(土娄)土区长期施肥农田土壤的可持续性评价

摘要

[目的]施肥是实现作物增产和土壤培肥的主要途径,综合评价长期不同施肥条件下农田土壤的可持续性,可为农田合理施肥和管理提供理论支撑. [方法]依托陕西杨凌"国家黄土肥力与肥料效益监测基地"长期肥料定位试验(23年),采集分析了该试验9个处理[不施肥(CK)、单施氮(N)、氮钾配合(NK)、磷钾配合(PK)、氮磷配合( NP)、氮磷钾配合( NPK)、氮磷钾配合秸秆还田( SNPK)、低量有机肥配合氮磷钾( M1 NPK)和高量有机肥配合氮磷钾( M2 NPK) ]的土壤养分、微生物特性及作物产量,计算了土壤养分指数、微生物指数、作物指数和可持续性指数,综合评价了长期不同施肥处理对(土娄)土区农田土壤可持续性的影响. [结果]CK和N处理土壤养分指数分别为0.75和0.87 ,两者之间差N显著( P<0.05 ) ,均低于土壤养分指数临界值1.00;其余处理的土壤养分指数在1.12 3.12之间,均大于临界值,其中NP和NK差N不显著,SNPK和PK差N不显著,其余各处理间均差N显著( P<0.05 ). CK、N、NK和PK处理土壤微生物指数在0.74 0.84之间,低于土壤微生物指数临界值1.00 ,其中CK和N差N不显著,NK和PK差N不显著,但两组之间差N显著( P<0.05 );NP、NPK、SNPK、M1 NPK和M2 NPK处理的在0.98 1.21之间,接近或大于临界值,其中M1 NPK和M2 NPK差N不显著,NP、NPK和SNPK差N不显著,两组之间差N显著( P<0.05 ). CK、N、NK和PK的作物指数在0.52 0.60之间,均低于作物指数临界值1.00 ,仅PK和N差N显著(P<0.05);氮磷配合的施肥处理(NP、NPK、SNPK、M1NPK和M2NPK)在0.98 1.02 之间,各处理间差N不显著,但均接近或大于临界值1.00. CK、N、NK和PK的可持续性指数分别为0.49、0.54、0.74和0.99 ,均低于可持续性指数临界值1.30 ,其中CK和N差N不显著;NP和NPK处理的可持续性指数分别为1.18和1.26 ,两者差N不显著,接近于可持续临界值;有机无机配合的处理( SNPK、M1 NPK和M2 NPK)的可持续性指数差N显著( P<0.05 ) ,分别为1.55、2.32和2.94 ,较临界值高19.5%、78.8%和126.3%. 土壤养分指数的变N性( 50.2%) 大于作物指数( 29.1%)和微生物指数( 18.4%) 的变N性,综合计算的可持续性指数的变N最高( 62.1%). [结论]冬小麦-夏玉米轮作条件下,长期不施肥和偏施化肥(土娄)土区农田生产不可持续,化肥平衡施用( NP和NPK)基本可持续,NPK化肥配合秸秆还田( SNPK)和适量有机无机配施( M1 NPK)是实现(土娄)土可持续利用的施肥模式.%[Objectives] Fertilization is one of the main approaches to increase crop yields and soil fertility . Assessment on the sustainability of farmland under long-term different fertilization modes will supply theoretical and practical supports for rational and sustainable fertilization in areas of Earth-Orthic Anthrosols .[Methods]Based ona long-term experiment of "National Monitoring Base of Soil Fertility and Fertilizer Efficiency on Loess Soil " in Yangling City, Shaanxi Province, samples were collected from the 9 treatment plots (CK, N, NK, PK, NP, NPK, SNPK, M1NPK and M2NPK), and totally 22 parameters were analyzed for the calculation of soil nutrient index (NI), microbial index (MI), crop index (CI) and sustainability index (SI), which were used to comprehensively assess the sustainability of the soil-crop system under different fertilization modes .[Results]1 ) The soil NI values in both the CK and N treatments were respective 0.75 and 0.87, lower than the threshold (1.00), and there was significant different between them ( P <0.05 ) .While those in other treatments were in range of 1.12-3.12 , higher than the threshold .The differences between NP and NK and between SNPK and PK were not significant , but significant among other treatments ( P<0.05 ) .2 ) The soil MI values in chemical fertilizer treatments ( CK, N, NK and PK) were all lower than the threshold (1.00) in range of 0.74-0.84 .The differences between NP and NK and between SNPK and PK were not significant , whereas significant between these two groups ( P<0.05 ) . The MI values in treatments containing NP ( NP, NPK, SNPK, M1 NPK and M2 NPK ) were in range of 0.98-1.21 , all close to or higher than the threshold 1.00 .The difference was not significant between M 1 NPK and M2NPK, nor between NP, NPK and SNPK, but significant between these 2 groups (P<0.05).3) The CI values in CK, N, NK and PK were in range of 0.52-0.60 , all lower than the threshold 1.00.Significant difference was only between N and PK ( P <0.05 ) .The CI values in treatments containing NP were in range of 0.98-1.02 , all close to or higher than the threshold , and there were not significant differences among them .4 ) The SI values in CK, N, NK and PK were 0.49, 0.54, 0.74 and 0.99 respectively, all lower than the threshold (1.30).The SI values in NP and NPK were respective 1.18 and 1.26 , close to the threshold , and there was no significant difference between the two treatments .The SI values in the combination treatments of chemical and organic fertilizers (SNPK, M1NPK and M2NPK) were respectively 1.55, 2.32 and 2.94, and were 19.5%, 78.8%and 126.3%higher than the threshold , and significantly different among them ( P<0.05 ) .5 ) The variability was 50.2%, 29.1%and 18.4%in NI, CI and MI.The variability SI, computed by NI, CI and MI, was 62.1%.[Conclusions] In winter wheat-summer maize rotation system , the soil fertility is unsustainable under long-term no fertilization or partial fertilization patterns , basically sustainable under balanced chemical fertilization ( NP and NPK) patterns, and the most sustainable under the chemical NPK fertilizer and straw return (SNPK), or manure (M1NPK) combination in areas of Eum-Orthic Anthrosols.