Beware pitfalls of min-till as well as pluses
BEWARE, minimum tillage could create as many soil structure and environmental problems as the plough and is not the fail-safe system its advocates suggest.
Arable farmers need to be warned of the pitfalls as well as any potential benefits, says the Environment Agency.
"Get it wrong and surface compaction problems are created that have more damaging consequences for the environment than the plough," says the EAs Richard Smith.
"The plough, used in the wrong conditions, can create compaction problems, but at a much greater depth. Surface compaction creates rain wash, flooding and structural problems that have an impact both on and off the farm."
Environment Agency surveys have shown that in some flood-hit areas during 2001 between 19% and 49% of the land had soil structure problems.
IGER and IACR Long Ashton research has shown that erosion caused by surface run-off from soil with a poor structure is huge compared with run-off from a well structured soil.
"Although soil compaction has been occurring for generations, it is now much more widespread and can, therefore, significantly affect down-stream areas," Mr Smith says.
Minimum tillage can improve organic matter levels near the soil surface to improve stability, but it is still vulnerable to compaction when worked in less than ideal conditions.
Good structure can be achieved by minimum tillage, but the Environment Agency warns there is less room for error. If compaction does occur it is near the surface giving a greater risk of water running off with soil, nutrients and pesticides to pollute ditches, streams, and rivers.
Mr Smith doubts if there is a single preferred cultivation system to prevent erosion and protect the environment.
"The aim should be to ensure the soil acts like a sponge. This can be achieved by a range of tillage practices. Farmers need to be extra vigilant and keep an eye on soil structure, because the scope for error seems to be getting larger, and therefore the problems are also more acute," Mr Smith concludes. *