中文摘要：

采用物理分组方法分析了长期不同施肥模式下红壤耕层（0—20cm）不同大小矿物颗粒结合态有机碳储量差异及其固定速率。结果表明，与不施肥相比，长期施肥均显著增加了耕层土壤砂粒、粗粉粒、细粉粒及粗黏粒结合有机碳的储量，且以配施有机肥（M、NPKM和1．5NPKM）效果最显著，固碳速率分别达到0．13-0．24、0．19-0．23、0．05-0．16及0．12～0．36Mg·hm^-2．a^-1；施化肥（NPK、NP、N）和秸秆还田（NPKS）有利于增加细黏粒有机碳储量，且固碳速率高于配施有机肥，分别达到0．08～0．13和0．11Mg·hm^-2·a^-1。17a有机肥配施有利于增加固存于粗粉粒（30．5％）和粗黏粒（30．7％）中的有机碳；而秸秆还田（NPKS）和化肥施用下，有利于增加固存于粗粉粒（32．9％）和细黏粒（42．9％）中的有机碳，说明无论化肥配施还是有机无机配施，红壤粗粉粒是固定新增有机碳的主要组分，而长期配施有机肥是提升红壤各级颗粒有机碳库的较好施肥模式。

英文摘要：

The density fractionation scheme was used to study change characteristics of organic carbon stocks and sequestration rate of particle-size fractions in red soil under long-term fertilization. Our results showed that compared to non-fertilization （CK）, long-term fertilization significantly increased the organic carbon stock that combined with sand（ S ）, coarse silt（ CS ）, fine silt（ FS ）, and coarse clay（ CC ）. Especially, applications with manure（ M, NPKM, 1.5NPKM） showed highest carbon sequestration rate in S-OC（0.13-0.24 Mg·hm^-2·a^-1）, CS（0.19-0.23 Mg·hm^-2·a^-1 ）, FS （ 0.05-0.16 Mg·hm^-2·a^-1 ）, and CC （0.12-0.36 Mg·hm^-2·a^-1 ）, respectively. Applications of chemical fertilizers （ NPK, NP, N ） and straw incorporation were more effective to increase organic carbon in FC and the carbon sequestration rate were 0.08-0.13 and 0.11 Mg·hm^-2·a^-1 respectively, which were higher than the rates of applications with manure,. Applications with manure were apt to sequester more organic carbon in the CS（ 30.5% ） and CC （30.7%） particles. However, application of straw incorporation （NPKS） and chemical fertilizers sequenstered more organic carbon in CS（ 32.9% ） and FC（42.9% ） particles. Therefore, CS was the main carbon pool that sequestrated organic carbon in red soil under long-term fertilization. Moreover, long-term application with manure was helpful fertilization practices to increase Organic carbon in all particle-size fractions of red soil.