Research lifts accuracy of soil test analysis
Author: Natalie Lee | Date: 04 Mar 2014
Research is updating ‘critical soil test values’ which is improving interpretation of soil test results and helping Western Australian grain growers make better fertiliser decisions.
Findings from crop nutrition research and guidelines to help growers conduct soil testing and apply fertiliser effectively are outlined in a Soil Testing for Crop Nutrition Fact Sheet and More Profit from Crop Nutrition Ground Cover Supplement.
Department of Agriculture and Food (DAFWA) researcher Ross Brennan said research funded by the Grains Research and Development Corporation (GRDC) had collated more than 1892 WA crop nutrition trials and revised critical soil test values and ranges for combinations of nutrients, crops and soil.
Critical soil test values indicate if a crop is likely to respond to added fertiliser and are compared with results from soil tests to help growers make informed fertiliser decisions.
“Interrogation of the newly available database for Australian crop nutrition trials has helped to establish the validity of many values used by fertiliser companies and agronomists to support fertiliser decisions,” Dr Brennan said.
“Data analysis of post-1995 experiments was used to generate the new critical values and ranges because they are more relevant to the no-till, stubble-retention systems used by most growers.”
Dr Brennan said that where data existed, critical values and ranges had been produced relating to crop and soil type interactions.
“For example, 67 per cent of the soil experiments in WA included soil pH measurements,” he said.
“Of these, 82 per cent have soil pH in the 0 to 10cm layer of less than 5.5, which can cause production losses.
“Hence, WA critical values have been defined for acidic soils.
“If analysis of soil tests reveals soils that are very acidic, or that soil aluminium is limiting plant growth, growers will need to apply lime to the affected areas.”
Dr Brennan said research in WA had also established that many WA growers had an oversupply of phosphorus.
“Research under the GRDC More Profit from Crop Nutrition II initiative is focusing on how to profitably and safely divert fertiliser dollars into lime applications to overcome the widespread and growing acidity issue across the WA grainbelt,” he said.
The Soil Testing for Crop Nutrition Fact Sheet and More Profit from Crop Nutrition Ground Cover Supplement were contained in the January-February edition of the Grains Research and Development Corporation (GRDC) magazine Ground Cover and are available at www.grdc.com.au/GRDC-FS-SoilTestingW and www.grdc.com.au/GCS108.
Caption: Findings from crop nutrition research and guidelines to help growers conduct soil testing and apply fertiliser effectively are outlined in new GRDC publications. Photo by Emma Leonard.
Ross Brennan, DAFWA
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