干旱区生态环境知识资源中心

Naiman County is the typical area in Korqin sand land. Chose cultivated land in Naiman County, this article carried on comparative analysis for soil physicochemical properties of cultivated land in different farming years. This included change characteristics of soil physicochemical properties with different farming years in different slope positions (windward slope, sloping top and leeward slope) of cultivated land and quantitative analysis between fanning years and soil physicochemical properties. The results showed that: (1) there were different changes in soil texture in different slope positions of cultivated land in different farming years: at first 15 years, in the windward slope, the soil texture emerged good trend year by year, but after 30 years of farming, the soil texture get significantly worse. In the sloping top and leeward slope, the soil texture was changed for the better trend along with the increase of fanning years. (2) There were different changes in soil nutrients in different slope positions of cultivated land during different fanning years: in the windward slope, fanned from 3 years to 15 years, upward trend showed among the most nutrients and until 30 years, it obviously reduced and drop back to level of the 3 years; There was a rising trend in the leeward part of the nutrients; sloping top was between the middle and more indicators decline in nutrient content than that of increasing. (3) There was relationship between the farming years and soil physicochemical properties: the effects on soil texture was higher than the soil nutrients and correlation between different slope positions was different: in the windward slope, fanning years correlated positively with sand and available P and a negative correlation was found between farming years and other indicators. In the sloping top, farming years correlated negatively with sand, total N, total K, alkaline N and available P, correlated positively with other indicators. In the leeward slope, farming years correlated negatively only with sand and total K, correlated positively with all of other indicators.

Korqin sand land is portion of Songliao subsidence zone, northern is Da Hinggan Ling Mountain and its hilly region, central is the alluvial plain formed by the Xiliaohe River and its tributaries, and southern is distribution of the Yanshan Mountain and loess hills, and it is one of the most serious desertification areas in arid and semi-arid zones of northern China. In recent years, it showed increasing trend in land degradation under human factors and natural factor together. This was a serious threat to the sustainable development of local agriculture [1,2]. Farmland area decreased in production which effected by sand disasters covered over than 30% of all crop planted area [3]. Therefore, protection situation of cultivated land in the area was serious. Land use and management was the most common, most direct and profound factors in affecting soil changes [4,5]. Farming years was one of the most important properties of affecting soil changes in Korqin sand land with serious sandstorms. Research has revealed that years of reclamation has a certain extent on different layers of soil physicochemical properties in sandy grassland in Korqin sand land. With the increase of time of reclamation, fine particle fraction decreased, the coarse and fine sand content gradually increased, soil bulk density increased, soil porosity decreased and the amount of total nutrients in the soil also turn down in arable layer [6]. Under the impact of policy and population factors, a large number of lumps have been reclaimed into cultivated land. Lump was suitable for reclamation, changes in soil quality in different parts after reclamation has not been concerned. To this end, this article chose lump cultivated land as research object, carried on comparative analysis for change characteristics of soil physicochemical properties among different slope positions of cultivated land along with different farming year. Research conclusions can provide theoretical guidance for scientific reclamation of local land.