5 January 2001

Nutrients parallel

NO big differences in the nutrient status or organic matter levels of soils farmed conventionally or organically can be detected, according to ADAS.

"We have compared potash, phosphate and organic matter levels in the two systems on a range of soils across the country, including farms which have been organic for eight years or more," says Mark Shephard of ADAS Gleadthorpe. "But we have found no differences.

"However, we did discover 50% more earthworms on the organic farms and the soil structure was better. This is important for a system that relies on a crops rooting ability to scavenge for nutrients."

Dr Shephard says he would have expected to find more bio-activity in organically farmed soils. But this was not obvious.

"That is possibly because less carbon in the form of crop residues from lower yielding crops is returned to the soil. We hope to do more work to confirm this."

Lower yields may explain why organic land contains no more nutrient reserves than that farmed conventionally, Mark Shephard believes.