Practical research into the economic value of different nitrogen application strategies is equipping Mungindi wheat growers with valuable management guidelines to maximise crop profitability.
The ability to better match nitrogen demands with seasonal conditions would enable growers in the north western cropping belt to make more targeted management decisions based on potential costs/benefits to their business’ bottom line.
A three year study funded through the Grains Research and Development Corporation’s (GRDC) Grain and Graze project has assessed the application of nitrogen at various crop stages and the resulting impact on volatilisation, yield, protein and profitability.
Conducted by the Mungindi Cropping Group during the 2012, 2013 and 2014 seasons, the trials were established on local properties Bullawarrie and Collybidgelah as grower-run strip trials with results collected at harvest.
A standard rate of 55kg per hectare of nitrogen was applied as urea and initially the treatments included control (no N), 55kg applied pre-plant, 55kg applied post-plant and pre-emergent and 55kg N applied post-emergent.
These treatments were extended in 2013 to pre-plant N spread (80kg/ha urea), pre-plant N incorporated by the planter (80kg/ha urea), control (no N), post-plant and pre-emergent (80kg/ha urea), half pre-plant half early tillered (90kg/ha urea) and half pre-plant and half when a minimum of 10mm of rain fell (90kg/ha urea). Similar treatments were undertaken in 2014 and the Collybidgelah site was added to the project.
Results from the trials suggest that post plant applications of nitrogen could deliver yield benefits, particularly if applied early in the season according to trial coordinator and Department of Agriculture and Fisheries (DAF) extension agronomist Jo Weier.
“The 2012 trial at Bullawarrie, demonstrated that 55kg of N applied either pre-plant of post-plant pre-emergent yielded about 1.2 tonnes/ha more than the control,” Ms Weier said.
“Given that the most common practice for N fertiliser in the Mungindi area was to apply 80kg/ha of urea at planting, we amended the rates in 2013 and 2014 and added some additional treatments.
“In the 2013 Bullawarrie trial we saw the post-plant pre-emergent applications of N yield the highest while at the same time, we saw very little difference in grain protein which ranged from 11.6% to 12.1% across the treatments.”
In 2014, the trials on Bullawarrie and Collybidgelah assessed the N treatments for their impact on yield, protein and gross margin.
At Bullawarrie, the difference in yields between all treatments was marginal at only 46.3kg/ha with the highest yielding treatment being the control (no N) and the lowest yielding treatment half pre-plant half early-tillered.
Using figures of $540/t for urea and a wheat price of $280/t, this translated to the control treatment returning close to $50/ha more than the other treatments.
At Collybidgelah, the yield results varied by 199.2kg/ha between the highest yielding treatment, half pre-plant half early tillered, and the lowest yielding treatment, the control (no N). On a profitability analysis the half pre-plant half early tillered treatment returned $35.89/ha more than the control.
“The trial has outlined the potential value of splitting nitrogen applications in wheat,” Ms Weier said.
“Growers within the Mungindi Cropping Group have gained a clearer understanding of when to apply nitrogen to maximise yield as well as benefiting from increased flexibility to adjust to seasonal conditions.”
Caption: Department of Agriculture and Fisheries (DAF) extension agronomist Jo Weier.
Elise McKinna, DAF Media & Communication Officer
07 3087 8576
Sarah Jeffrey, Senior Consultant, Cox Inall Communications
08 9864 2034, 0427 189 827
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