Abstract: The area of the meso-low yield land in Altay Prefecture is 103380.8 hm² and occupies 75.8% of the total area of the cultivated land. The meso-low yield land in Altay Prefecture is characterized by extensive distributing, large area, multiple types, and complicated formation causes, and has a good representativeness in Xinjiang. According to the main restrictive factors, the meso-low yield land here can be divided into 8 types, i. e. the types of poor-quality soil, saline or alkaline land, damp land, sloped land, dry land, aeolian-sandy land, lowtemperature land, and extensively-cultivated land, and 17 sub-types. The formation of the meso-low yield land is affected by many natural factors, such as the disadvantageous morphological conditions, harmful physical and chemical nature of soil, frequent occurrence of agroclimatic disasters, drought and waterlogging caused by the bad-distributed water resources, weeds in fields, plant diseases and insect pests, and is also affected by many artifical factors, such as the extensive cultivation, low usage rate of the improved varieties of crops, slack prevention and control of plant diseases and elimination of pests, irrational planting strueture, dampening, salinization or alkalinizaton and swampization caused by irrational irrigation, and poor quality of agricultural ecological environment. It is suggested to take the multiple measures, including the administrative, engineering and biological measures so as to raise the land quality and farming level and improve the agricultural ecological environment. Thus the per unit area yield will be raised, and a virtuous circle from low-yield land to meso-yield land then to high-yield land will be achieved.

Key words: meso-low yield land, formation cause, transformation measure, Altay Prefecture