Key Points
- Two fertiliser rates (45 kg N/ha and 183 kg N/ha) were applied to two paddocks in Northland to test maize yield response to N fertiliser in a high soil N environment.
- In the long-term pasture paddock, there was no yield response to N fertiliser applied four weeks after sowing, and both N fertiliser treatments increased soil mineral N.
- In the six year maize paddock, an economic yield response to N fertiliser was found. Soil mineral N decreased in the Low N treatment and increased in the Full N treatment.
- Growers should use considerably less fertiliser N on paddocks coming out of long-term pasture.
- The Maize Calculator underestimated yield response to N fertiliser in this high N environment. The AmaizeN forecaster currently being developed will address this.