19 May 1995

Integrated trials point way to improve profits

SEVERAL pointers to better profits are emerging from integrated farming system trials in Leics.

The work is part of a comparison between conventional, integrated farming and organic trials at CWS Agricultures Stoughton Estate. The Focus on Farming Practice initiative was launched by CWS, Hydro Agri and Profarma last year.

No firm conclusions can be drawn yet, as the IFS experiment was only established in autumn 1993, says project manager Alastair Leake. But the heavy soil site is providing a stiff test for some of the methods being tried, with encouraging results.

Work with cover crops and their effect on soil nitrogen levels have been studied, giving results which are the reverse of what was expected, says Mr Leake. More leachable nitrate was found in soils planted with cover crops than under natural regeneration. Autumn cultivations needed to establish these crops speed nitrogen mineralisation on the heavy soils, he explains.

These results conflict with Codes of Practice and integrated farming guidelines which encourage cover crop use, notes Mr Leake. "I was concerned at first, and wondered what we had done wrong." But ADAS found similar results on the same type of soil, he explains.

"Most work on cover crops has been done on light land where they have been shown to work. It shows how site-specific results can be, and this should be borne in mind whenever protocols are drawn up."

A new wheat drilling system is also proving its worth. Preparation is conventional enough – after light cultivations to encourage regrowth, a low-rate glyphosate (as in Roundup) is applied in early October. Target drilling date is the middle of the month to reduce weed burden.

Seed is then drilled into the resulting mat with a Rau Rotosem machine which cultivates, incorporates, sows and rolls in one pass. This uses less energy and produces better soil structure than conventional cultivations.

"Establishment was very good," says Mr Leake. Work rates of about 1.6ha/hr (4 acres/hr) were achieved, and, including stubble cultivation, was £21.60/ha (£8.74/acre) cheaper than the conventional method.

Fewer weeds germinated after the treatment as exposure to dormancy-breaking light was greatly reduced. Weed growth was slowed by better crop competition – seed is scattered by the machine, avoiding bare rows of soil between drills that allow weeds to develop unchecked.

The need to control surviving weeds is based on threat to yield and weed seed return. Highly competitive ones like wild oats and cleavers leave little room for manoeuvre. But more benign types like chickweed and speedwells can be assessed by comparing ground cover with that of the crop.

With practice, this can be done by field walking to assess likely yield loss and fine-tuning application rates to stop that happening, explains Mr Leake.

Efficacy reduced

A low-rate residual herbicide was tried on some of the wheat this spring. But dry weather reduced its efficacy and mechanical weeding was needed to clear weeds. Other areas are being treated with low-rate contact materials aimed at specific problems. Both methods will be compared with conventional autumn residual treatments.

Slugs are a problem on the heavy land site. Rather than treating whole fields, insulated refuge traps are used to monitor numbers before drilling. These non-baited sites give a good indication of likely damage, says Mr Leake. Results are assessed along with seed-bed, weather and wet areas so doses can be tailored and bad patches can be treated.