Patchy rain cuts nitrogen use

Claire TyrrellCountryman

Nitrogen applications are down in the northern agricultural region as patchy rainfall prompts growers to be conservative.

Mullewa farmers John and Mark Flannagan are taking a cautious approach with nitrogen inputs because they have not had enough rain to support high applications.

"We've had 135mm for the year so far," John said.

"We've only had 7.5mm in July, which is not enough. If we had 25 to 30mm out of this rain we would have put more urea out.

"The weather patterns are not conducive to rain, with the high pressure systems."

John, who farms with brother Mark on 9000 hectares east of Mullewa, said time was running out for crops to take advantage of applied nutrients.

"The northern region usually starts tapering off in August, so if we don't get more rain by the end of July we will be getting a bit nervous," he said.

The Flannagans put down one application of urea - with 30 units of nitrogen - at 60kg per hectare at seeding time.

John said that they would usually go back and apply more nitrogen but the "window was closing" for this to happen.

The brothers also reduced their cropping program to 6300ha this year due to the lack of rain.

"We budgeted on 7000ha but we got a bit nervous with the lack of rain," he said.

"We had 60mm at the start of May and so we were seeding wet right up until the end of May.

"If it rained the first week of June we would have done a bit more but we finished at the end of May."

John said he put enough nitrogen out to obtain average yields of about 1.5 tonnes per hectare on his wheat, provided they received adequate rainfall.

"The way things are looking, we would be happy with 1.3t/ha," he said.The Flannagans had one of their best seasons last year, averaging 2.5t for their wheat. Their long-term average is close to 1.4t/ha.

John said there was little residual nitrogen in the soil from last year but that would not change his approach this season.

CSBP Mingenew-Irwin area manager Luigi Moreschi said nitrogen sales were down compared to this time last year.

"Yield expectations are very different at the moment compared with this time last year because of the late start and the lack of rain in July," he said.

"In this area, I think 3-3.3t/ha (on wheat) would be the highest we would be looking at.

"June sales were down by about a third. Some of those were losses and some were growers deferring until July."

Mr Moreschi said there was a lot of uncertainty around fertiliser applications but warned growers not to be too pessimistic.

"Most guys are tentative but I think a lot of them will still get 250 to 300mm of rainfall for the year," he said.

"People have to be careful they don't get too pessimistic. They have to understand the soil types, look at how much rain they've had and how much they are likely to get.

"From there they can make some judgments and see if their nitrogen levels cover an average to below average finish."

Summit Fertilizers recently released trial data from its Mingenew site last year.

Summit northern region manager Eddy Pol said the trials showed that growers should top-dress crops with nitrogen within six to eight weeks after emergence.

He advised growers to review their nitrogen rates in light of current conditions and expected yield potential.

"Growers should keep in mind that for every 100kg/ha increase in wheat or barley, their crop will need an additional 4 to 5kg/ha of nitrogen."

Mr Pol said compound and liquid nitrogen fertilisers had a similar effect on crops.

Trials in the region are continuing.

Fast facts *

Who: John and Mark Flannagan

Where: Mullewa

What: 5000ha wheat, 1300ha canola

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