Degradation of Natural Resources and Measures for Mitigation

Nearly all of the soils under agricultural use show signs of degradation. This is obviously more severe in the tropics and has more dramatic impact than in moderate climate zones. However, the processes and consequences are in principle the same. Most visible signs for these degradation processes are increasing wind and water erosion and, as a result, disturbed water balances. Erosion, falling ground water tables, drying rivers or floods are only symptoms caused in many cases by soil degradation. Particularly important in this respect is the decrease in soil organic matter, and as a consequence, a decrease in soil life and the loss of soil structure. Intensification of agriculture has led, particularly with progressing mechanization, to an intensification of soil tillage. In combination with a decreasing input of organic matter, this has resulted in a reduction in soil organic matter. As a response to dramatic wind erosion problems in the USA in the 1930s, conservation tillage was developed. But only the dramatic water erosion in the hilly parts of southern Brazil led to the development of a completely new kind of agriculture. This agriculture avoids permanently any kind of mechanical soil movement using the already known techniques of zero tillage and direct seeding. Through synergy effects created in the system combining zero tillage with other well-known techniques such as mulching and diversified crop rotations, a sustainable cropping system is established. Conservation agriculture (CA) is actually expanding exponentially in many regions of the world. Experiences with the long-term and large-scale adoption of CA have shown other positive side effects which suggest that this is a globally valid concept for sustainable agriculture