Former DPI irrigation officer at Deniliquin, Lindsay Evans, recently retired says now’s the time to plan which crops to irrigate.

As the availability of water for the next irrigation season remains uncertain, irrigators should now be carefully planning which crops to irrigate if there is an allocation announcement, according to former DPI irrigation officer at Deniliquin, Lindsay Evans, recently retired.

By late winter, irrigators in the northern inland river systems should have a fair idea of water availability, however, those in the Riverina may have to wait until mid spring to find out if and what their allocation will be, he said.

"Often the returns per megalitre (ML) from the supplementary irrigation of winter crops are superior to those of summer crops, but it remains to be seen if allocation announcements are made in time to make it worthwhile irrigating winter crops," he said.

"Decisions on spring irrigations will also depend on whether the crop is established on time, how well it has grown during the winter, its stage of growth when irrigation water becomes available and its yield prospects.

"Commodity prices and the competing need to produce feed for livestock are other considerations."

According to DPI’s irrigated crop gross margins (on the website www.dpi.nsw.gov.au under ‘Farm budgets and costs’), spring irrigations of some of the pulse crops can give high returns per ML applied, provided surface layouts and soils are suitable, or if overhead irrigation is possible.

"Wheat will usually give a better and more consistent return per ML than the other winter cereals and canola," he said.

"Wheat should be irrigated before head emergence and soon after flowering to maximise the response from the water.

"When barley prices are attractive, one irrigation well before head emergence is the best option, but if prices are likely to be low or if more than a single irrigation is needed, it is better to use the water on wheat."

Experience in the irrigation districts of the Riverina indicates that only one early spring irrigation of canola is likely to give a worthwhile response, provided the crop was sown and emerged on time.

Daytime temperatures over 29 degrees C are a greater limitation on canola yields than soil water.

If water allocation announcements are too late for winter crop watering, irrigators will have to decide if they intend on planting a summer crop.

If so, they will then have to predict what volume is likely to be available, and how much water can or should be purchased for a summer crop program, Lindsay said.

Cotton is likely to be the main option in the north of the state, and rice in the south. However, in all inland irrigation districts, maize for grain or silage, soybeans and forage crops for summer livestock feed may be considered.

Decisions on what summer crop to grow will depend more on location (mainly climate and soils), layouts, machinery needs, prices and marketing arrangements, as opposed to the relative profitability of the crops.

Whatever the crop chosen, it is essential sufficient water is or will become available to provide it with adequate water through to harvest.

"It is better to fully irrigate a smaller area of summer crop than to under irrigate or run short on a large area. For this reason a decision on the area to be sown cannot be made until the allocation announcement just prior to the intended time of sowing," he said.

"Select the most fertile fields, and if possible those closest to the pump site or wheel to minimise channel loses, and conduct pump and channel maintenance well before the season starts."

Contact your local irrigation officer or district agronomist for management and options advice, see www.dpi.nsw.gov.au