A new approach to fertiliser management that investigates how different wheat and canola genotypes respond to fertilisers will help graingrowers develop better nutrient management practices and reduce the financial and environmental costs of wasted fertiliser.
Recognising that fertiliser is a graingrower’s greatest single expense, with annual farm input cost at 16 percent, the Crop Nutrition group at The University of Western Australia (UWA), led by Professor Zed Rengel, is examining the optimal management of potassium (K), nitrogen (N), sulphur (S) and phosphorus (P) for wheat, barley and canola.
A novel approach to optimising K management measures genotypic tolerance to soils with low K availability.
UWA Institute of Agriculture researcher, Paul Damon, investigated the magnitude of K efficiency variation of canola and wheat genotypes and discovered that managing this genetic variation could enhance the productivity and sustainability of cropping systems.
“While canola genotypes responded differently to K availability and varied in K efficiency during vegetative growth in the Grains Research and Development Corporation supported trials, Wesbarker and Rainbow were K-efficient and could improve canola yields on soils with low K availability,” he said.
Grain yield and shoot biomass of wheat varieties also differed significantly in response to low soil K availability during the vegetative growth phase and at maturity.
“While Nyabing and Nabawa could tolerate low K concentrations in shoot tissue, Carnamah and Wyalkatchem were able to maintain a high harvest with low soil K availability,” Mr Damon said.
Split applications of a compound PKS fertiliser (phosphorus, potassium and sulphur) at different depths could also increase crop growth and yield.
Mr Damon said fertiliser depth affected wheat crop nutrient absorption and grain production.
Collaboration with the Department of Agriculture and Food WA in a 2006 GRDC supported Corrigin trial on a loamy sand soil investigated the residual value of fertiliser.
“Split placement of a PKS fertiliser the previous season, half drilled at seven cm depth and half drilled at 18 cm, increased plant growth and grain yield compared to drilling all fertiliser at seven or 18 cm.
“The residual value of PKS split placement from the previous year can be maximised by additional surface application of K fertiliser four weeks after sowing on a K-responsive soil,” Mr Damon said.
UWA School of Earth and Geographical Sciences PhD student, Tatjana Balint, in collaboration with the Department of Industry and Resources Chemistry Centre, WA, discovered Australian canola germplasm differed significantly in growth and N and S efficiency.
Her Australian Research Council supported research identified Wesway and Surpass 300 TT as N-efficient at maturity, while breeding lines IB 1363 and IB 1368 showed high S efficiency at maturity.
Professor Rengel said some genotypes used in the trials were no longer in significant commercial production, for example Wesway, while others were used as parental lines in the current breeding programs, such as Surpass 300 for early maturity.
“In future it would be interesting to test advanced breeding lines for N and S efficiency,” he said.
“There was little consistency in N and S efficiency in canola genotypes from vegetative stage to grain maturity, so it’s necessary to test breeding material for these efficiency traits at maturity.”
Soil nutrient management is an essential and cost-effective feature of modern farm management, with plant and soil analyses costing growers less than one percent of total fertiliser expenditure.
“Breeding and ultimately growing nutrient-efficient genotypes will be an important management option for growers to improve fertiliser utilisation, reduce input cost and minimise environmental impacts,” Professor Rengel said.
Professor Zed Rengel 61 8 6488 2557
Paul Damon 61 8 6488 2846
Professor Kadambot Siddique 61 8 6488 7012
0411 155 396