Recent HGCA reviews and gap analysis have identified too much uncertainty in the industry in how to assess soil N supply (SNS) – a fundamental component in the assessment of N fertiliser requirements. This uncertainty causes growers difficulty in N management, and compliance with regulations in NVZs.
To achieve consensus across the industry on best practice for estimation of soil N supply (SNS).
To collate and consider stakeholder concerns about estimation of SNS and determine consensus on uncertainties and their solutions. Unpublished work and data will be reviewed and the key uncertainties in soil sampling, handling and analysis will be clarified by experiment. The predictive value of including deep SMN, potentially mineralisable N, and crop N will be assessed at site-seasons, to determine best practice for direct measurement. A cost-benefit analysis of direct measurement versus field assessment (as in RB209) will determine how best to combine these approaches on-farm. The results will then be disseminated to stakeholders and the industry.
Benefits to the industry
Better guidance on use of soil analysis and greater precision in SNS prediction from this project will reduce under-achievement of yield potentials and reduce unnecessary expense on fertiliser. Both of these will provide environmental and financial benefits.