科尔沁沙地生态系统典型土壤养分空间分布特征

通过对位于科尔沁沙地中南部的奈曼旗中部沙地灌溉农田、旱作农田和流动沙丘土壤有机C和全N含量空间分布特征的分析发现:由灌溉农田、旱作农田到流动沙丘,土壤10cm深度内有机C和全N的含量与相对高度的变化密切相关。随着相对高度的增加,上述土壤的有机C和全N的含量逐渐减少,而且全N含量比有机C含量与相对高度的相关性更为显著。从旱作农田到流动沙丘有机C和全N的含量随着相对高度的减小而减少。如果不考虑灌溉农田和流动沙地土壤,旱作农田土壤有机C和全N含量与相对高度的相关性显著程度更高。科尔沁沙地中部沙质灌溉农田土壤全N和有机C含量的垂直分布呈锯齿状,表现为明显的多'峰谷'性,这种变化与土壤的粘土层/有机质层和沙层交错分布的特点有关。尽管研究区的土壤发生了明显的空间变化,但是土壤的全N含量和有机C含量之间依然存在着显著的相关性

A Spatial Distribution Pattern of Organic C and Total N of Sandy Soils in Horqin Sandy Land

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.