Key Points
- Weather records from Winchmore were analysed to determine the size and frequency of rainfall events that might cause leaching of fertiliser N applied to maize crops. Drainage losses below 1m for the wettest season (1978-79) were also calculated.
- This region has a low risk of leaching of fertiliser N applied to maize crops, even in irrigated situations. By the time drainage below 1m occurs, there has been substantial crop N uptake.
- Soils with low available water capacity have a greater risk of N leaching and growers should split fertiliser N applications and apply the majority of N fertiliser four to six weeks after sowing.
- Drainage over the following winter is likely so growers should only apply as much fertiliser N as required by their crop and take into account the existing soil N pool when determining application rates.