Keywords: Fertilisers, Soil fertility, Crop production, Environment, Critical soil nutrient values, Fertiliser recommendations.
From the time some 10,000 years ago that human beings first began to live in settled societies and cultivate the soil to grow plants for food and fibre until the early 19th century, changing patterns of husbandry sought to maximise the benefits of the meagre supplies of plant available nutrients coming from the weathering of soil minerals and the recycling of plant and animal remains.
As simple chemical salts – fertilisers – became available in sufficient quantities for use in agriculture, there was the opportunity to increase food production. This opportunity was realised in the 20th century with the introduction of cultivars with an increasing yield potential and the ability to effectively and cheaply control most weeds, pests and diseases in crops. Today it would be impossible to feed the existing world population without the judicious use of such inputs including fertilisers to supplement the supply of plant nutrients available from recycling and from the soil.
Changing patterns of crop husbandry, early experiments assessing the need for plant nutrients and the changing patterns of fertiliser use are reviewed here. The role of nutrients in maintaining soil fertility and in crop production are related to the efficient use of fertilisers and possible future improvements. The risks of imbalanced or excessive fertiliser use on the economic viability of farming and possible adverse effects on the environment are discussed. Sustainable farming is not only a matter of supplying sufficient nutrients. Examples are given of the need to change cropping patterns to minimise the effects of pests and diseases and how prices and priorities outside the control of the farmer can affect economic viability.
A. E. Johnston, Lawes Trust Senior Fellow, IACR-Rothamsted, Harpenden, UK.
39 pages, 11 figures, 19 tables, 36 refs.