A METHOD that determines the ideal fertiliser application for wheat crops - without sacrificing yield or protein content - has been proven to reduce fertiliser input requirement, decrease greenhouse gas emissions and increase net income for graingrowers.
The Director of The University of Western Australia's (UWA) Institute of Agriculture, hackett professor Kadambot Siddique contributed to the seven-year research project, which was led by scientists from Northwest A&F University in China.
The study, recently published in the journal Field Crops Research, aimed to produce high grain yield and protein content for wheat production in China using a high nutrient-use efficiency based fertiliser recommendation (High NUFER) method.
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According to the Bankwest Curtin Economics Centre, WA farmers increased their use of fertiliser fourfold between 1990 and 2018.
Fertiliser was also the main source of WA farm costs at about 18 per cent.
Similarly in China, fertiliser use increased 511pc from 1978 to 2019, with grain production increasing by only 118pc in the same period.
China is the world's biggest producer and user of fertilisers, with numerous reports of fertiliser overuse.
Although chemical fertiliser application is key to ensuring high and stable crop production, professor Siddique said excessive fertilisation reduced fertiliser efficiency and farm economic benefits and caused various environmental problems.
"Over-applied fertilisation has been shown to cause excessive nitrate-N in water, eutrophication and greenhouse gas emissions that threaten drinking water quality and environmental safety," professor Siddique said.
"This study provides scientific guidance for saving costs, increasing farm income and improving sustainable agricultural development in China and other countries in similar situations, such as Australia."
For the study, the research team conducted farm surveys covering 1575 paddocks in 17 of China's major wheat production provinces from 2015 to 2019.
The onfarm information included wheat planting area, varieties, field management, soil nutrient status and fertilisation status.
Wheat plant and soil samples were also collected for measurement and analysis.
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From 2020 to 2021, the researchers verified the High NUFER method in 46 sites across seven major wheat production provinces.
Professor Siddique said the validation experiments in the final year of the study proved that fertilisers were over-applied and often imbalanced.
"It revealed that the recommended fertiliser application based on High NUFER reduced nitrogen and phosphorus fertiliser use without affecting grain yield and protein content, relative to the farmer's previous fertilisation application," he said.
"The reduced fertiliser improved the partial productivity of nitrogen and phosphorous fertiliser and alleviated soil available potassium depletion.
"With the High NUFER method, graingrowers can reduce their fertiliser input, thereby increasing economic benefits and decreasing greenhouse gas emissions.
"Similar studies are urgently needed in Australia and other wheat-growing countries, with the involvement of relevant farmer groups."
