摘要
为探究施肥模式对潮土区大豆生长季土壤有效氮供给的影响,本研究基于33年长期定位施肥试验,选取4种处理:不施肥(CK)、施氮磷钾化肥(NPK)、氮磷钾化肥+秸秆还田(SNPK)与氮磷钾化肥+有机肥(MNPK),测定分析大豆生长季内土壤铵态氮(NH4+-N)、硝态氮(NO3--N)、微生物量氮、可溶性有机氮含量的变化动态,以及参与土壤氮素转化的有机氮矿化酶活性、氨化作用强度与硝化潜势.结果表明,化肥与秸秆或有机肥配施可提高土壤全氮、有机碳、微生物量碳和可溶性有机碳含量,这对土壤脲酶、酰胺酶、蛋白酶和N-乙酰-β-D-葡萄糖苷酶活性及氨化作用强度和硝化潜势的提升有不同程度的促进作用.土壤NH4+-N含量与脲酶和蛋白酶活性呈极显著正相关,与酰胺酶活性呈显著正相关;NO3--N含量与氨化作用强度、硝化潜势呈极显著正相关.SNPK、MNPK处理下的土壤微生物量氮和可溶性有机氮含量均高于NPK、CK处理.潮土可溶性有机氮含量与大豆地上部氮素吸收呈极显著正相关,并最终影响大豆生长;成熟期SNPK、MNPK处理下的大豆地上部生物量均高于CK、NPK处理.综上所述,化肥与秸秆或有机肥配施可通过提高全氮、有机碳和活性有机碳含量正向调控土壤氮素转化微生物作用强度与酶活性,提高土壤有效氮供给能力,促进大豆生长.本试验结果可为潮土区合理施肥提供理论依据.
Abstract
This study was conducted to investigate the effect of different fertilization patterns on soil available nitrogen(N)supply during the soybean growing season in fluvo-aquic soil area.Based on a 33-year long-term fertilization experiment,four fertilization treatments were selected:no fertilization(CK),NPK fertilizer(NPK),NPK fertilizer combined with soybean/peanut straw(SNPK),and NPK fertilizer combined with organic fertilizer(MNPK),and the dynamic changes in soil ammonium N(NH4+-N),nitrate N(NO3--N),microbial biomass N(MBN),and dissolved organic N(DON)during the soybean growing season were analyzed.Additionally,organic N mineralizing enzyme activities,soil ammonification intensity,and potential nitrification rate,which involved in soil N transformation,were analyzed.The results showed that the SNPK or MNPK could increase the concentrations of soil total N,organic carbon(C),microbial biomass C,and dissolved organic C.The increases promoted the activities of urease,amidase,protease,N-acetyl-β-D-glucosidase,as well as the ammonification intensity and potential nitrification rate.Soil NH4+-N content was extremely significantly positively correlated with the activities of urease and protease,and significantly positively correlated with amidase activity.Meanwhile,soil NO3--N content showed an extremely significant positive correlation with ammonification intensity and potential nitrification rate.Higher levels of MBN and DON were observed under SNPK and MNPK treatments compared to NPK and CK treatments.There was a significant positive correlation between the dynamics of DON content and soybean shoot N uptake,and which ultimately affected the growth of soybean.At maturity,the aboveground biomass of soybean under SNPK and MNPK treatments was higher compared to CK and NPK treatments.In conclusion,SNPK or MNPK could positively regulate the intensity of soil N transformation microorganisms and enzyme activities by increasing the concentrations of soil total N,organic C and labile organic C.This,in turn,enhanced soil available N supply capacity and promoted the soybean growth.The results of this study provide a theoretical basis for rational fertilization practices in typical fluvo-aquic soil area.
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