施肥对玉米/大豆套作土壤活性有机碳组分及碳库管理指数的影响

Effect of fertilization on soil active organic carbon and carbon pool management index under maize/soybean intercropping condition

【目的】研究不同施肥模式对玉米/大豆套作下土壤有机碳组分和碳库管理指数的影响。【方法】通过长期定位田间试验,以不施肥(CK)作为对照,按照氮磷钾施用量相同原则,设单施化肥(NPK)、70%NPK+30%秸秆(J1)、70%NPK+30%牛粪(N1)、40%NPK+60%秸秆(J2)和40%NPK+60%牛粪(N2)施肥处理,测定土壤有机碳、可溶性有机碳、易氧化有机碳和微生物量碳含量,并计算土壤碳库管理指数。【结果】与CK相比,2013年N1、J2和N2处理显著地提高了土壤有机碳含量;2014年各施肥处理均显著地提高了土壤有机碳含量。除2013年NPK处理外,2013年和2014年各施肥处理土壤可溶性有机碳含量均显著高于CK,其中J2处理可溶性有机碳含量最高,2013年显著高于NPK。土壤易氧化有机碳含量在2年内均表现为N1、J2和N2处理显著高于CK,其中N2处理土壤易氧化有机碳含量最高。各施肥处理土壤微生物量碳含量均显著高于CK,其中N2处理土壤微生物量碳含量最高。与同年CK相比,各施肥处理均显著地提高了土壤碳库管理指数,其中N2处理土壤碳库管理指数最高。【结论】玉米/大豆套作下,40%化肥与60%牛粪配施(N2)是提高桂西北喀斯特地区土壤活性有机碳组分和碳库管理指数的最佳方案。

[ Objective ] Effects of different fertilizer applications on organic carbon fraction and carbon pool management index in soil were investigated under maize/soybean intercropping condition. [ Method ] Taking no fertilization （CK） as the control, five different fertilizing treatments, which were chemical ni- trogen ＋ phosphorus ＋ potassium fertilizers （NPK）, 70% NPK ＋ 30% straw （J1）, 70% NPK ＋ 30% cow dung （ N1 ）, 40% NPK ＋ 60% straw （ J2 ） and 40% NPK ＋ 60% cow clung （ N2 ） according to the same rates of N, P and K, were designed in a long-term field experiment. The contents of organic carbon, soluble organic carbon, readily organic carbon and microbial biomass carbon were measured, and soil carbon pool management index was calculated. [ Result] Compared to CK, soil organic carbon con- tents of N1, J2 and N2 treatments significantly increased in 2013, and the soil organic carbon contents of all fertilizing treatments significantly increased in 2014. Except for NPK treatment in 2013, the soil dis- solved organic carbon contents in 2013 and 2014 were significantly higher than that of CK. The dissolved organic carbon content of J2 treatment was the highest, which was significantly higher than that of NPK in 2013. The readily organic carbon contents of N1, J2 and N2 treatments were significantly higher than that of CK in 2013 and 2014, and the highest value appeared in N2 treatment. The microbial biomass carbon contents of all fertilizing treatments were significantly higher than that of CK, and the highest value ap- peared in N2 treatment. Compared with CK in the same year, the carbon pool management indexes of fer- tilizing treatments significantly increased, and the carbon pool management index of N2 treatment was the highest. [ Conclusion]The combined application of 40% NPK fertilizer and 60% cow dung is the optimal treatment for improving soil organic carbon fraction and carbon pool management index under maize/soy- bean intercropping condition in Karst area of northwest Guangxi.