Dryland Agriculture: Long Neglected but of Worldwide Importance
- Bobby A. Stewart and
- Parviz Koohafkan
Dryland areas occur widely in all continents of the world. Thirty-eight percent of the world's land surface is classified as semi-arid or dry subhumid, and there is an additional 7% arid land used primarily for grazing animals. Dry land farming is the growing of crops in areas where water supply constitutes the major constraint and is widely practiced in semiarid and dry-subhumid regions. Soil degradation is a widespread problem in dry lands and largely results from wind and water erosion, organic matter depletion, chemical deterioration, and salinization. In the worst cases, desertification occurs. Conservation agriculture is the integration of practices that avoids mechanical soil disturbance, maintains a soil cover by a growing crop or residues of previous crops, and rotates crops. These practices reduce soil degradation and in some cases even restore many of the favorable chemical, physical, and biological properties present in the soil initially following the introduction of crop production. Conservation agriculture is gaining acceptance in many countries of the world but has been most successful in favorable rainfall regions where it is relatively easy to maintain soil cover and rotate a wide variety of crops including legumes. The sparse rainfall and high temperatures in dry land regions are major constraints along with the demand of crop residues for feed and fuel, but adoption of conservation agriculture may be the key to sustainable crop production in marginal areas. Preliminary estimates are that the average yield of cereals in dry land regions can be increased 30 to 60% annually by increasing crop water use by 25 to 35 mm achievable using conservation agriculture.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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