RESEARCH by the Department of Agriculture and Food has found wheat and lupin growers using no-till can improve yields by optimising phosphorus fertiliser placement under variable seasonal conditions.
Department researcher Wen Chen will outline the research at this month’s Agribusiness Crop Updates in Perth, supported by the Grains Research and Development Corporation.
The research and other studies to be featured by Dr Chen have been funded by the department, Murdoch University and by the GRDC.
“The focus of the work is on improving fertiliser management and nutrient use in our cropping systems through precision placement of phosphorus (P) fertiliser and improving soil test interpretations,” Dr Chen said.
“It should enable farmers to make better fertiliser decisions under variable seasonal and soil conditions in WA cropping systems.
“In our soil-crop modelling study, placing phosphorus fertiliser at 8cm depth (or banding) consistently produced higher wheat grain yield than placing at four cm (or drill P with seeds), particularly when growing season rainfall was less than 300 mm, together with the dry conditions early in the season.
“We found no further grain yield responses when phosphorus was placed deeper in the soil profile.
“Lupin responded differently to the placement depths due to its late phosphorus demand in the growing season.
“We found that maintaining phosphorus fertiliser in moist soils through deep banding (14cm) late in the growing season was important to meet the phosphorus demand by lupin, particularly if the potential yield was high but spring conditions were dry.”
Dr Chen said the results were important because fertiliser costs were a significant part of the variable costs in growing crops in WA, and farmers needed to know how to optimise phosphorus placement for better crop yields.
“Improved knowledge on the impact of season on availability of P fertiliser placed at different depths, and how to meet yield potential by placing phosphorus in soil layers that stay moist for longer will help growers optimise fertiliser placement,” Dr Chen said.
Studies were also conducted to improve soil test calibrations and interpretations for canola crops growing in WA in response to the substantial changes in local farming systems, fertiliser practices and crop yield potential since earlier soil test calibrations were developed.
Dr Chen said the surface soil test critical values for phosphorus (P), potassium (K) and sulphur (S) were derived, and these values could be used to determine deficiency or sufficiency of P, K and S for canola production.
“The studies have also highlighted the need in sulphur and some soil type/climate situations, to develop deep soil sampling guidelines, together with better interpretation of the topsoil and subsoil test values to improve current fertiliser advice for canola grain production,” Dr Chen said.
* The department’s 2010 Agribusiness Crop Updates will be held on 25-26 February. Regional Updates for growers will be held during March.
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