Devon and Cornwall farmers are being told by the Environment Agency to guard against run-off during and after harvesting their maize crop this year.
A wetter than usual summer means there is a risk maize crops will not mature until late autumn in some areas, the agency says, which could lead to a late harvest when soils are wet due to seasonal rainfall.
Tractors and loaded trailers can cause soil compaction when harvesting in these conditions, potentially leading to an increase in run off which could result in local flooding and pollution of nearby watercourses.
The Environment Agency says farmers in Devon and Cornwall should loosen the soil after harvest if compaction has occurred.
It explains that attention should be paid to compacted headlands and wheel ruts acting as pathways for runoff.
EA project manager James Wimpress says: “Harvesting later than 1 October can be risky as soils may be soft following rainfall and prone to compaction. This can lead to increased runoff over the winter.
“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”.
The EA is also recommending farmers in both counties to consider growing other types of crops instead of maize in future due to the likelihood of climate change leading to more extreme weather.
Mr Wimpress added: “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.
“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.”
The Environment Agency warns that it will take enforcement action if it finds that reasonable precautions to prevent pollution, which include the choice of crop and associated agricultural practice, have not been taken.