soil where a soil moisture sensor is installed. This process is time consuming, expensive, and in practice, not particularly accurate. 
     The Present Invention seeks to resolve the problems of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a method for automatic irrigation threshold setting. The method includes measuring a dynamic response of soil moisture of a soil area under a fully saturated environment and setting a threshold for the soil area based on the measurements of the dynamic response. 
     One aspect of the present invention utilizes a smart irrigation controller, which is coupled to a set of sensors. The smart controller controls irrigation and monitors dynamic moisture responses. The controller monitors an increase in soil moisture in response to a period of time of active irrigation in order to determine irrigation efficiency, as well as to determine runoff and run times required to account for soil moisture deficits during irrigation events. The controller also derives at least one of a set of soil/landscape properties, which includes field capacity, water infiltration rates, presence of thick organic surface areas (thatch); and produces at least one recommendation for management practices comprising aeration, thatch removal, soil amendment; and detects at least one of several irrigation system deficiencies, such as broken sprinkler heads, drip lines, and poor spatial coverage. 
     Monitoring the dynamic response of soil moisture is preferably over a predetermined time period. 
     The soil area is preferably a residential lawn. Optionally, the soil area is a golf course, a farm, a football field, all irrigated recreational surfaces, agricultural operations, gardens, landfill caps, or other land areas being restored to plant covering. 
     Another aspect of the present invention is a threshold setting that is 70% to 80% of the field capacity of the soil area. The threshold is capable of changing to a percentage of field capacity that may be dependent upon additional factors, such as, time to next scheduled event, or available irrigation water, plant type, slope, etc. 
     Yet another aspect of the present invention is a threshold setting that is set to optimize water efficiency, plant growth and plant health, to minimize runoff, and to minimize contamination to groundwater. 
     Yet another aspect of the present invention is a method whereby all adaptive algorithm operations are consistent with watering restrictions that are imposed by regulatory authorities or imposed by the end user to prohibit watering during certain times. 
     Yet another aspect of the present invention is a method that relies on external data provided by a communication capability to modify irrigation practices to reflect at least one of local emergencies, current weather making irrigation inefficient such as high winds or temperatures, or other factors. 
     By measuring the dynamic response of soil moisture under wet soil conditions, one can determine a practical field capacity for the soil, in-situ, based solely on the soil moisture sensor output. Essentially, by looking at how the soil moisture level varies with time one can determine the field capacity. When the soil is wetted above field capacity, its moisture content will fall fairly quickly initially to a point where field capacity is reached. After this point, moisture levels will continue to decrease but at a much slower rate reflecting evapotranspiration from the soil. By using sensor data, an uC, and appropriate algorithms, one can develop procedures for automatically setting determining field capacity and setting thresholds. In residential, agriculture, or in sports/turf markets the present invention sets this as either a “set threshold” mode or a continuously adapting mode adaptive. 
     In a set threshold mode, shortly after installing the sensors, we would put our central irrigation controller into a set threshold mode. We would then fully saturate the soil around the sensors either manually or through turning on irrigation. We would then monitor the dynamic response of soil moisture over some period of time (probably around a few hours to a few days) and determine field capacity. These values would then be used to set the thresholds. 
     In an adaptive mode, the system would continuously be monitoring the dynamic response of soil moisture and determining, based on either irrigation events or rainfall, the field capacity. This would be allowed to change over time (with some characteristic time constant—probably on the order of ten days) to reflect changes in root mass, organic content, and soil compaction. 
     One aspect of the present invention is or more soil moisture sensors in communication (wireless, wired, or otherwise) with a uC based “decision element. 
     Another aspect of the present invention is decision element with, or without, the capability to control/schedule irrigation over areas in which the communicating sensors are installed. 
     Yet another aspect of the present invention is uC based algorithms that interpret soil moisture data and automatically produce measurements of field capacity or other appropriate measures of a soils response to irrigation. 
     Yet another aspect of the present invention is in systems that allow the decision element to control irrigation, the irrigation would be automatically set based on the determined field capacity. 
     Having briefly described the present invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a top perspective view of a wireless soil sensor of the present invention with a sleeve attached over a portion of the wireless soil sensor. 
         FIG. 2  is a first side view of the wireless soil sensor of  FIG. 1 . 
         FIG. 3  is an opposing side view of the wireless soil sensor of  FIG. 1 . 
         FIG. 4  is top plan view of the wireless soil sensor of  FIG. 1 . 
         FIG. 5  is a top perspective view of a wireless soil sensor of the present invention without a sleeve attached over a portion of the wireless soil sensor. 
         FIG. 6  is a first side view of the wireless soil sensor of  FIG. 5 . 
         FIG. 7  is top plan view of the wireless soil sensor of  FIG. 5 . 
         FIG. 8  is a rear plan view of the wireless soil sensor of  FIG. 5 . 
         FIG. 9  is a front view of an interrupter with a front panel open. 
         FIG. 10  is a front view of an interrupter with a door closed. 
         FIG. 11  is a top perspective view of an interrupter with a front panel open to illustrate an interface. 
         FIG. 12  is a top perspective view of an interrupter with a front panel closed. 
         FIG. 13  is an isolated view of an interface of an interrupter. 
         FIG. 14  is a flow chart of a general method of an end-to-end system of the present invention. 
         FIG. 15  is a schematic diagram of a prior art irrigation control system. 
         FIG. 16  is a schematic diagram of an irrigation control system with an irrigation interrupt. 
         FIG. 17  is a schematic diagram of an irrigation control system with a wireless irrigation controller. 
         FIG. 18  is a schematic diagram of a prior art irrigation control system. 
         FIG. 19  is a schematic diagram of an irrigation control system with a tethered sensor. 
         FIG. 20  is a schematic diagram of an irrigation control system with a wireless interrupt. 
         FIG. 21  is a schematic diagram of an irrigation control system with a wireless controller. 
         FIG. 22  is a block diagram of a preferred embodiment of an irrigation interrupter. 
         FIG. 23  a schematic diagram of an irrigation system employing an interrupter of the present invention. 
         FIG. 24  a schematic diagram of an irrigation system employing an interrupter of the present invention. 
         FIG. 25  is a block diagram of a preferred embodiment of a wireless sub-surface soil sensor. 
         FIG. 26  is a graph. 
         FIG. 27  is a graph. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention may be used with a system and method such as disclosed in Glancy et al., U.S. patent application Ser. No. 12/983,241, filed on Dec. 31, 2010 for an Apparatus And Method For Wireless Real Time Measurement And Control Of Soil And Turf Conditions, which is hereby incorporated by reference in its entirety. 
     The present invention may be used with a system, sensor and method such as disclosed in Campbell, U.S. Pat. No. 7,482,820 for a Sensor For Measuring Moisture And Salinity, which is hereby incorporated by reference in its entirety. 
     The present invention may use a chemical sensor probe such as disclose in U.S. Pat. No. 4,059,499 which is hereby incorporated by reference in its entirety. 
     The present invention may use a chemical sensor probe such as disclose in U.S. Pat. No. 5,033,397 which is hereby incorporated by reference in its entirety. 
     The present invention may utilize the systems and methods disclosed in Magro et al., U.S. patent application Ser. No. 12/697,226, filed on Jan. 30, 2010, for a Method And System For Monitoring Soil And Water Resources, which is hereby incorporated by reference in its entirety. 
     The present invention may also utilize the systems and methods disclosed in Magro et al., U.S. patent application Ser. No. 12/911,720, filed on Oct. 25, 2010 for a Method For Soil Analysis, which is hereby incorporated by reference in its entirety. 
     Magro et al., U.S. patent application Ser. No. 12/698,176, filed on Feb. 2, 2010 for a Method And System For Monitoring Soil And Water Resources is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/698,138, filed on Feb. 1, 2010 for a Method, System And Sensor For Performing Soil Measurements is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. Pat. No. 8,035,403 for a Wireless Soil Sensor Utilizing A RF Frequency For Performing Soil Moisture Measurements is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/697,258, filed on Jan. 31, 2010 for a Method And System For Improving A Communication Range And Reliability Of A Soil Sensor Antenna is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/697,264, filed on Jan. 31, 2010 for an Antenna Circuit Matching The Soil Conditions is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/697,283, filed on Jan. 31, 2010 for an Adaptive Irrigation Control is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/697,281, filed on Jan. 31, 2010 for an Irrigation Interrupter is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/697,292, filed on Jan. 31, 2010 for a Wireless Soil Sensor Utilizing A RF Frequency For Performing Soil Moisture Measurements is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/697,256, filed on Jan. 31, 2010 for a Method And System For Soil And Water Resources is hereby incorporated by reference in its entirety. 
     Campbell et al., U.S. patent application Ser. No. 12/697,257, filed on Jan. 31, 2010 for a Method And System For Soil And Water Resources is hereby incorporated by reference in its entirety. 
     Systems, methods, sensors, controllers and interrupters for optimizing irrigation are disclosed in Campbell et al., U.S. patent application Ser. No. 12/697,258, filed on Jan. 31, 2010, for a Method And System For Improving A Communication Range And Reliability Of A Soil Sensor Antenna, which is hereby incorporated by reference in its entirety. 
     Likewise, systems, methods, sensors, controllers and interrupters for optimizing irrigation are disclosed in Campbell et al., U.S. patent application Ser. No. 12/697,254, filed on Jan. 31, 2010, for a Method And System For Soil And Water Resources, which is hereby incorporated by reference in its entirety. 
     Magro et al., U.S. patent application Ser. No. 13/017,538, filed on Jan. 31, 2011 for an Automatic Efficient Irrigation Threshold Setting is hereby incorporated by reference in its entirety. 
     A wireless soil sensor  21  is shown in  FIGS. 1-8 . The wireless soil sensor is placed in the soil below the surface to monitor various parameters of the soil such as moisture. Other parameters include salinity and temperature. 
     A wireless interrupter  12  is shown in  FIGS. 9-12  and an interface  12  for the wireless interrupter  12  is shown in  FIG. 13 . The wireless interrupter  12  has a main body  12   a  and a front panel  12   b  which allows for viewing of the interface  12   c.    
     As shown in  FIGS. 23 and 24 , an irrigation system employing an interrupter  12  is generally designated  20 . The system  20  preferably includes a plurality of wireless sub-surface sensors  21  (upper soil  21   a  and lower soil  21   b ), a plurality of above-ground receivers  22 , an interrupter  12  located at an operations center, and a plurality of above-ground sensors  24 . The above ground sensors  24  preferably measures air temperature, wind speed, and relative humidity. 
       FIG. 22  illustrates a block diagram of the preferred components of an interrupter  12 . The interrupter  12  preferably has a housing  70 , a microcontroller  71 , a radiofrequency antenna  72 , a memory  79 , a display  73  and a power supply  74 . 
       FIG. 25  illustrates a wireless sub-surface sensor  21  alternatively utilized in the system  20 . The wireless sub-surface sensor  21  preferably has a housing  30 , a processor  31  with an integrated sensor  33 , a configuration switchable antenna  32 , and a power supply  34 . 
     A schematic diagram of a prior art irrigation control system is shown in  FIG. 15 . 
     A wireless device (soil sensor  21 , interrupter  12  or controller  11 ) typically goes through a network entry process, in which it searches for and locks onto the signals of other members of the wireless network it is entering. After the signal lock, a handshake takes place, where the entering node transmits and expects to receive a sequence of well defined messages over the air. At the conclusion of this handshake, the entering node is considered a member of the network. It will be able to transmit and receive over the air messages using a well defined protocol. It will be considered a “Joined” member. A “joined” member may maintain a connection oriented or a connection less link with its radio neighbors. (Example of a connection oriented link is a time synchronized CDMA channel between a station and a cell tower. Example of a connection-less link is the Carrier Sense Medium Access (CSMA) link between a WiFi station and its Access Point). 
     Typically, if the “joined” member is not able to communicate with the other end of the link within a predefined window, it loses its “joined” status, and has to go through a network entry process again. At the least, it may have to perform a less complex re-synchronization task to re-establish its time synch with the network (if is uses a connection oriented link). The link establishment, re-synch, or network entry process will continue (typically with less and less frequency, upon failed attempts) until a) the node rejoins the network, b) the time interval between reentry attempts becomes so large that the node effectively becomes dormant, or c) until the node runs out of battery. 
     The wireless soil sensor  21  is required to transmit messages for all of the above transactions. If the cause of loss of “joined” status is dues to surrounding soil that is too moist or too saline then the rejoin attempts will also fail. If this condition is not detected, the wireless soil sensor  21  will continue wasting scarce battery reserves for transmissions. The adaptive transmission scheduling mechanism discussed here takes into account the moisture and conductivity of the soil that surrounds the wireless soil sensor  21 . It will stop transmissions until the moisture levels of the soil surrounding the node have dropped to manageable levels that will allow successful transmissions. 
     An example of a preferred method of adaptive transmission for wireless soil sensor  21  is as follows. A preferred method for an adaptive transmission aspect of the present invention begins with determining if (x) number of consecutive connection attempts (or transmission) have failed. Next, the method includes determining if the measured moisture level (or a composite metric that includes moisture and conductivity levels) is at some threshold (y) or above. Next, the method includes assuming the surrounding soil is too wet. Next, the method includes suspending the timers that control the transmission activity of the node. Next, the method includes, continuing to sample the moisture levels, and as long as the moisture levels are above threshold (z), attempting to connect once every predetermined time period, T (T time units only, where T is larger than typical inter-transmission intervals). Next, the method includes determining when the moisture levels have dropped below a threshold (w), then un-suspending the timers and a state machine that controls transmissions. Next, the method includes, allowing the normal protocol to resume for the system. 
     One can manage what one can measure. And, one can do it all on a real time basis. Soil intelligence equals savings and health. The present invention is preferably a complete package of advanced software, agronomic services and wireless sensor system that helps take the guesswork out of turf management. A flow chart of an overall method is shown in  FIG. 14 . On aspect of the present invention turns raw data into useful operating thresholds which help maintain and optimize plant health and performance. One aspect of the present invention provides the necessary formula that automatically alerts when and where a facility might be experiencing stress and what the treatment options are. 
     One aspect of the present invention has a data collection component of the software, which allows for monitoring in real time, from an office or from on-site or remote locations, the key variables of moisture, salinity and temperature from each sensor site. The graphic displays are user-friendly and the present invention helps set high-low threshold ranges for each sensor location so that one instantly knows whether the soil is in or out of the optimal range for growth conditions and playability. By continuously analyzing the recorded data and thresholds for each location, this component visually alerts one to conditions at each sensor location and suggests what actions are needed to be more efficient and effective. 
     One aspect of the present invention optimizes turf and crop health and playability by measuring root zone moisture, salinity and temperature and applying best practices to your turf management. Once the wireless soil sensors  21  are in the ground sending raw data, an optimal zone is devised by analyzing accumulated sensor data, putting decades of agronomic experience to use and applying tested scientific principles. The Zone defines the upper and lower operating thresholds to ensure plant health. This helps with: course evaluation; soil and water analyses; review of existing practices including irrigation, nutritional inputs and maintenance; threshold determinations; sensor placement and more. On a real-time basis, one can manage greens, tees, fairways and rough to keep a facility in prime condition. 
     The wireless soil sensor  21  provides wireless interface between the sensing elements and the Communication Control Nodes (CCNs) that preferably form a mesh network. The key features include the shape: 8×4 inches. Buried with a Standard Cup Cutter. Supports sensors: analog or digital. 3 “D” Cell batteries: 4+ years life, field replaceable. 1 Watt FHSS radio board supports approximately 400 ft. range 4 in. in ground. Sensor interface and antenna for over air programming for product upgrades. 
     The key functionalities of the wireless soil sensor  21  are as follows: provide accurate, real-time data on soil moisture, temperature and salinity. Key Features: Pre calibrated for sand, silt and clay. Moisture measurement. Accuracy: +/−0.02WFV from 0 to saturation at &lt;2.5 dS/m conductivity. +/−0.04WFV from 0 to saturation at 2.5-5 dS/m conductivity. Repeatability: +/−0.001WFV. WFV is the fraction of soil occupied by water, a soil at 10% soil moisture has a WFV of 0.10. Conductivity measurement: Accuracy: +/−2% or 0.02 dS/m, whichever is greater, 0-2.5 dS/m. +/−5%, 2.5-5 dS/m. Repeatability: +/−1% or 0.01 dS/m whichever is greater, 0-2.5 dS/m. +/−4%, 2.5-5 dS/m. Temperature measurement: Accuracy: +/−0.5° C. from −10 to +50° C., +/−1° F. from 14 to 122° F. Repeatability: 0.05° C., 0.1° F. Benefits: Dual sensors allow gradients of soil moisture, conductivity, and temperature to be monitored. High accuracy and repeatability. No individual sensor calibration required. 
     Above-Ground Wireless Mesh Network: Communication Control Nodes. Key Functionality: CCNs are the interface to the Sensor Nodes. Each is a radio node that automatically joins and forms the mesh network on power up. Key Features: Range of ˜1 mile above ground unobstructed. Requires 1 Amp while transmitting. 12-24 Volt AC or DC power. Can be attached via 110/220 Volt power adapter. Weather proof enclosure. Benefits: Self forming, self healing, multihop mesh network; No special wiring required; Two way communications with link quality statistics; Control of buried nodes; The multihop mesh allows extension of the wireless coverage area far beyond the nominal range of the radios. 
     Agronomy is the study of plant and soil sciences and how they impact crop and plant production, performance and yield. Every plant has specific tolerances to environmental variables like moisture, temperature and salinity which impact the ability to grow, flourish, proliferate and perform to expectations. Just as a doctor can help monitor and advise to keep a person in peak physical condition, agronomists can help keep your facility in peak condition. Agronomists using the present invention help define those optimal threshold levels as well as their impacts on root, leaf and lateral growth, responses to man-made or natural environmental stress, and resistance to disease and insect pressure. As a result, in this case water usage was reduced by nearly 30% while playability was enhanced uniformly. The indicator of the present invention predicts the likelihood for disease outbreaks before they happen. 
     The software package utilized feeds off data provided by the wireless soil sensors  21  and wireless communications system. It displays real time conditions and provides comprehensive intelligence and predictive actions. The system helps establish health- and performance-optimizing operating threshold ranges, evaluate your data and current practices, and refine existing programs. The results, optimal turf conditions and real savings, will generate a strong and lasting return on investment. The agronomic benefits include more efficient salinity management, uniform irrigation, deeper rooting, predictive disease control and healthier, more stable conditions. There are environmental benefits as well like water conservation, reduced use of phosphates, nitrates and pesticides, a reduced carbon/water footprint and regulatory compliance. 
     Real time sensor measurements can include soil oxygen, pH, concentrations of specific ion species—(Na+ has a very detrimental effect compared to the same concentration of Ca+2). Pollutant measurements include both hydrocarbons (oils, gasoline, etc.) and metals (chromium, lead, etc.). 
     As to the wireless transmission network, an alternative process of an adaptive model may be utilized with the present invention. An antenna, designed for efficient RF communication in air is relatively straightforward because the key electrical properties of the transmission medium (air) are well known and essentially constant. In below ground RF transmission, the key properties of the soils will very greatly with moisture content and salinity hence it is a much more difficult problem to design an efficient antenna. In addition, the best antenna design is influenced by how deeply buried the antenna is. The present invention includes elements to the antenna circuit that, under control of microcontroller, allow for varying the properties of the antenna to more closely match the conditions and improve range and reliability of communication. The sensor of the present invention measures both the dielectric constant of the soil (moisture) and conductivity (salinity) directly. Hence, the sensor measures precisely the two most important factors affecting antenna efficiency. 
     In a predictive model, the method includes activating a sensor and measuring soil electrical properties. The method also includes, based on the soil properties, activating antenna elements to give an effective transmission. The method also includes transmitting sensor data. 
     In an adaptive model, the method includes activating a sensor and measuring soil electrical properties. The method also includes transmitting data repeatedly until all switchable antenna configurations have been attempted. The method also includes monitoring signal strength for each transmission. The method also includes repeat this process possibly every 60 sensor transmissions. 
     As time progress, a receiver can put together a two dimensional map (soil dielectric constant on one axis, soil conductivity on the other) with received power for all antenna configurations. The map is downloaded on some regular schedule to the buried sensor node. When the sensor makes a measurement, the sensor reviews the map for the antenna configuration that gives the highest receive power at the receiver for the current conditions. A node configures an antenna and sends a packet of data. Even after the map is downloaded, every 60 sensor readings will have all the different antenna configurations attempted which will allow the map evolve. 
     The advantage of this adaptive process is that it can make an allowance for the actual depth of burial as well as the relative antenna locations and orientations. This is important because different antenna configurations have different radiation patterns. Hence, it is possible that a less than ideal antenna configuration works best in that it has the highest radiated power in the particular direction and polarization that the receiver antenna lies in. 
     As shown in  FIG. 15 , an irrigation system  10 ′ includes a 24VAC power supply, a controller  11 , and a valve box  13  with valves  123   a  and  13   b . These irrigation systems  10 ′ work by using a 24 volt alternating current source to open valves  13   a  and  13   b . When no current flows (open switch  51 ), the valves  13   a  and  13   b  are closed and no water flows. A controller/timer  11  is used to turn on the current to the separate valves  13   a  and  13   b . Usually there is a “common” wire  53  that returns the current from all valves  13   a  and  13   b . Separate “hot” wires  52   a  and  52   b  are used for each of the valves  13   a  and  13   b . As shown in  FIG. 18 , the irrigation controller  11  controls the valve box  13  through wires  17   a  and  17   b  to provide water form source pipe  16   b  to sprinkler pipe  16   a  for dispersion on a soil  15  through sprinkler  14 . 
     As shown in  FIG. 19 , the prior art is improved upon by a system  10  with a tethered sensor  21 ′ in which is a sensor coupled to an interrupter  12  wired into the wiring  17   a ,  17   b ,  17   c  and  17   d  of the valve box  13 . The interrupter  12  acts to turn off a scheduled irrigation if the moisture exceeds a predetermined threshold established by a user. The interrupter  12  acts as an in-line switch that closes (allowing current to flow and the valve  13  to open) only if the controller  11  starts a scheduled irrigation and the soil moisture is below a predetermined threshold established by a user). In the system  10  of  FIG. 19 , the interrupter  12  can only interrupt a scheduled irrigation, not initiate an irrigation. The system  10  has a sensor  21  which is cabled (no wireless communication). The system  10  of  FIG. 19  has the advantage of being very simple, it is capable of being easily installed into virtually all existing irrigation systems, and it requires no independent power (the system  10  draws power off the 24VAC irrigation line). 
     As shown in  FIG. 20 , a wireless interrupt approach is similar to the “Tethered Sensor” system  10  of  FIG. 19 , except that wireless communication is used between a wireless soil sensor  21  and an interrupter  12 . The wireless soil sensor  21  requires battery power and the interrupter  12  requires a battery to accommodate flexible wireless reporting. The principle advantage of the system  10  of  FIG. 20  is that no cabling is needed, and installation is simpler than the tethered system  10  of  FIG. 19 . As shown in  FIG. 20 , the wireless soil sensor  21  transmits a wireless signal  18   a  to the interrupter  12  pertaining to the moisture levels of the soil in a particular soil area. 
     A wireless controller system  10  is shown in  FIG. 21 . The wireless controller system  10  uses a wireless link back to a wireless irrigation controller  11  (there is no “interrupter”) The principle advantage of the wireless controller system  10  of  FIG. 21  is that the wireless soil sensors  21  preferably initiate irrigation if needed (allowing for the user to set scheduled irrigation times as well if desired). A user also may allow the wireless controller  11  to look at more than one wireless soil sensor  21  for each irrigation zone (area irrigated by one valve  13 ) taking an average, use the lowest value, etc. One can also allow for simpler level adjusting, including such features as a “hot day” button nudging the target water levels up a notch and many others. 
     The goal of one aspect of the present invention is to develop an inexpensive and easy to install system compatible with existing irrigation systems that can be quickly configured by homeowners/landscapers of limited technical sophistication. An objective of the present invention is an overall lower cost, a system that is easy to install in existing and new irrigation systems, setup that is as easy to use as a traditional irrigation controller, and careful design of setup features, default modes, user input device and display to give a superior customer interface. 
     Irrigation interrupt of the system interfaces simply with existing irrigation control systems to over-ride scheduled irrigation when moisture levels hit user settable thresholds. When operating in this manner, the system is incapable of initiating an irrigation event and needs to be used with a conventional irrigation controller. An irrigation controller  11  of the system  10  can initiate and stop irrigation events and replaces existing installation irrigation controllers or is suitable for complete control of new installations through both timing of irrigation to certain times of the day as well as based on near real-time soil moisture data. 
     As mentioned above, a typical irrigation controller system  10 ′ is shown in  FIG. 15 . The system  10 ′ includes a 24VAC power supply connected to 120VAC and an irrigation controller  11 . Wiring  52   a  and  52   b  leads from the controller  11  to one or more valve boxes  13 . When the current loop is closed, the valves  13   a  and  13   b  open and a zone is watered. Typically, the controller  11  is set to turn on and off valves at predetermined times for a set time. 
     In the irrigation interrupt system  10 , as shown in  FIG. 16 , the interrupter  12  is positioned between the standard irrigation controller  11  and the valves  13   a  and  13   b . A wireless soil sensor  21  is placed in each irrigation zone and the wireless soil sensor  21  is in periodic communication with the irrigation controller  12 . In this system, watering only occurs when both the standard irrigation controller  11  indicates that it is time to water and the irrigation interrupter  12  indicates that soil moisture is below a predetermined threshold. The interrupter  12  opens switch  54   a  and  54   b  to terminate the current flow through lines  52   a ′ and  52   b ′ and close the valves  13   a  and  13   b . Line  55  provides power to the interrupter  12 , especially when the switch  51  of the controller  11  is open. 
     In the wireless irrigation controller system  10  of  FIG. 17 , the same interrupter hardware is used but the inputs to the irrigation interrupter  12  are always on, i.e. the irrigation interrupt  12  is now in control and irrigation will occur under the direct control of the wireless interrupter  12  based on soil moisture data. Different firmware is necessary, but the hardware is identical with only minimal changes in the wiring. 
     In both systems, power for the irrigation interrupter  12  is drawn directly off the 24VAC eliminating the need for a separate power supply. 
     The system  10  is capable of operating with soil moisture only wireless soil sensors  21  with integrated two-way wireless telemetry, sensor firmware, an irrigation interrupter/controller (Controller) and controller firmware. The wireless soil sensors consist of a soil moisture only sensor, wireless two-way telemetry, microcontroller, and at least some non-volatile memory, and are preferably battery powered. These components are integrated into one physical package (no cabling) and the wireless soil sensor  21  is buried in strategic locations to monitor soil moisture conditions. The sensor firmware manages making sensor measurements, transmitting them to the controller, receiving controller commands, and power-management (putting system to sleep). The controller  11  preferably consists of two-way wireless telemetry compatible with the wireless soil sensors  21 , a microcontroller, non-volatile memory, a user input (preferably a four or five way wheel), display (preferably 36 character two line LCD), and circuitry for opening or closing switches for irrigation zones (switch in an open position is over-riding irrigation). In existing irrigation systems and for use with an already installed controller, the wireless controller  11  is spliced into existing wiring close to an existing irrigation controller. In replacing an existing irrigation controller or in new installations, the wireless controller  11  is directly connected to irrigation zone wiring. The controller firmware allows collection of wireless telemetry of soil moisture data, “commissioning” of new wireless soil sensors  21 , i.e. associating a wireless soil sensor  21  with an irrigation zone and an installation, setting irrigation thresholds, etc. 
     All of the components preferably operate over a temperature range of −20 to 70° C. (with the exception of the display which is operable over 0 to 50° C.) and are capable of storage over −20 to 70° C. All components preferably are Human Body Model ESD resistant but not lightning resistant. Wireless soil sensors  21  are preferably fully waterproof while the interrupters  12  preferably only have a low level of “splashproofing”. For the purposes of determining battery shelf life in the wireless soil sensors  21 , a temperature under 40 C is assumed (temperature, depending on battery technology, can greatly impact self discharge rates). 
     Wireless telemetry range of approximately 100-200 feet is preferred. The range is achieved at depths of up to 12 inches and in moderate clutter (vegetation, slight topography, through garage wall, etc.). A wireless soil sensor  21  is preferably installed at least as close as 3 inches from soil surface for monitoring soil moisture in shallow rooting turf. The package of the wireless soil sensor is preferably no larger than 2″×2″×8″ (ideally 1.5″×1.5″×6″). A bulky package is difficult to install (particularly at shallow depths), disrupt soil environment, and a turn-off to consumers. A non-volatile memory is preferred. Timekeeping is accurate to within +/−2% which allows the wireless soil sensors  21  to wakeup at on a regular schedule, timing for I2C commands, as well as scheduling sensor “listen” windows for wireless receive modes. 
     The wireless soil sensor  21  is capable of receiving simple operational parameters wirelessly from a controller  11  or an interrupter  12 , which allows the controller  11  or the interrupter  12  to set reporting interval, selection of adaptive algorithms, etc. 
     A procedure for re-programming the wireless soil sensors  21  after production is included in order to allow for changes encountered in debugging or upgrades. Alternatively, it can be through a programming header in the battery or by some other wireless programming option. 
     The wireless soil sensor  21  is preferably able to detect imminent battery, to prevent the wireless soil sensors  21  from failing suddenly with no warning or begin to operate intermittently reflecting battery temperature and other variable as well as possibly giving corrupted data that may result in incorrect irrigation decisions. 
     The sensor firmware is capable of executing and reading I2C commands. Analog sensor requires I2C commands to control oscillator and make A/D measurements. I2C commands need to be executed sequentially according to a sloppy timing of about +/−3 mS over 100 mS. I2C can operate anywhere from 20 to 200 KHz. The sensor firmware is able to perform simple calculations like conversion of raw A/D values into soil moisture which requires simple functions-addition, subtraction, division, polynomials but no log, trig, etc. functions. The sensor firmware is capable of going into a very low power mode between set measurement interval with routines to wake up at end of interval which may range from 1-100 min. which is set in a non-volatile configuration file which can be modified by interrupt controller. After measurement is complete, soil moisture data needs to be sent to interrupt controller  11 . 
     The sensor firmware preferably has a static soil moisture mode. An operational mode that allows the wireless soil sensor  21  to wake up, measure soil moisture, and if a change in soil moisture from the last wirelessly reported measurement does not exceed a settable threshold, return to a sleep mode without sending data. This threshold value, as well as whether this feature is enabled, preferably resides in a non-volatile configuration file which can be modified by the interrupt controller  11 . The wireless soil sensor  21  preferably transmits a new reading once every six hours regardless of soil moisture changes to confirm operation. 
     The wireless soil sensor  21  preferably has a default mode firmware upon power restart for the sensor firmware, which allows a wireless soil sensor  21  to be commissioned, i.e. assigned to a specific irrigation interrupter to allow for resolving sensors from a close neighbors residence. In addition, commissioning must be flexible to allow for a change in assigned interrupt controller  11  in the future or if commissioning is lost. 
     A wireless soil sensor  21  is preferably capable of a listening mode in a power efficient manner for receiving changes to the configuration file wirelessly from the interrupt controller  11  with a maximum file size of 100 bytes at least once a month without degrading three year sensor battery life. The wireless soil sensor  21  preferably has the ability to download full operating firmware. 
     On a regular schedule (about once every six hours) the wireless soil sensor  21  preferably provides in addition to the soil moisture value, diagnostics such as battery voltage, and raw measured values not to exceed an additional 25 bytes. This data is used to assess performance and for diagnosis of bugs or sensor failure. 
     If the raw A/D values used to determine soil moisture data are out of normal ranges, the wireless soil sensor  21  preferably sends a “Bad Data” even if the computed soil moisture value appears reasonable. This helps detect failed wireless soil sensors  21  and prevent bad control actions. 
     The irrigation interrupter  12  is capable of turning on and off AC current up to 700 mA continuously at 70 C for each irrigation zone from an AC voltage range of 16 to 34 volts with no more that 1V in drop across switching circuitry. Switching circuitry is not damaged by inductive transients generated by the turn off of valve solenoids. 
     Regardless of whether the interrupt controller  11  is allowing or blocking irrigation, the interrupt controller  11  can detect the presence of an AC voltage (generated by irrigation controller  11  to initiate an irrigation). This feature allows for calculations of savings such as % of scheduled irrigation events that were canceled by system. 
     The hardware for the irrigation interrupter  12  is preferably resistant to moderate ESD and transients that may enter system through 24 VAC transformer in order to be reliable. 
     The interrupt controller  11  draws power directly from nominal 24VAC transformer to avoid having to use a separate power supply with a maximum current draw of 100 mA. The interrupt controller  11  operates correctly with an AC input varying from 16 to 34 VAC to account for AC mains voltage of 84 to 130 VAC (typical specified level of AC power seen in a household) and variation in transformer output with load. 
     The interrupt controller  11  is capable of operating in typical residential systems which have between four and eight zones. More sophisticated systems could be addressed by using multiple units. 
     The interrupt controller  11  is preferably capable of a log for the last 30 days of soil moisture readings for eight zones at 10 minute interval as well as whether an irrigation event is occurring, and whether it has been interrupted at 1 minute intervals in non-volatile memory. The log is preferably structured so accurate date and time is available for data record. This feature is good for both debugging purposes but also in allowing the system to display to the user the amount of water saved thus justifying the product. 
     Firmware responds as gracefully as possible to problems. For instance, if soil moisture data is out of range or uC lockup (possibly detected by watchdog circuit) irrigation proceeds according to the irrigation controller  11  (i.e. no interrupt). If an irrigation interrupter  12  is operating as a wireless irrigation controller (no standard irrigation controller), the system  10  should default to no irrigation. Failure modes give obvious indication of problems. 
     Ample code space is preferably reserved to allow for extensive additional features in the future. All user settable configurations are preferably stored in non-volatile memory so as to allow for seamless recovery from lockup or loss of power. Preferably, a real time clock has the ability to keep time after power loss for up to 1 month. 
     The interrupter firmware is capable of generating a user water savings report for the last day, week, and month (i.e. percent of scheduled irrigation that was interrupted) by zone and as a whole for all eight zones as well as total run time per zone. 
     A process is developed to allow sensors upon installation or system expansion to be assigned to a particular irrigation zone for a particular irrigation interrupter. The process needs to be flexible enough to allow for replacement of failed wireless soil sensors  21  as well. This allows the system  10  to be used with neighboring installations without confusion as well as assigning the right sensor to the right zone. 
     A user sets, for each zone, the maximum soil moisture level that will terminate an irrigation event. There is also a settable hysteresis, Y, i.e. if during a single scheduled irrigation event the soil moisture rises about the threshold X and irrigation is stopped, it would not begin again until level fell to X-Y. This prevents valves from turning on and off rapidly when approaching the threshold. When new irrigation event occurs, the threshold defaults back to X. 
     A hold feature allows a user to hold current conditions going forward (i.e. take last soil moisture readings and apply as thresholds). 
     A show current status mode for the interrupt controller  11  defaults to when no keypad entry has occurred for a minute or so and shows zone by zone-threshold, last soil moisture data, irrigation is being attempted, and if irrigation is being interrupted. 
     The save configuration allows up to six configurations to be saved, named, and recalled (for all zones thresholds, hysteresis, adaptive algorithms on or off, etc.). This allows for summer and winter settings, etc. 
     A disable setting is where all zones are enabled and the system is under control of the irrigation controller  11  solely, i.e the interrupter  12  allows valves  13   a  and  13   b  to be on at all times when the standard irrigation controller  11  schedules irrigation regardless of the soil moisture data. This is a “safety mode” so that if there are critical problems, the user is not forced to reconfigure things to keep the grass from dying. 
     A bump feature allows a user to “bump” up or down all thresholds equally at an approximately 0.5% water by volume increment (allows for quick adjustment for hot weather or other reasons), which revert to previous settings after 1 days unless user selects to apply them permanently. 
     The firmware is preferably capable of detecting missing or out of range soil moisture and low battery conditions and display warning. 
     A wireless irrigation controller mode allows the irrigation interrupter  12  to function as full soil moisture data driven irrigation controller  11  without the use of a standard irrigation controller  11 . Essentially all of the features of a standard irrigation controller  11  are implemented such as scheduling irrigation times, valve run-times, etc. These scheduled events are subjected to the same “interrupt” schemes as the irrigation interrupter  12  based on soil moisture data. 
     When water is applied to the soil the wireless soil sensors  21  report the increase in moisture content but also look at the tail off in moisture levels when irrigation ceases. In cases of significant overwatering, there is a sharp spike in moisture levels followed by a sharp fall after irrigation ceases. This is due to the soil essentially being so wet it “free drains” below the root zone (thus wasting the water). The present invention implements algorithms to monitor this and adjust irrigation events to eliminate this wasteful practice allowing the system to essentially configure itself over time. The wireless soil sensor  21  is preferably directly integrated with a radio and microcontroller. It also preferably has a sleeve that fits over the sensor that the user removes to turn it on. It also preferably has an optional microcontroller generated clock signal to avoid having to use a separate oscillator for the conductivity measurement. It also preferably has the same RF frequency the radio uses to eliminate having to use a separate oscillator for the soil moisture measurement. It also preferably uses “spread spectrum oscillators” to achieve FCC compliance. It also preferably has sensor components that are currently PCB may be made out of conducting plastic formulations simplifying assembly, improving aesthetics, and reducing costs. 
     In  FIG. 26 , the soil moisture value shows three peaks corresponding to irrigation events. The initial big spike up was caused by dumping water on the sensor install site shortly after installation (this was done intentionally). It shows a number of classic features of rapid run-up in soil moisture following irrigation, a quick fall as water rapidly percolates to depth (most likely due to exceeding field capacity). A scaled soil moisture gradient (it is essentially the derivative of soil moisture as a function of time—the slope of the curve) is also shown. It is scaled to fit on the same graph and the signs are switched so that a positive value reflects a declining soil moisture. All of the negative values (rising soil moisture) are suppressed as they are not useful in the proposed scheme. 
     In  FIG. 27 , the soil moisture gradient is plotted as a function of soil moisture. 
     The theoretical basis of this approach is that the higher the soil moisture value, the greater the hydraulic conductivity is. Hydraulic conductivity measures how fast a gradient in the soil moisture is removed by moisture flowing from the wet to dry areas. Hydraulic conductivity is highly soil dependent and can increase by orders of magnitude from dry to wet. When field capacity is reached, hydraulic conductivity becomes very high (flow rate is then limited by the ability of water to flow to depth and is high for a sand and much lower in a clay). 
     This is roughly borne out in the graph above. The data clusters below the line called the static threshold are at about a SM gradient of 3. Of importance is that the resolution in the saved moisture data (0.1%) results in a SM gradient of 0.5 (this is an approximate noise floor in that rounding errors could cause a value of 0.5). In addition, if a moderate 0.3″ of ET is occurring over a 10 hour period in a soil with turf roots to 6″ we would expect a SM gradient (caused by the turf extracting water of about 1. Obviously, in some cases the ET will be higher and may occur over a shorter time, water will be preferentially extracted near our sensor depth, etc. Hence, a limit of 3 is set as a soil moisture gradient under relatively static conditions where moisture isn&#39;t percolating below the root zone. The idea is that the intersection point shown in the graph represents a point where we should expect little percolation of soil moisture below the root zone. 
     It is important to make sure the data entering the algorithm is free of anomalies (wild soil moisture values caused by corrupted packets), missing data points, data right after the irrigation event ends, etc. 
     Calculation of First Derivative is a simple process of subtracting data points to get rate of change. Negative values (wetting events) are rejected. 
     Lumping all soil moisture gradient values for particular windows (0-1%, 1-2%, . . . 69-70% soil moisture) allows application of adaptive algorithms that allow for water thresholds to adapt over time as new data comes available (for example, keep 90% of old value, 10% of most recent value giving the possibility of a slow drift with time). It will also allow for noise reduction by schemes such as tossing out the values above or below one standard deviation from the bucket average. 
     Curve Fitting/Statistical Analysis determines “Static Threshold” or assumes a value, and fits data points above static threshold and determine intercept point. This would be the upper end of the irrigation target. 
     From the foregoing it is believed that those skilled in the pertinent art will recognize the meritorious advancement of this invention and will readily understand that while the present invention has been described in association with a preferred embodiment thereof, and other embodiments illustrated in the accompanying drawings, numerous changes modification and substitutions of equivalents may be made therein without departing from the spirit and scope of this invention which is intended to be unlimited by the foregoing except as may appear in the following appended claim. Therefore, the embodiments of the invention in which an exclusive property or privilege is claimed are defined in the following appended claims.