长期施肥红壤矿物颗粒结合有机碳储量及其固定速率

Change Characteristics of Organic Carbon Stocks and Sequestration Rate of Particle-size Fractions in Red Soil Under Long-term Fertilizations

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。

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.