Keywords: Organic farming, Integrated farming, Sustainable agriculture, Food security, Soil fertility, Biodiversity.

The history of Western agriculture is discussed, with reference to organic farming. The rules for organic farming are strict, and forbid the use of conventional fertilizers, hence organic crops are always at risk of nutrient deficiency. The methods used by organic farmers to mitigate this are considered, but all have some disadvantages. Nitrogen can be fixed from the atmosphere by legumes, but phosphorus and potassium have to be replaced to compensate for crop offtake. The nutrient balances are therefore critical, and examples are given.

Integrated farming is a compromise between conventional and organic farming, and has advantages over the latter. In this, excess applications of fertilizers have to be prevented. Pollution, sustainability and food production are also discussed.

P. B. Tinker OBE, DSc., Plant Sciences Department, Oxford University, UK.

24 pages, 6 figures, 9 tables, 35 refs.