Mr Jeff Kraak1, Dr Rob Norton, Dr Cameron Gourley, Prof Peter Grace
1Fertilizer Australia
Biography:
Cameron Gourley has a passion for improving nutrient management standards and nutrient use efficiency, with expertise in farm nutrient flows, fertiliser use and soil test development and interpretation. Cameron worked for 38 years in pasture and animal production research with Agriculture Victoria and currently manages Soil Water and Nutrients Consulting. He has national and international roles with The University of Queensland, the Australian fertilizer industry FertCare® program, and as Regional Director for Oceania for the International Nitrogen Initiative.
Abstract:
Australian agriculture has moved from extensive to more intensive systems. Nitrogen (N) fertiliser use has increased 9-fold since 1960. Legume species also supplement fertiliser N, but N fixation is challenged by a decline in land area, lower biomass and weak symbiosis. The relatively low N fertiliser rates predominately used for extensive cropping, at around 30-70 kg N per ha, makes up around 66% of all N fertiliser used. Other industries such as horticulture, dairy, cotton and sugar each consume less than 10% of N fertiliser used.
A recent N review provides an assessment of fertiliser use, nitrogen use efficiencies (NUE) and losses for agriculture. Fertiliser use and commodity data indicated average national NUE for wheat, other cereals, canola, cotton, and sugarcane, were 0.82, 0.68, 0.88, 0.48 and 0.44, respectively, while dairy production indicate an industry average NUE of 0.26. Of note are substantial cropped areas where NUE is >1, effectively drawing down soil N and organic matter.
A recent meta-analysis of national N2O emission factors (kg N as N2O per kg N fertiliser applied) for major production systems ranged from 0.17% (non-irrigated pastures) to 1.99% (sugar cane).
We propose policy approaches should prioritize better management of N inputs, particularly where surplus N may impact valued environmental assets such as the Great Barrier Reef, coastal estuaries, and inland water resources, but also where high NUE resulting in longer-term soil N depletion. Strategies should (1) encourage a greater use of farm and paddock-scale N budgets, soil and plant testing, and precision agriculture tools to better balance N inputs and outputs, and (ii) incentivize the use of nitrification inhibitors to reduce N2O emissions.