Grain growers across the wheatbelt have been urged to monitor their crops for nitrogen deficiency, as they face a different soil nitrogen scenario this year compared with recent seasons.
Last season’s high grain yields and the dry summer have combined to reduce soil nitrogen and may result in some crops running short of nitrogen this year.
Department of Agriculture and Food research officer Craig Scanlan said with a drier than normal winter and spring forecast, growers would be wise to monitor the nitrogen status of their crops.
Dr Scanlan said there were several tools available to assist growers to make informed decisions about their nitrogen regime for the rest of the season.
“Tissue testing is an effective way to assess whether the soil supply of nitrogen is keeping up with crop demand, though the weather conditions prior to taking the tissue sample needs to be taken into account,” he said.
There are several commercial and online applications available to assist growers, while most fertiliser companies have their own recommendation models.
Growers can also access valuable information from local Yield Prophet® sites, which is supported by DAFWA.
“Yield Prophet® is probably the best model we have for dealing with unusual seasons, because it uses daily rainfall and temperatures to model wheat growth for different nitrogen scenarios,” Dr Scanlan said.
“There’s also an app called N-Broadacre, based on DAFWA’s Select Your Nitrogen model, which can help to gauge potential yield responses to N.”
Data from the widespread Farm Focus Paddock project, supported by DAFWA and the Grains Research and Development Corporation, has confirmed that plant-available nitrogen in the soil profile is lower across the grainbelt this year compared with the previous four years.
“The average soil nitrogen in the top 90 centimetres of soil was lower in 2014 than the five year average for nine of the 10 grower groups involved in the project,” DAFWA development officer Dr Geoff Anderson said.
“The biggest change was found in the Central Agricultural Region, where the WA No Till Farming Association’s Northam and Cunderdin sites had 50kg N/ha, which had been above 100kg for the previous four years due to an accumulation of surplus nitrogen. The shift is significant when you consider that about 45kg N/ha is required to produce 1t/ha of wheat.”
Concerns about low soil nitrogen were also reinforced by monitoring undertaken by the Facey Group in the Upper Great Southern, as well as by a University of Western Australia trial with the Liebe Group in the Midwest.
For more information about nitrogen deficiency visit DAFWA’s website agric.wa.gov.au and watch for more local information in local AgTactics and AGMEMO newsletters.