红壤性水稻土有机无机复合体中碳氮特征对长期施肥的响应

Response of Carbon and Nitrogen Distribution in Organo-Mineral Complexes of Red Paddy Soil to Long-Term Fertilization

【目的】研究长期施肥对红壤性水稻土有机无机复合体中有机碳(OC)、全氮(TNOIC)特征的影响,为红壤性水稻土管理和培育土壤肥力提供依据。【方法】以长期定位施肥试验的红壤性水稻土为研究对象(始于1984年),选取CK(不施肥)、PK(施磷钾肥)、NPK(施氮磷钾肥)、NPKM(施70%氮磷钾肥+30%有机肥)4个处理。采集0—20 cm土层土样,分析各粒级(<2、2—10、10—20、20—50和50—250μm)有机无机复合体的分布,并探讨施肥对复合体中有机碳(OC)和全氮(TNOIC)含量、储量和碳氮比(C/N)的影响,以及有机无机复合体中OC和TNOIC对红壤性水稻土有机碳(SOC)、全氮(TN)贡献率的影响。【结果】与不施肥CK相比,施肥处理显著提高了20—50μm粒级复合体的比例,降低了<10μm粒级复合体比例,而NPKM处理与其他施肥处理相比,50—250μm粒级复合体的比例增加更显著;不同施肥对各粒级复合体中OC和TNOIC含量影响不同,与PK相比,NPK处理的50—250μm粒级复合体中OC和TNOIC分别增加了36.3%、80.6%;与NPK相比,NPKM处理的50—250μm粒级复合体中OC和TNOIC含量分别增加了35.4%、19.5%,OC和TNOIC主要分布在10—20μm粒级复合体中,施肥显著降低了<2μm粒级复合体OC和TNOIC储量,同时增加了20—50μm粒级复合体OC和TNOIC储量,与PK相比,NPK处理对<2和50—250μm粒级复合体OC储量分别增加了18.5%和31.2%,TNOIC储量分别增加了18.8%和73.7%,与NPK相比,NPKM处理对<2μm粒级复合体中OC和TNOIC储量分别降低了25.6%和27.4%,而50—250μm粒级复合体则分别提高了56.3%和38.6%;不同施肥处理显著影响50—250μm粒级复合体的C/N,与PK相比,NPK处理的50—250μm粒级复合体的C/N比降低了24.6%,与NPK相比,NPKM处理的50—250μm粒级复合体C/N比提高了13.4%;长期不同施肥显著影响各粒级有机无机复合体对土壤SOC、TN的贡献率,与PK相比,NPK处理50—250μm粒级复合体对SOC、TN贡献率分别提高了17.4%和47.4%。与NPK相比,NPKM处理50—250μm粒级复合体对SOC、TN贡献率分别提高了39.5%和32.8%。【结论】在红壤性水稻土中,长期施肥促使大粒级有机无机复合体形成;化肥中的氮投入显著提高50—250μm粒级复合体中OC、TNOIC含量和储量;有机无机肥配施有利于提高土壤有机碳含量,提高大粒级有机无机复合体比例,有助于保存施入的无机氮肥,是红壤性水稻土长期培肥管理的有效措施。

【Objective】The effects of long-term fertilization on the distribution of organic carbon(OC)and total nitrogen(TNOIC)of organo-mineral complexes in red paddy soil were studied,so as to provide a basis for long-term management and cultivation of soil fertility in red paddy soil.【Method】The red paddy soils in long-term fertilization experiment were studied(Since 1984),which included four treatments:no fertilization(CK),inorganic P and K fertilizers(PK),inorganic N,P and K fertilizers(NPK),and NPK plus manure(NPKM,70%NPK plus 30%manure).Soil samples of 0-20 cm soil layer were collected,and the distribution of organo-mineral complexes at each particle level(<2μm,2-10μm,10-20μm,20-50μm,and 50-250μm)was analyzed.The effects of fertilization on the content,storage of organic carbon and total nitrogen as well as the carbon-nitrogen ratio(C/N)were discussed.The effects of OC and TNOIC contents in organo-mineral complex on contribution rate of SOC and TN contents in red paddy soil were investigated too.【Result】Compared with the CK treatment,the fertilization treatment significantly increased the particle size ratio of 20-50μm and decreased the particle size ratio of<10μm.Compared with other fertilization treatments,NPKM treatment increased the proportion of 50-250μm grain size complex more significantly.Different fertilization treatments had different effects on the content of OC and TNOIC in grain size.Compared with PK,the content of OC and TNOIC in grain size from 50μm to 250μm under NPK treatment increased 36.3%and 80.6%,respectively.Compared with NPK,the content of OC and TNOIC in 50-250μm granular complex increased by 35.4%and 19.5%under NPKM treatment,respectively.The OC and TNOIC storage of the organic and inorganic complexes were mainly distributed at the 10-20μm particle level.And fertilization significantly reduced the storage of<2μm particle-level complex OC and TNOIC,but increased the storage of OC and TNOIC at 20-50μm particle-level.Compared with PK treatment,the OC storages of<2μm and 50-250μm particle-level complexes treated by NPK increased by 18.5%and 31.2%,respectively,and the storages of TNOIC increased by 18.8%and 73.7%,respectively.Compared with NPK,the NPKM treatment reduced the OC and TNOIC storages of the<2μm particle-level complex by 25.6%and 27.4%,respectively,while OC and TNOIC storages of 50-250μm particle-level complex increased by 56.3%and 38.6%,respectively.Fertilization significantly influenced the C/N ratio of 50-250μm particles.Compared with PK,the C/N ratio of 50-250μm fraction treated with NPK decreased by 24.6%;compared with NPK,the C/N ratio of 50-250μm fraction treated with NPKM was increased by 13.4%.Fertilization significantly affected the contribution rate of organo-mineral complexes of each particle size to SOC and TN content.Compared with PK,the contribution rate of NPK treatment 50-250μm particle-level complex to SOC and TN increased by 17.4%and 47.4%,respectively.Compared with NPK,the contribution rate of NPKM treatment 50-250μm particle to SOC and TN were reduced by 39.5%and 32.8%,respectively.【Conclusion】In red paddy soil,the long-term fertilization promoted the formation of large-grain organo-mineral complexes.The nitrogen input in the chemical fertilizers significantly increased the grain-level organic carbon,total nitrogen content and storage of the granular grade of 50-250μm.The organo-mineral combined application was conducive to increasing the soil organic carbon content and the proportion of large-grain organo-mineral complexes,which was helping to preserve the inorganic nitrogen fertilizer application. Therefore, organic and inorganic compound application was an effective measure for long-term fertilization management of red paddy soils.