IMPACT OF WHEAT STRAW MULCH ON UTILIZATION OF RAIN AND SNOW RESOURCES IN ARID LAND OF CHINA

摘要

Agricultural production plays an essential role in national economy in arid and desertif ied areas . Hexi corridor of Gansu Province is a typical representative in such areas. There are more than 10 million mu of cultivated land, accounting for 18.4% of the province total, however, its grain production makes up 31.9% of the total of the province. Thanks to the sufficient light and heat resources, per unit grain yield here is one to two times that of the other places in the province. Moreover, it favours to develop commercial-grain-dominated production along side diversified economy of farming and side-line occupations. But as farmlands here are enclosed by vast extent, of gobi desert, they are characterized by the so-called "oasis agriculture". Influenced by the "effect of rope for airing clothes", the scattered oases have an annual average evaporation of 2020mm due to the impact of seasonal heat waves. Precipitation is relatively small, it decreases from 200mm to less than 50mm from east to west, and from south to north. The maximum precipitation for a single event is generally no more than 30mm with aridity ranging between 4.5 to 8. As agricultural production here entirely depends on irrigation with glacier-melt water, it has long been known as a irrigated agricultural area.