Grassland conversion into cropland and further into abandoned land may result in substantial changes when such conversion neglects the historical context of the land use pattern in question in most cases. The objectives of this study were to examine the effects of land use shifts on soil organic carbon (OC), total nitrogen (TN) and total phosphorus (TP) in a meadow steppe in eastern Inner Mongolia. Four sites within 50 km were selected as replicates, and within each of the four sites, the plant and soil properties were investigated separately for three land use types, grassland, cropland and abandoned land from cropland, to reveal the effect of land use changes on soil nutrient contents and stocks. We found that cropland had the highest canopy biomass, whereas grassland maintained the highest root biomass. Significant decreases in OC and TN contents occurred mainly in the 0−20 cm soil layer with the conversion of grassland into cropland, whereas TP contents significantly increased in the 10−30 cm soil profile. Abandonment obviously increased the soil OC and TN contents in the 0−20 cm soil layer compared with cropland, although the levels of native grassland were not reached. The C:N, C:P and N:P ratios were highest in the entire soil profile for the grassland followed by the abandoned land and then the cropland. Changes in nutrient stocks with land use shifts showed similar trends as those in the relevant nutrient contents, but the change ratios of stocks among different land use types could be significantly underestimated due to the cultivation-compaction effect. Thus, we concluded that the abandonment and maintenance of native grasslands should be adopted to protect and maintain the soil organic matter and nitrogen in the meadow steppe of Inner Mongolia.

如果在大多数情况下，草原转化为耕地并进一步转化为荒地可能会导致实质性变化，而这种转化忽视了所讨论的土地利用模式的历史背景。这项研究的目的是研究内蒙古东部草甸草原土地利用变化对土壤有机碳（OC），总氮（TN）和总磷（TP）的影响。选择50公里内的四个地点作为重复样本，并在四个地点的每个地点分别对三种土地利用类型（草地，农田和农田弃耕地）的植物和土壤特性进行调查，以揭示土地利用变化对土地利用的影响。土壤养分含量和储量。我们发现农田的冠层生物量最高，而草地的根系生物量最高。随着草地向农田的转化，OC和TN含量显着下降主要发生在0-20 cm土层，而10-30 cm土层中TP含量显着增加。尽管没有达到原生草地的水平，但与耕地相比，弃耕明显增加了0-20 cm土壤层的土壤OC和TN含量。在草地的整个土壤剖面中，C：N，C：P和N：P比率最高，其次是荒地，然后是农田。随着土地利用方式的变化，养分储量的变化趋势与相关养分含量的变化趋势相似，但是由于耕作效应，不同土地利用类型之间的养分变化率可能被大大低估。从而，