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Australia - Strategic P placement offers yield opportunities for northern growers


Australia
April 7, 2014

  • Native soil fertility is declining in northern region farmland due to grain production.
  • Correct phosphorous (P) nutrition can improve productivity and profitability by improving system Water Use Efficiency (WUE) and returns on other crop inputs like nitrogen (N) but only if other nutrients are adequate.
  • Deep placement of P can be likened to “money in the bank” in northern region soils due to its residual value and therefore availability for subsequent crops.
  • Testing the topsoil and subsoil for P and potassium levels is critical prior to undertaking any fertiliser program to ensure the likelihood of a P response.

A strategic rethink on the placement and management of phosphorous (P) could deliver valuable long-term productivity improvements to farming systems across the northern region and address the enduring challenge of subsoil fertility decline.

http://www.coxinall.com.au/wp-content/uploads/2014/04/Mike-Bell1.jpg

That’s the opinion of Dr Mike Bell (pictured) from the University of Queensland’s Alliance for Agriculture and Food Innovation (QAAFI), who said deep placement of P could be likened to “money in the bank” in northern region soils due to its residual value and therefore availability for subsequent crops.

Speaking at the recent Grains Research and Development Corporation (GRDC) Northern Research Updates in New South Wales and southern Queensland, Dr Bell said P had traditionally been considered as a nutrient applied at planting in the seeding furrow to support the establishment of grain numbers at floral initiation.

However, he said its availability was also critical in later crop growth to establish a high tiller density in cereals, develop a vigorous root system, grow biomass and ultimately fill grains.

“We know the application of P in the seeding furrow only supplies us with a small amount of P, and although that’s a critical amount of phosphorous it’s only a small amount, and the crop is actually foraging for the bulk of its phosphorous from other parts of the soil profile,” he said.

“It’s those other parts that are rundown and that’s where we need to look at P fertiliser placement in the future.

“Because the residual value in our clay soils is so good and we want to deep place, which means soil disturbance, moisture loss and so forth, the other issue to consider is that we are relying on P management across a crop cycle or a rotation rather than a crop-by-crop basis.”

As soils in the northern region exhibited significant variation in P status, Dr Bell said it was imperative that growers tested both the topsoil and subsoil for P and potassium levels before undertaking any fertiliser program to ensure the likelihood of a P response.

“Getting P nutrition right can improve productivity and profitability by improving system Water Use Efficiency (WUE) and returns on other crop inputs like nitrogen (N) but only if other nutrients are adequate,” Dr Bell said.

“Growers looking to raise grain crop yield potentials above what is normally experienced should ensure that there is adequate N available to achieve that higher yield goal.

“Also those diverting some of the P fertiliser used in starter applications to periodic deep P applications should make sure that the rate applied is still adequate to meet seedling P demand, with the key factor likely to be uniformity of fertiliser distribution along the seeding row.”

A team led by Dr Bell is conducting trial work supported by the GRDC assessing the costs and returns of deep P placement in cropping systems using simulated crop yields in combination with trial data from sites in northern New South Wales and Queensland.

Part of the trial work focusses on yield responses to different P rates across the initial crop as well as subsequent seasons within a crop rotation.
 



More solutions from: GRDC (Grains Research & Development Corporation)


Website: http://www.grdc.com.au

Published: April 7, 2014


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