关键词: 沙地土壤, 有机碳, 全氮, 空间分布, 科尔沁沙地

Abstract: Discussed in this paper are the spatial distribution pattern of organic C and total N contents of sandy soils in relation to the relative height of soil sampling sites along the transect from irrigated cropland, rainfed cropland and shifting sand, and the vertical distribution in the soil profile of irrigated cropland in Horqin Sandy Land. It was found that organic C and total N contents in the depth of 0~10 cm of sandy soil present very close relations to the relative heights of soil sampling sites. Contents of the organic C and total N decreased with the increase of relative heights of sampling sites from irrigated cropland to rainfed cropland, while decreased with the decrease of height of sampling sites from rainfed cropland to the shifting dune. The total N content has a very significant relation to the organic C content. Taken the rainfed cropland only into account, the sandy soil organic C and total N contents at the depth of 0~10 cm have much more significant relations to the relative heights of sample sites. The above relations show that there is the possibility to predict the changes of organic C and total N when the relative heights are known, or to predict the total N content when the content of organic C is known, or vice versa. The vertical distribution of organic C and total N contents in irrigated cropland soil presents a pattern of fluctuation with the alteration of clay/organic layer and sandy layer. The total N content changes correspondingly to the variation of organic C too. For practice, it is recommended that for efficient utilization of the land resource in Horqin Sandy Land, cropping should be focused on the relatively lower land, and avoid reclamation of the higher land or even the already-cultivated rainfed cropland at higher site should be turned to grassland.

Key words: sandy soil, organic C, total N, spatial distribution pattern, Horqin Sandy Land