长期施肥对红壤水稻土水稳性团聚体有机碳、氮分布与储量的影响

 【目的】研究长期施用化肥以及化肥与稻草配合施用对红壤水稻土水稳性团聚体有机碳、氮分布与储量的影响。【方法】试验土壤采自湖南省望城无机有机肥长期定位试验田小区，各施肥处理为：CK（不施肥）、NP（施氮磷肥）、NPK（施氮磷钾肥）、NP+RS（施氮磷肥和稻草）和NPK+RS（施氮磷钾肥和稻草）。【结果】氮磷钾长期平衡施用和化肥与稻草长期配合施用有利于2～5 mm和0.5～2 mm水稳性团聚体含量增加。与CK处理相比，化肥与稻草长期配合施用处理能提高2～5 mm和0.5～2 mm水稳性团聚体内的有机碳含量和全氮、可矿化氮含量,同时也显著提高了二者在较大粒径（2～5 mm，0.5～2 mm）水稳性团聚体内有机碳、全氮和可矿化氮储量。与CK处理相比，NPK长期平衡施用的处理，也能提高大粒径水稳性团聚体（2～5 mm，0.5～2 mm）内的有机碳、全氮、可矿化氮的含量和储量，但提高的幅度小于化肥与稻草长期配合施用的处理。【结论】水稳性大团聚体对土壤有机碳、氮具有强富集和物理保护作用;化肥和稻草长期配合施用能显著提高大团聚体内有机碳、氮的含量和储量，是改善土壤团粒结构，提升红壤水稻土肥力的有效措施。2～5 mm和0.5～2 mm粒径团聚体是红壤水稻土有机碳、全氮和可矿化氮的主要载体。

Effects of Long-Term Fertilization on Distribution and Storage of Organic Carbon and Nitrogen in Water-Stable Aggregates of Red Paddy Soil

【Objective】 The effects of 25-year application of fertilizer and combining fertilizer with rice straw on water-stable aggregates size distribution and content and storage of aggregate-associated organic carbon and nitrogen were studied. 【Method】 The experiment was established in 1981 on a Typic Hapli-Stagnic Anthrosols. The treatments selected in this study were: CK: (without fertilization), NP(N,P fertilizers), NPK(N,P,K fertilizers), NP+RS(NP plus rice straw) and NPK+RS (NPK plus rice straw). 【Result】 Results showed that long-term application combining fertilizer with rice straw increased the content of water-stable aggregates in the 2-5 mm and 0.5-2 mm size fraction. Long-term application combining fertilizer with rice straw significantly increased the contents of organic carbon (OC), total nitrogen (TN) and potential mineralizable N (PMN) , and also increased the storages of OC, TN and PMN in these water-stable aggregates (2-5 mm, 0.5-2 mm). It was found in this study that balanced fertilization treatment with N, P and K fertilizers could increase the contents and storages of OC, TN and PMN in the water-stable macroaggregates (2-5 mm, 0.5-2 mm) compared with CK treatment, but the range of increase of OC, TN and PMN was lower in NPK treatment than in the treatments with combined application of fertilizer with the rice straw. Water-stable aggregate protected organic carbon and nitrogen were significantly greater for macroaggregates (2-5 mm and 0.5-2 mm) than for microaggregates (＜0.25 mm), indicating physical protection of organic carbon and nitrogen within macroaggregates. 【Conclusion】 Long-term application of fertilizer combined with rice straw increased significantly the contents and storages of OC, TN and PMN in water-stable macroaggregates(2-5 mm, 0.5-2 mm), which is an effective measure to improve soil structure, increase soil fertility in red paddy soil.