effect at the beginning of 1993.
Organic farming may involve the replacement of chemical fertiliser by (organic) manure, which is often seen as more environmentally friendly; there is little evidence for or against this view, and more research is needed to compare the environmental costs and benefits of both systems. Such research is difficult because it is not easy to find farms where land conditions and factors influencing production are comparable. Experiments (at Rothamsted, UK) have, however, shown that, while farmyard manure can be at least as effective as a chemical fertiliser in improving yields, the potential for nitrate loss from these manures is greater than from inorganic fertilisers because these manures are often applied throughout the autumn or winter as soil conditions permit and when convenient (Addiscott, 1988). Since timely, accurate applications of nitrogen are difficult, substantial leaching of nitrate and heavy metals is likely to result (UK, MAFF, 1992).
So far, research into organic-type farming has given priority to work on soil fertility (especially chemical fertilisers) or on soil erosion. But more research is needed on biological processes, and soil compaction, before firm conclusions can be drawn on the benefits or otherwise of these farming practices.
Source: Partly from Greenpeace, 1992