中文摘要：

采用物理分组方法分析了长期（1990—2007年）不同施肥条件下灰漠土各粒径矿物颗粒结合有机碳含量和分布差异及其随施肥时间的演变特征.结果表明：与不施肥相比,配施有机肥对增加各有机碳组分的效果最显著,并以砂粒有机碳含量的增速（0.34g.kg-1.a-1）最高,对施肥最敏感;撂荒地可以显著增加不同黏粉粒结合有机碳含量;秸秆还田仅能维持各级矿物颗粒结合有机碳的含量;长期施用化肥不利于各级颗粒结合有机碳含量的增加.从分配比例来看,以粗粉粒（27.9%）和粗黏粒（27.1%）有机碳所占比例最高,是固持有机碳的重要组分;配施有机肥使砂粒有机碳比例显著提高119.4%,细粉粒和粗黏粒有机碳比例却分别降低了40.3%和37.9%,从而提高了颗粒有机碳含量（WPOC）与矿物结合有机碳含量（WMOC）的比值,改良了土壤有机碳性质.长期配施有机肥是增加灰漠土各级矿物颗粒结合有机碳积累和提升灰漠土肥力的最佳方式.

英文摘要：

Physical fractionation technique was used to analyze the content,distribution,and temporal evolution of organic carbon associated with particle-size fractions of grey desert soil under long-term （1990-2007） fertilization.Compared with no fertilization,a combined application of manure and chemical fertilizers increased the organic carbon associated with particle-size fractions significantly,with the highest increment （0.34 g·kg-1·a-1） in sand.Fallowing also increased the organic carbon associated with clay and silt significantly.Straw return to cropland only maintained the organic carbon content in different particle-size fractions,while long-term application of chemical fertilizers was not beneficial to the organic carbon increase in particle-size fractions.Coarse silt and coarse clay had the highest distribution rates of organic carbon （27.9% and 27.1%,respectively）,being the important fractions in sequestrating organic carbon.When manure was applied with chemical fertilizers,the organic carbon in sand was significantly increased by 119.4%,while that in fine silt and coarse clay was significantly decreased by 40.3% and 37.9%,respectively,which resulted in the increase in the ratio of particulate organic carbon content （WPOC） to mineral-associated organic carbon content （WMOC）,and improved soil carbon property.Long-term application of manure combined with chemical fertilizers was the best mode to increase the organic carbon content in particle-size fractions and improve the fertility of grey desert soil.