Organic Arable Systems at ADAS Terrington OF0112

Project OF0112 contributes to MAFF's main policy focus of encouraging conversion to organic farming methods. It is part of a long term rotational study that began in 1990 as OF0102 and has recently been extended to 2001 as OF0145. The overall objective of these three projects is to evaluate the cost of conversion to organic arable production on a fertile soil, to assess the physical and financial performance of the organic rotation, to identify and overcome limitations to sustainabilty and to compare the results with conventional arable production. The project comprises a field-scale unreplicated systems comparison and associated replicated experiments at ADAS Terrington, and a financial analysis of ten commercial 'linked' organic farms. The silty clay loam soil at Terrington has proved ideal for organic production, primarily because it has very good water and nutrient and retention. As expected, organic crop yields have been less than conventional, averaging 70% for winter wheat; yields have been, on average, double that of the linked farms, and reached a peak of 10 t/ha in 1996. Variable costs have been lower and organic prices have been twice or more that for conventionally grown potatoes and wheat. Crop grossmargins (i.e. the value of the crop harvested minus the drect variable costs of growing it) have been consistently higher from organic than conventional. Even allowing for the lower value of the other three crops in the rotation, i.e. beans, spring cereal and clover (Set aside), overall gross margin from organic was higher than from conventional (average from 1993 to 1997 was 1,878 v 1,290 #/ha). Crop yields and gross margins were generally lower on the linked farms, probably mainly because they were on lighter soils more prone to leaching losses. However, all were viable businesses and had similar profitabilities to conventional farms of their size. The most profitable rotations in cluded potatoes and/or vegetables. In the absence of animal manures and synt