FARMING - CLOSING THE CYCLE

The natural cycle of plant and animal life involves recycling material s through the open environment. Thus carbon dioxide and many waste sub stances are released to the soil or atmosphere and returned to be take n up by plants. Modern agriculture has intensified the production of m any substances, with unwanted effects on the atmosphere (including glo bal warming and acid rain), water and soil. Moreover, because most dro ps are grown as monoculture, competing plants, and pests and diseases, are controlled through a wide range of agrochemicals which also affec t the environment; herbicides remain a major case of drinking water fa iling to meet the required standards. A 'clean technology' approach is urgently needed, and current research is showing the way. Research on the nitrogen cycle indicates, for example, that nitrogen losses from intensive dairy production can be reduced by up to 70%; however, chang es to the whole farm system are needed to achieve results. Both engine ering and biological approaches offer ways of reducing pesticide use; we can use computer control and decision support to improve the precis ion with which chemicals are applied; we can seek new understanding of chemical-insect-plant interactions which allow new control techniques (such as semiochemicals, which influence insect behaviour) to be deri ved. Agriculture can also provide a sustainable source of clean energy and could also supply industrial products such as oils and fibres, re ducing our dependence on petrochemicals.