Using compost to improve nitrogen use efficiency and productivity of Almonds

Summary

The Australian almond industry is increasingly interested in using composted or pyrolyzed almond hulls and shells (processing residues) and other organic matter (OM) as soil amendments. Several industry players are actively applying these products to their orchards. This is driven by the desire to better utilise a waste stream (currently >250,000t/yr and forecast to double by 2030), improve soil fertility/productivity and potentially qualify for carbon credits. Applying OM is especially challenging to almond production systems as any that remains on the soil surface is likely to be collected as part of the harvest process, potentially exposing the industry to food safety risks. In response, the industry has piloted innovative systems where the OM can be injected below the soil surface. Almonds are a high value and input horticultural crop and the cost of OM application is easily borne if suitable productivity improvement are realised. Nitrogen fertiliser is a major production cost, with approximately 250kg of nitrogen applied to a typical orchard every season, synthetic nitrogen applications also have the potential to leach into waterways with negative environmental impacts. The sustained application of OM can replace some synthetic nitrogen applications, improve soil fertility and orchard productivity, reduce the likelihood of leaching and increase soil carbon content. The aim of this project is to assess existing commercial and research trials to quantify the magnitude of these co-benefits and the increases in soil stored carbon. This information will be used to encourage further development of these innovative practices by the Australian almond industry.

Program

National Rural Issues

Research organisation

The University of Adelaide (PIRSA/SARDI)