Crop Coefficients

Abstract

There is increasing awareness all over the world of the negative effects of conventional agriculture and the need to change traditional agricultural practices. The key problem of conventional agriculture faces, especially in the tropics, is the steady decline in soil fertility, which is closely correlated to the duration of soil use. This is primarily due to soil erosion and the loss of organic matter associated with conventional tillage practices, which leave the soil bare and unprotected in times of heavy rainfall, wind and heat (Derpsch, 1998). To counter this a new concept of farming is evolving, which has been termed «conservation agriculture». Conservation agriculture maintains a permanent or semi-permanent organic soil cover. This can be a growing crop or a dead mulch. Conservation agriculture aims to conserve, improve and make more efficient use of natural resources through the integrated management of available soil, water and biological resources combined with external inputs. It contributes to environmental conservation as well as to enhanced and sustained agricultural production (FAO, 2001). No-tillage, direct sowing, direct drilling and conservation tillage all aim to achieve conservation agriculture.