Keeping soil erosion at bay on stubble is vital

31 August 2001




Keeping soil erosion at bay on stubble is vital

By Richard Allison

SOIL erosion was at its highest ever level last winter and allowing this to continue may leave fields unable to sustain high maize yields as topsoil is washed away.

According to the Environment Agencys environment protection officer Chris Westcott, soil erosion also leads to silting of rivers and estuaries, which impairs fish spawning and can result in declining fish populations.

"Compacted and sealed bare soil following maize is at particular risk of erosion as rainwater flows down slopes carrying soil into drains and ditches," he warns.

This prompted the EA to sponsor a Maize Growers Association workshop to demonstrate ways of combating soil erosion on maize stubble and their relative costs. Solutions include minimal cultivation, harvesting maize earlier, barrier ploughing and drilling cereal in the headland.

At the workshop, producers will discuss what needs to be done to stop soil loss following a maize crop, says MGA agronomist Simon Draper. "The group will then decide which treatments should be carried out on the plot using machinery typically found on many farms."

This ensures strategies are practical and do not involve the expense of using contractors. Treatments will be undertaken the next day and the group will revisit the site in November to see how effective each strategy has been to prevent soil wash.

Mr Draper believes the main cause of soil loss is harvesting maize crops too late. "Harvesting maize earlier would allow the following cereal crop to establish well before winter and, therefore, cut down on soil wash."

There will also be a demonstration on how to correctly assess crop dry matter and judge when to harvest. Four different varieties of maize have been grown on the site, all of which will be at different stages of maturity when harvested.

Half of the field will be harvested the day before the workshop, which will be about 2-4 weeks early depending on the variety. Costings will be undertaken to show the economics of harvesting maize early to allow September drilling of the following barley crop.

"Silage starch content is expected to be lower with earlier cutting, but silage will be more digestible. It is a compromise between yield and the consequences of allowing soil erosion to occur," says Mr Draper.

The workshop is being held at Andy Drakes Wilts-based farm where maize is grown on clay loam soils receiving 900mm (36in) of rainfall a year. Erosion problems are encountered in sloping fields, initially ploughing on the field margin has prevented soil entering the nearby stream.

But this was not adequate to prevent soil movement within the field. Last year, further measures were undertaken, including sub-soiling and ploughing strips. But Mr Drake believes more can be done to prevent soil moving within maize fields. Topsoil is the main asset and there is a hidden cost as maize yields decline over time. &#42

Workshop details

The workshop will be held on Sept 13 at East Knoyle, Wilts, costing £10 a person. Application forms and details are available by contacting the MGA (01189-761276, fax 01189-761451).

SOIL WASH CONCERNS

&#8226 Declining maize yields.

&#8226 Consider earlier harvesting.

&#8226 Workshop to find solutions.

Workshop details

The workshop will be held on Sept 13 at East Knoyle, Wilts, costing £10 a person. Application forms and details are available by contacting the MGA (01189-761276, fax 01189-761451).

SOIL WASH CONCERNS

&#8226 Declining maize yields.

&#8226 Consider earlier harvesting.

&#8226 Workshop to find solutions.


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