title: Effects of grassland conversion to croplands on soil organic carbon in the temperate Inner Mongolia.
abstract: This study investigated the effects of grassland conversion to croplands on soil organic carbon (SOC) in a typical grassland-dominated basin of the Inner Mongolia using direct field samplings. The results indicated that SOC contents decreased usually with increasing soil depth, with significant differences between the upper horizons (0-30cm) and the underlying horizons (30-100cm). Also, SOC densities decreased with an increase in the depth of soils. Average SOC densities in the upper horizons were 2.6-3.7 and 6.0-8.3kgCm(-2) for desert grassland-cropland sites (sites 1 and 2) and meadow-cropland sites (sites 3 and 4), respectively, with significant differences between grasslands and croplands (P<0.05). However, the SOC densities in the underlying horizons did not significantly differ between the land uses. The SOC densities up to 100cm depth were much higher in the meadow-cropland sites than in the desert grassland-cropland sites, reaching approximately 16 and 6kgCm(-2), respectively. The SOC: total nitrogen (TN) ratios were approximately 10, with no significant difference among the soil horizons of grasslands and croplands. The conversion of grasslands to croplands induced a slight loss of SOC, with a range of from -4% to 22% for the 0-100cm soil depth over about a 35-year period, in the temperate Inner Mongolia.
authors.affiliation: Laboratory of Quantitative Vegetation Ecology, Institute of Botany, Chinese Academy of Sciences, Nanxincun 20, Xiangshan, Beijing 100093, China. wangzp5@yahoo.com
authors.forename: Zhi-Ping
authors.initials: ZP
authors.lastname: Wang
authors.forename: Xing-Guo
authors.initials: XG
authors.lastname: Han
authors.forename: Ling-Hao
authors.initials: LH
authors.lastname: Li
mesh_terms: D000383:Agriculture; D002244:Carbon / Q000032:analysis*; D002681:China; D002980:Climate; D018556:Crops, Agricultural / Q000254:growth & development / Q000378:metabolism*; D004784:Environmental Monitoring; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism*; D012987:Soil / Q000032:analysis*
chemical_list: D012987:Soil; D002244:Carbon