Weekly information to assist irrigators in matching water delivery with plant water requirements will be published this spring and summer in Country News.
In an arrangement with Agriculture Victoria and Murray Dairy, weekly evapotranspiration figures will be published on page two of Country News.
The figures were published last irrigation season and some irrigators reported the information was useful in planning irrigation delivery.
Rob O’Connor, from Agriculture Victoria’s Echuca office, said the information was about helping irrigators better match irrigations with plant water requirements to maximise plant growth and water efficiency
‘‘Basically the information will help irrigators avoid green droughts — where plants are green but growth rates and water efficiency are not as good,’’ Mr O’Connor said.
‘‘The irrigation requirements are based on evapotranspiration (ETo), which is a calculation of plant water use, using various elements of the weather including sunshine, temperature, wind and humidity
‘‘Typically spring and autumn are difficult times of the year for farmers to get irrigation right, due to more variable weather conditions.
‘‘The info in the summary is likely to be of value this time of year.
‘‘The summary will provide irrigation scheduling information for farmers who use either surface (flood) irrigation or sprinkler systems.’’
Mr O’Connor said most farmers already had a pretty good feel of when to irrigate.
‘‘A lot of irrigators use the summary to refine what they are already doing.
‘‘For rye-grass based pasture, research has shown growth is optimised when cumulative ETo minus rainfall equals 40mm to 50mm, starting from when surface water has drained away following the last irrigation,’’ he said.
‘‘Over 300 local irrigators and service providers currently receive a more detailed weekly ETo email update.
‘‘This season we have developed a fairly simple surface irrigation spreadsheet tool that will come out with the email.
‘‘Irrigators will be able to plug a few of their details in to the spreadsheet including their last irrigation date, and the spreadsheet will visually show when the next irrigation is due.’’
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■Evapotranspiration is the water used by plants at their optimum growth rate, plus any loss of water from the soil surface. Evapotranspiration depends on a number of factors including sunlight, wind, temperature and humidity.