Fertilisers are one of the major costs for Australian grain growers and GRDC is on a quest to optimise these inputs.
By recruiting novel technologies to learn more about soil function, GRDC is seeking a step change to maximise crop nutrient use efficiency across the country.
GRDC has invested in synchrotron scanning techniques to provide insights into interactions between roots, water and nutrients. Micro-computed tomography and nanoscale secondary ion mass spectrometry are also enhancing insights into soil structure and nutrient supply.
These innovative technologies and foundational research will provide insights to improve nutrient use in the medium term. Meanwhile, GRDC continues to invest in better soil sampling strategies, updated fertiliser recommendations, application methods, flexible pulse and pasture legume species, and harnessing soil biology to reduce nutrient input costs.
Improved soil sampling
Understanding nutrient reserves through soil analysis is fundamental to developing a cost-effective fertiliser strategy. Soil variability within a paddock is common, which can affect nutrient supplies and, in turn, crop yield. More intensive soil testing from each production zone can help growers identify areas where variable fertiliser rates could translate into higher profits.
New fertiliser recommendations
Changing climate and farming systems, together with greater diversity of crop and pasture species, mean fertiliser recommendations need to be reviewed. Acknowledging regional differences in farming systems, GRDC is investing in fertiliser recommendations that are better tailored to specific soil types, changes brought about by soil amelioration, and the integration of better-adapted crops and pastures in farm systems.
Fertiliser application methods
Phosphorus and potassium are less mobile than nitrogen and need to be placed in the root zone, especially in no-till systems. But as nutrient export has increased through higher yields and cropping frequency, soil nutrient reserves are depleted and increased amounts of fertiliser are being applied in deep bands, affecting nutrient dynamics and crop rooting patterns. Research is unravelling these issues to improve fertiliser application methods.
Soil biota
Soil is not simply an inert medium to grow plants – it is a living ecosystem. Soil biology influences the physical structure of the soil, its chemistry and the supply of many nutrients. Microbes are particularly important for nitrogen cycling, supply and symbiotic fixation within farming systems. GRDC investments are supporting the development of new pasture legumes and regionally adapted rhizobia strains and inoculation practices for pulses.
Ultimately, GRDC is endeavouring to ensure growers understand their options to increase nutrient availability and crop uptake. This will occur through enhanced nutrient cycling, nitrogen fixation and improved soil management practices, which will lead to improved profitability and sustainability.
More information: Dr Kaara Klepper, 0477 742 926, kaara.klepper@grdc.com.au; Dr Stephen Loss, 0408 412 453, stephen.loss@grdc.com.au; Dr Rowan Maddern, 0477 707 225, rowan.maddern@grdc.com.au