The Arable Group is taking a four-pronged trials approach in attempting to research ways growers can reduce their reliance on fertiliser and diesel.

“Fifty percent of the energy used to produce a tonne of wheat comes from fertiliser, and another 25% from diesel use,” the group’s Ron Stobart said. “If we can be seen to be reducing our N inputs and our global energy contributions, that’s a positive message for farmers to give out.”

Some of the trials were looking at the viability of different cultivation techniques, such as strip-tillage that tilled only one-third of the soil, using green compost wastes for their fertility values, and using cover crops, such as mustard or fodder radish to build fertility, he said.

But perhaps the most extreme strategy being trialled was under-cropping with various clovers, as used in organic agriculture. “We shouldn’t be shy in trying something that works for the organic sector.”

The idea was to use the clover as an additional N source by knocking it back with herbicides to get it to release some nitrogen at the right time, Mr Stobart explained. “I’d be quite happy if we could make savings of 50kg/ha of nitrogen without any yield penalties.”

In the trials three different types of clover had been tried – a subterranean clover, yellow trefoil and white clover – each established in August before winter wheat was direct drilled through it in October.

The subterranean clover had not really established at all, while the yellow trefoil was far too competitive at the seed rate used. “The future is probably is to use some kind of mixture of something that comes up quickly, but also something that’s a bit longer lasting like white clover.”

Unlike organic agriculture, the key to the success of the strategy could be timely use of chemical herbicides, he said. That was why a lot of the trials effort this year was screening various herbicides. “We’re looking for herbicides for three different roles. We want something that is safe on crop and clover but kills weeds, herbicides that dent the clover to release nitrogen, and finally something that kills the clover.”

mike.abram@rbi.co.uk

TAG crop system trials

* Funded by agricultural charities

* Aim to reduce reliance on hydrocarbons

* Four strands

* Most radical is use of clover undercropping

[pic: On CD – 0079.jpg or similar

Caption: TAG is investigating the potential to use clover as a source of nitrogen to reduce reliance on bagged N, Ron Stobart said]