Using soil & plant testing data to better inform nutrient management & optimise fertiliser investments for grain growers
Grains Research and Development Corporation | Published March 9, 2018 - Deadline April 20, 2018
The Grains Research and Development Corporation (GRDC) is a statutory corporation established under the Primary Industries Research and Development Act 1989. It is subject to accountability and reporting obligations set out in the Public Governance, Performance and Accountability Act 2013. It is responsible for planning, investing in and overseeing research and development, and delivering improvements in production, sustainability and profitability across the Australian grains industry. At present soil testing is widely recognised across Australia as the best way to determine supplies of plant available phosphorus, potassium and sulphur, and fertiliser requirements applications needed to meet crop demand. In addition, soil testing can help inform nitrogen and trace element applications, especially when coupled with plant testing, and is critical for monitoring soil acidity, organic matter and other characteristics. Of the nutrients, phosphorus is the most reliably managed through soil testing, and there are good response curves for most combinations of crop, soil type and plant available soil phosphorus levels within the GRDC Better Fertiliser Decisions for Cropping database. Soil and plant testing are the cornerstone of Fertiliser Australia’s stewardship program FERTCARE and commercial analytical laboratories and interpretation services operate across the country. Despite the availability of these services, levels of adoption of soil and plant testing in the southern region are low and appear to have declined from 40% of cropping paddocks in 2008 to about 15% in 2016. Decades of phosphorus fertiliser additions have resulted in some soils now having large amounts of available phosphorus where crops no longer respond to fertiliser phosphorus applications, and in some of these cases, these soils are contributing to eutrophication of waterways. In contrast, other soils, such as the highly calcareous loams and clays in LRZs of SA and Victoria, remain phosphorus deficient, despite many decades of fertiliser additions. Growers that do not monitor soil phosphorus and other nutrient levels are unable to determine whether they are getting a good economic return for their investment in fertiliser. Growing crops in the absence of any information on the supplies of nutrients from soils is akin to driving a car without a fuel gauge. Hence, there appears to be a significant opportunity for better targeted and more efficient phosphorus fertiliser applications based on increased adoption of soil testing. Similarly, soil nitrogen levels before sowing can inform growers and their advisors of the likely supply of nitrogen during the season. Using a budgeting approach based on crop demand (i.e. likely yield and protein) and soil supplies, growers can make informed nitrogen decisions that can be updated during the season as crop yield potential becomes better defined. The poor adoption of soil and plant testing seems to be due to a combination of many factors, including: harsh field conditions when sampling in summer; confusion over the best sampling methods; a lack of trust in results due to sampling and laboratory errors in the past; large temporal fluctuations in soil N; a lack of confidence in interpretation of soil test results and fertiliser recommendations; some growers/advisors prefer simple budgeting approaches based on nutrient removal; some growers favour simple sowing operations with ‘blanket’ fertiliser rates across the farm; and a perception that testing is ‘another cost’ for little return. The GRDC seeks to provide grain growers in the GRDC Southern region with evidence of the usefulness and economic value of well-informed fertiliser decisions, to influence their attitudes and motivation to adopt improved nutrient management techniques. This will be achieved by working directly with growers, FERTCARE accredited advisors and industry across the southern region to demonstrate the process and benefits of soil and plant testing, and improved crop nutrition advice across two seasons. An economic framework will be developed to quantify the likely returns from improved nutrient management techniques and the opportunity to boost farm profit, and these findings will be extended to other growers not directly involved in the demonstration program. The large numbers of soil profile analyses collected by the demonstration program (about 7,000 p.a.) will also provide a useful snapshot of nutrient status and soil fertility in these states, and could be used to highlight emerging issues like soil acidity and declining organic matter. By June 2022, grain growers have increased awareness of the economic value of soil testing and other nutrient management practices to better inform their fertiliser investment decisions and are motivated to invest in testing services based on increased confidence in current tests, and an improved ability to use test results to increase profit, while managing risk. Rates of soil testing in the southern region will increase by 50% above 2016 levels. The project will increase adoption of best nutrient management practices by working directly with growers through advisors and agribusiness, and influencing other growers through broad extension and communication activities. A GRDC budget of up to $1.95M is indicated for this investment dependent upon the quality of the application, expected delivery of outputs and outcomes, and the ability to leverage GRDC funds through co-contributions from partners. The GRDC is focused on delivering value to Australian grain growers; therefore, your application must demonstrate fair market value. Leverage of GRDC funds through in-kind and cash co-contributions is viewed favourably.