SOIL AND WATER RESOURCES CONSERVATION AND MANAGEMENT FOR AGRICULTURAL PRODUCTION IN DRY AREAS OF UZBEKISTAN

Abstract

Land and water are the most important natural resources and are regarded as the permanent assets in the service of mankind. Agriculture plays an important role in the economy of Uzbekistan. About 15 million people (60% of total population) depend directly or indirectly on agriculture. Twenty to forty percent of the Gross Domestic Product (GDP) is derived from Agriculture. The available land of the republic is 44.4 mha. of which about 11.8 mha are potentially suitable for irrigation including 4.3 mha of existing irrigation area (MAWR,Uzbekis tan, 2000). The other 32.6*mha. is desert pastures, mountains, sandy soils (Uzdaverloiykha, 2000). There is a rainfed arable area of 0.8 mha. Yields in the rainfed area are low but the area makes an important contribution to national grain* production. The average annual precipitation in the plains is about 80-100 mm to the east and south parts of the country the amount reaches 890-1000 mm. During vegetation period precipitation is less; therefore all crops must be irrigated so as to fulfill their water requirements. Main irrigated crops are Cotton, Grain and Vegetables. Commonly used irrigation methods are furrow, border and basin. The crisis of the Aral Sea and its coastal area basin is widely known and do not require detailed description. The Sea has decreased in volume to one-third as much, in water surface area to half of original size and its water salinity has increased fivefold. Excessive emphasis an extension of irrigation system and construction of many medium and small-scale reservoirs hav6 created problems for both the environment and system efficiency during the last 30 years. Particularly, substantial water losses and surplus of irrigation caused by implementation of inappropriate irrigation technologies have led to water logging, soil salinization, and decline of water quality and also have resulted by the aggravation of the Aral Sea status. Currently in Uzbekistan, total agricultural area subjected to salinization is 3.7 mha of which 1.1 mha is the land of medium and highly salinized. iii Uzbekistan has a big potential reserve of the area suitable for irrigation, but water resources limit the development of irrigation. Emphases must be given to bring into use the irrigation methods which will assist in solving problems like irrigation waster saving, improvement of production and conservation of soil fertility and its structure. Keeping in view the above background ICARDA has established as integrated research site at Boykozon farm, in the Tashkent Province of northeastern Uzbekistan. The site represents the typical agro-ecological and mixed farming system of the country. Three advanced irrigation techniques are tested on these fields. Encouraging results of water and soil conservation have been obtained form these studies. The techniques includes use of Joyak (Zigzag) furrows for irrigation of winter wheat crop, the use of Portable Polyethylene Chutes (PPCH-50) with adjustable aperture for irrigation of potato crop, and the use of Marginal waters for irrigition. Results of this study showed that above irrigation techniques have higher water productivity and irrigation efficiency. Soil erosion is decreased from 3.48 t/ha to 0.54 t/ha as compared with traditional irrigation method and Joyak (Zigzag) technique due to reduction in the velocity of water flow in the furrow. In case of PPCH-50 studies it is observed that the water saving up to 50%. of traditionally used amount can be obtained for same yield and soil erosion is reduced from 3.1 t/ha to 0.4 t/ha. Thus, these techniques can be used as improved irrigation method with the purpose of conservation and management of water and soil resources in the dry agricultural areas of Uzbekistan.