The Environment Agency has recommended that farmers in Devon and Cornwall consider growing crops other than maize in the future.
It believes these areas are at a high risk of run-off during bad weather – which could become the norm as a result of climate change.
High-risk crops, grown in high-risk locations it said, increase the likelihood of pollution incidents from soil erosion and run-off.
“In some areas it may be better not to grow maize in the first place because the soil and location are at very high risk of runoff during bad weather, causing localised flooding and pollution,” Devon and Cornwall project manager James Wimpress said.
“These areas include steep slopes on sandy soils that are vulnerable to soil loss and erosion during heavy rainfall, and wet clay soils with poor drainage where it is difficult to harvest maize without causing serious compaction and damage to the soil.”
This harvest the agency is asking farmers to loosen the soil after harvest if compaction has occurred, with particular attention paid to compacted headlands and wheel ruts acting as pathways.
A wetter than normal summer has meant that maize crops were late maturing and are therefore being harvested when soils are wet due to autumnal rainfall.
Tractors and loaded trailers can cause soil compaction when harvesting in these conditions it said, potentially leading to an increase in run off which could result in local flooding and pollution of nearby watercourses.
“Harvesting later than October 1, can be risky as soils may be soft following rainfall and prone to compaction. This can lead to increased runoff over the winter,” Wimpress said.
“We recognise that there has been great improvement with managing maize in recent years, including cover cropping and managing compaction, but we would encourage farmers to be vigilant with late harvests, particularly if the weather is wet.”