Key points
- This three year programme of work focuses on nitrogen fertiliser decisions for maize, potato and leafy green crops. This Update summarises the potato component of the project.
- The Quick Test Mass Balance approach is an effective method for informing in-season N management decisions for potato growers.
- Nitrate Quick Test strips can be used to estimate mineral N levels in the soil at any time during the crop’s growth. They may be used as a cost effective substitute for the mineral N test, particularly for top soil samples (0–30 cm depth), where nitrate-N is the predominant form of mineral N.
- Quick Test estimates of soil mineral N levels can be used for fertiliser mass balance calculations to inform in-season N management decisions.
- N FertSD = [Crop NTotal – Crop NSD] – Soil Min NSD – Soil Org Nmineralised. Information about the potential crop demand and the soil nitrogen supply is required.
- The mass balance calculation for a side-dressing decision is:
- The mass balance calculation can either verify the fertiliser plans for the crop are correct, or support less fertiliser being applied. It can also indicate more fertiliser should be applied to reach the potential crop yield.