Book of Abstracts
11th IFOAM Scientific Conference
11-15 August 1996, Copenhagen, Denmark
ADAS Terrington, Terrington St Clement, King's Lynn, Norfolk, UK, PE34 4PW.
The conversion of 12 ha to an arable organic rotation has been funded by
the United Kingdom Ministry of Agriculture Fisheries and Food. The objective is to examine the physical and financial implications of conversion, to develop a sustainable stockless arable system and to encourage more farmers to convert. The fertile silt soil at Terrington has been intensively cropped for many years. To build fertility, conversion was two years of red clover cut about four times per year and left as a mulch.
The stockless system is divided into five plots, each of about 2 ha. Following conversion, a rotation of potatoes, winter wheat, spring beans and undersown spring wheat is grown. This is followed by a one-year mulched red clover and the rotation repeated. Conversion has been phased-in over three years. All crops are grown each year, one in each of the five plots. There is no replication. Conversion started in 1990 and the first full crop rotation will be completed in 1996.
Red clover has grown well; gross nitrogen fixation in the cut foliage over the two conversion years has been over 600 kg/ha. Crop yields have been between 60 and 100% of non-organic crops on the farm. Actual yields of wheat have been between 4.9 and 7.8 t/ha, potatoes from 17 to 36 t/ha and beans 2.9 t/ha (only one crop, in 1995). The lower yields have been more than balanced by lower variable costs and good price premiums for wheat and potatoes. This has resulted in better gross margins every year than in equivalent non-organic crops. Most wheats have been of milling quality.
Financial projections over the full rotation, taking account of the reduced revenue from the red clover, still show a significantly greater profitability from the organic system. More experience is needed to determine the sustainability of this rotation.
Cormack, W. F. (1996): Terrington on the Road to Conversion. New Farmer & Grower, Winter 1996, p. 12-13.