Irrigation controller

A method for controlling irrigation, comprising the steps of:

• measuring temperature data at a certain site;
• calculating solely from the measured temperature data and extraterrestrial radiation influenced equivalent evaporation data relating to the certain site a reference evapotranspiration value indicative of an estimation of the current watering needs of a certain reference vegetation at that certain site;
• adjusting the reference evapotranspiration value to account for both a user specified local adjustment factor and a type of vegetation at the site, wherein the local adjustment factor accounts for noted regionalization inaccuracies in the solely temperature/radiation calculated reference evapotranspiration value, to calculate a net evapotranspiration value indicative of an estimation of the current watering needs of the type of vegetation at that certain site;
• determining a watering program for the certain site;
• and
• implementing the determined watering program to have the processing unit issue commands for controlling the actuation of irrigation control valves at the site to replace lost water.

An irrigation control apparatus, comprising:

• an evapotranspiration module operating to calculate solely from measured temperature data at a certain site and extraterrestrial radiation influenced equivalent evaporation data for the certain site a reference evapotranspiration value indicative of an estimation of the current watering needs of a certain reference vegetation at the certain site;
• an irrigation controller operating to issue commands for controlling the actuation of irrigation control valves at the certain site in accordance with a watering program, the irrigation controller further operating to request at each instance of an irrigation event the reference evapotranspiration value from the evapotranspiration module and process the received reference evapotranspiration value to:
• adjust the reference evapotranspiration value to account for both a user specified local adjustment factor and a type of vegetation at the certain site, wherein the local adjustment factor accounts for noted regionalization inaccuracies in the solely temperature/radiation calculated reference evapotranspiration value, to calculate a net evapotranspiration value indicative of an estimation of the current watering needs of the type of vegetation at that certain site;
• determine a watering program for the certain site;
• and
• implement the determined watering program to have the processing unit issue commands for controlling the actuation of irrigation control valves at the site to replace lost water.

An evapotranspiration module for connection to an irrigation controller, comprising:

• a communications port supporting bus communications with the irrigation controller;
• a processing unit operating to calculate solely from measured temperature data at a certain site and extraterrestrial radiation influenced equivalent evaporation data for that certain site a reference evapotranspiration value indicative of an estimation of the current watering needs of a certain reference vegetation at the certain site;
• and
• means responsive to a first bus communication received at the communications port from the irrigation controller which requests reference evapotranspiration value information for sending in a second bus communication output from the communications port to the irrigation controller the processing unit calculated reference evapotranspiration value.