Good husbandry and soil management are cornerstones in tackling run-off and pollution. But growers of risky crops on tricky land may need to make the earth move – literally – to avoid losing precious soil and nutrients.
A recent England Catchment Sensitive Farming Initiative open day in Cornwall showed how earth banks, settlement ponds and profiled storm drains could help.
“Despite achieving the best management for your crops, you may still find run-off carrying soil down tracks and on to roads during heavy or prolonged rain,” said CSF officer Kate Allingham.
This created hazards, caused water pollution, and financial and physical losses. Building banks to slow and hold back water could helpsettle out stones and soil, she said.
Steep fields with poor soil structure, low organic matter and thin crop cover posed particular problems, warned ADAS Associate Bob Watson. “When soil runs from a field the clay and silt travel furthest, carrying a lot of nutrients.”
Farmers should examine their soil structure, work to cut compaction and increase organic matter, he advised. “Drill as early as possible, or modify your rotation so erosion-prone fields are less likely to be bare in autumn or winter.”
Early maize harvesting, under-sowing, and grass strips across fields also helped, as did coarse seed-beds and minimum tillage. Relocating gateways and creating barriers and sediment traps usefully countered run-off, he said.
A case in point
John Wallis’s Trenow Farm, near Penzance, suffered serious soil erosion for years, culminating in amassive soil slick on a road in 2003.
“If we had another event like that we’d end up with no soil in portions of the field,” he said.
“We’ve got sloping, sandy soils and high-risk crops – it was an environmental nightmare.”
The 40ha (100-acre) farm grows early potatoes, winter cauliflowers and other vegetables.
Subsoiling was his first remedial action. He then worked with neighbour David Jeffrey to move gateways, build earth banks and dig sediment pits.
“Water used to cascade through the gateways and across the meadows below carrying tonnes of soil. By building catch pits where the gateways were, and opening new gateways at the tops of the fields, we kept the rainwater in the field.”
To channel storm water away from the pits safely, Mr Wallis piped it directly into a grassy ditch to stop it flooding the field.
“There’s still some erosion because perennial grasses and weeds have not yet established. We plan to re-profile the waterway and plant its entire length with rough grasses to bind the soil together and filter out coarse particles.”
The cost, excluding his own labour, was about £800, but he has not had to clean the road since.
“It’s made a huge difference and is good for public relations. And there’s a definite financial gain – we don’t have to spend so much time cultivating.”