Progress reports Soil: tree interactions

In recent years there has been an increasing interest in trees as an important component of the agricultural system. Initially this was focused upon the role of trees planted together with arable crops in some form of agroforestry system, and this chiefly in the tropics and subtropics (see, for example, Nair, 1983). Increasingly, however, with the continuing surplus production of agricultural produce within many countries of temperate climates, there have been proposals to take land out of arable or grass production and replace it with some form of woodland. This trend has been discussed in some detail and is being strongly promoted in the United Kingdom, and it seems apparent that if the political will is there, a European Economic Community wide adoption of such changes in land-use policies may be introduced in the near future. Malcolm Bell of the National Farmers Union was quoted in the Guardian (11 February 1987) as saying that ’If land is to be removed from the production of grass or arable crops, then forestry in various guises is probably the only satisfactory use for this spare land’. In reviewing the prospects for alternative agricultural strategies within the agricultural framework of the United Kingdom, Carruthers (1986) suggests that some form of forestry provides ’a promising alternative land use ’ to current agricultural activities. Government agencies and departments have, in the last few years, taken an active role in encouraging a tree-planting programme. The main thrust of these policies has been to encourage the planting o