Phosphate nutrition for maize
At a recent FWAG event in Devon, Jon Myhill from the Maize Growers Association shared findings showing no yield penalty from omitting DAP fertiliser (18-46-0) and manure applications on soils at P Index 2+, and only minimal impact at Index 1.
Because many farms in livestock areas already receive plenty of P from manures building soil P levels, DAP is often unnecessary and therefore can provide a cost saving. Maize establishment is more influenced by soil temperature, moisture and compaction than phosphate fertiliser. This approach is especially important in areas such as the Somerset Levels and Axe catchments where excess P is a significant issue to water quality.
Top tips:
- No fertiliser containing P is necessary on soils at P index 2 or above
- Ensure nutrients from manure applications do not exceed the soil and crop requirement
- Trial leaving a strip without it DAP if interested to know whether this will have an impact
- Plant in good soil conditions that have good levels of organic matter
Jon also highlighted delaying N applications, with foliar N until July–August, as this better matches the timing of crop demand, improving efficiency and reducing waste.
As always with maize, careful assessment must be given as to where this high risk crop is safe to plant. Consider slopes, size of field, soil type, connectivity to water/road and maize variety. Under the Farming Rules for Water, it is illegal to cause over 1 ha of soil erosion and wash. FWAG can support you in your assessment of low-risk fields for cropping and bespoke mitigation measures.
Sammy Read, Farm Environment Adviser. March 2026