System and method for optimizing evapotranspiration based irrigation control using a moisture sensor

1. An irrigation method comprising:

(a) a controller acquiring data regarding soil moisture from one or more soil moisture sensors disposed in an irrigation area, wherein the controller adjusts evapotranspiration (ET) data based on the soil moisture data;

(b) the controller determining whether to irrigate or withhold irrigation from the irrigation area based on a combination of the ET data and the soil moisture data acquired in step (a); and

(c) an irrigation means responsive to the controller determining whether to apply or withhold irrigation from the irrigation area in step (b) for respectively applying or withholding irrigation from the irrigation area,

wherein step (b) includes the controller solving the following equation EQ1:

ETm

=

ETc

-

α

*

(

VSM

-

VSMnom

)

*

ETc

(

VSMmax

-

VSMmin

)

*

1

/

2

where ETm=moisture-corrected ET;

ETc=rain-corrected ET, and ETc=ET for a predetermined interval or period of time+Rainfall amount received for the predetermined interval or period of time;

VSM=actual volumetric soil moisture, wherein the actual volumetric soil moisture is determined based on the data regarding soil moisture from the one or more soil moisture sensors;

VSMmax=moisture of the soil in the irrigation area when said soil is at or near field capacity;

VSMmin=moisture of the soil in the irrigation area when said soil is at or near wilting point;

VSMnom=nominal or ideal volumetric soil moisture; and

α=user-definable regulation variable between 0 and 1: 0=no regulation,

1=full regulation.

2. The method of claim 1 , wherein the ET data of step (b) is acquired from a memory of the controller, is determined by the controller, or is acquired from a source remote from the controller.

3. The method of claim 2 , wherein the source remote from the computer is a server that is in communication with the controller.

4. The method of claim 3 , wherein the server is in communication with the controller via a communication network.

5. The method of claim 3 , wherein the communication network is comprised of a wired and/or wireless local area network, a wired and/or wireless wide area network, a combination of a wired and/or wireless local area network and a wired and/or wireless wide area network, or a cellular network.

6. The method of claim 3 , wherein the communication network is comprised of the Internet.

7. The method of claim 1 , wherein step (c) is performed daily or multiple times daily.

8. The method of claim 1 , wherein ET is determined from one or more of the following obtained from one or more weather stations or one or more historical records: air temperature; solar radiation; air humidity; and wind speed.

9. The method of claim 1 , wherein VSM is determined from the data regarding soil moisture acquired from a plurality of soil moisture sensors.

10. The method of claim 1 , wherein the predetermined interval or period of time is a day or a portion thereof.

11. The method of claim 1 , wherein in response to determining to apply irrigation, the controller causes the irrigation means to apply an amount of irrigation that is substantially equal to ET or ETm minus the rainfall amount received for the predetermined interval or period of time.

12. The method of claim 1 , wherein the controller includes a processor operating under the control of a control program that causes the controller to solve EQ1 based on the value of VSM determined from the acquired data regarding soil moisture, a value of ET and a rainfall amount.

13. The method of claim 1 , wherein the controller acquires the rainfall amount either via a computer network or via at least one rainfall sensor.

14. The method of claim 1 , wherein the controller automatically adjusts a future ET-based irrigation schedule based on the soil moisture data.

15. An irrigation system comprising:

a controller operating under the control of a control program;

irrigation means responsive to the controller for applying or withholding moisture from an irrigation area; and

one or more soil moisture sensors for sensing soil moisture in the irrigation area and for outputting data regarding said sensed soil moisture, wherein, under the control of the control program, the controller is operative for acquiring the data regarding the sensed soil moisture output by the one or more soil moisture sensors, for adjusting evapotranspiration (ET) data based on the acquired soil moisture data, for determining whether to irrigate or withhold irrigation from the irrigation area based on a combination of the ET data and the acquired soil moisture data, and for causing the irrigation means to apply irrigation to the irrigation area upon determining to irrigate the irrigation area,

wherein the controller determines whether to irrigate or withhold irrigation from the irrigation area by solving the following equation EQ1:

ETm

=

ETc

-

α

*

(

V

⁢

⁢

S

⁢

⁢

M

-

V

⁢

⁢

S

⁢

⁢

M

⁢

⁢

nom

)

*

ETc

(

V

⁢

⁢

S

⁢

⁢

M

⁢

⁢

max

-

V

⁢

⁢

S

⁢

⁢

M

⁢

⁢

min

)

*

1/2

where ETm=moisture-corrected ET;

ETc=rain-corrected ET, and ETc=ET for a predetermined interval or period of time+Rainfall amount received for the predetermined interval or period of time;

VSM=actual volumetric soil moisture, wherein the actual volumetric soil moisture is determined based on the data regarding soil moisture from the one or more soil moisture sensors;

VSMmax=moisture of the soil in the irrigation area when said soil is at or near field capacity;

VSMmin=moisture of the soil in the irrigation area when said soil is at or near wilting point;

VSMnom=nominal or ideal volumetric soil moisture; and

α=user-definable regulation variable between 0 and 1: 0=no regulation,

1=full regulation.

16. The irrigation system of claim 15 , further including at least one rainfall sensor operative for outputting data regarding an amount of rainfall, wherein the controller determines whether to irrigate or withhold irrigation from the irrigation area based on the data regarding the amount of rainfall.

17. The irrigation system of claim 15 , wherein the ET data is programmed into a memory of the controller, is determined by the controller, in real-time based on weather station data, or is acquired electronically by the controller via a communication network.

18. An irrigation method comprising:

(a) a controller acquiring data regarding soil moisture from one or more soil moisture sensors disposed in an irrigation area;

(b) the controller determining whether to irrigate or withhold irrigation from the irrigation area based on a combination of evapotranspiration (ET) data and the soil moisture data acquired in step (a); and

(c) an irrigation means responsive to the controller determining whether to apply or withhold irrigation from the irrigation area in step (b) for respectively applying or withholding irrigation from the irrigation area,

wherein step (b) includes the controller solving the following equation EQ1;

ETm

=

ETc

-

α

*

(

V

⁢

⁢

S

⁢

⁢

M

-

V

⁢

⁢

S

⁢

⁢

M

⁢

⁢

nom

)

*

ETc

(

V

⁢

⁢

S

⁢

⁢

M

⁢

⁢

max

-

V

⁢

⁢

S

⁢

⁢

M

⁢

⁢

min

)

*

1/2

where ETm=moisture-corrected ET;

ETc=rain-corrected ET, and ETc=ET for a predetermined interval or period of time+Rainfall amount received for the predetermined interval or period of time;

VSM=actual volumetric soil moisture, wherein the actual volumetric soil moisture is determined based on the data regarding soil moisture from the one or more soil moisture sensors;

VSMmax=moisture of the soil in the irrigation area when said soil is at or near field capacity;

VSMmin=moisture of the soil in the irrigation area when said soil is at or near wilting point;

VSMnom=nominal or ideal volumetric soil moisture; and

α=user-definable regulation variable between 0 and 1: 0=no regulation,

1=full regulation.