System and method for irrigation control

1. A controller for controlling an irrigation schedule in an irrigation system, the irrigation system including a plurality of sprinkler heads connected via a plurality of conduits to a water source, the controller comprising:

a database that includes information relating to historical evapo-transpiration rates for a plurality of sectors located within a geographical area, the information including the historical period-average evapotranspiration rate for each period of the year per sector, and the maximum period-average evapotranspiration rate that occurs in one year per sector;

an input means for permitting a user to enter irrigation parameters into the controller, wherein the parameters include:

a Maximum Irrigation Duration;

an identifier for identifying the sector in which the irrigation system is located; and

the current date; and

a microprocessor configured to divide, for each sector, the historical period-average evapotranspiration rate for each period of the year by the maximum period-average evapotranspiration rate to provide a Period Reduction Factor for each sector, and being further configured to adjust the Maximum Irrigation Duration that has been entered into the controller by multiplying the Maximum Irrigation Duration by the Period Reduction Factor for the current period associated with the sector that has been identified by the user, to obtain an Actual Irrigation Duration for the current period for the identified sector, the microprocessor being further configured to cause the irrigation system to irrigate for the Actual Irrigation Duration during the current period.

2. The controller of claim 1 , wherein the sector identifier is a zip code.

3. The controller of claim 1 , wherein the sector identifier is a county name.

4. The controller of claim 1 , wherein the sector identifier is a city name.

5. The controller of claim 1 , wherein the microprocessor is configured to sequentially recalculate the Actual Irrigation Duration in each new period by applying the Period Reduction Factor associated with each new period, and causing the irrigation system to irrigate for the Actual Irrigation Duration during the new current period.

6. The controller of claim 1 , wherein the period associated with the Period Reduction Factor is a month.

7. The controller of claim 1 , wherein the period associated with the Period Reduction Factor is a week.

8. The controller of claim 1 , wherein the period associated with the Period Reduction Factor is a day.

9. A method of controlling the duration of irrigation by an irrigation system that includes a plurality of sprinkler heads connected via a plurality of conduits to a water source, the method comprising:

compiling a database that includes information relating to historical evapo-transpiration rates for a plurality of sectors located within a geographical area;

entering irrigation parameters into the controller, wherein the parameters include:

a Maximum Irrigation Duration;

an identifier for identifying the sector in which the irrigation system is situated; and

the current date;

deriving, from the information, Period Reduction Factors applicable over a year for a sector identified by a user, wherein the Period Reduction Factors are derived as the historical period-average evapotranspiration rate for each period of the year, divided by the maximum period-average evapotranspiration rate that occurs in a year for the identified sector;

adjusting the Maximum Irrigation Duration by multiplying the Maximum Irrigation Duration by a Period Reduction Factor for the current period, to obtain an Actual Irrigation Duration for the current period for the identified sector; and

causing the irrigation system to irrigate for the Actual Irrigation Duration during the current period.

10. The method of claim 9 , wherein entering a sector identifier into the controller includes entering a zip code.

11. The method of claim 9 , wherein entering a sector identifier into the controller includes entering a county name.

12. The method of claim 9 , wherein entering a sector identifier into the controller includes entering a city name.

13. The method of claim 9 , wherein the period associated with the Period Reduction Factor is one month.

14. The method of claim 9 , wherein the period associated with the Period Reduction Factor is one week.

15. The method of claim 9 , wherein the period associated with the Period Reduction Factor is one day.

16. The method of claim 9 , wherein adjusting the Maximum Irrigation Duration includes sequentially recalculating the Actual Irrigation Duration in each new period by applying the Period Reduction Factor associated with each new period, and causing the irrigation system to irrigate for the Actual Irrigation Duration during the new current period.