长期施肥对农牧交错区农田肥力因子及作物产量的影响

Effects of long-term fertilization on farmland fertilities and crop yields in farming-pastoral ecotone

【目的】研究长期不同施肥对农牧交错带土壤酶活性、土壤化学性质及作物产量的影响,为旱作农田合理施肥和土壤培肥提供依据。【方法】长期定位试验位于内蒙古自治区农牧业科学院武川旱作试验站,始于2004年,种植制度为马铃薯-油菜-莜麦轮作,一年一熟制。试验设置8个处理:CK(不施肥)、N(氮肥)、NP(氮磷肥)、NK(氮钾肥)、PK(磷钾肥)、NPK(氮磷钾肥)、M(羊粪)和NPKM(氮磷钾肥配施羊粪),2021年种植作物为莜麦。调查了莜麦产量;采集各小区耕层(0—20 cm)土壤样品,分析磷酸酶(PA)、硫酸酯酶(SU)、β-葡糖苷酶(BG)、β-木糖苷酶(BX)、α-葡糖苷酶(AG)、β-纤维二糖苷酶(BCBH)、乙酰氨基葡萄糖苷酶(NAG)、亮氨酸氨基肽酶(LAP)和土壤有机质(SOM)、碱解氮(AN)、有效磷(AP)、速效钾(AK)、pH等指标。通过主成分分析和冗余分析,探讨土壤酶活性分布特征及其与土壤化学性质和产量的关系。【结果】连续18年不同施肥处理均显著提高了作物产量和肥料对产量的贡献率,莜麦产量由高到低为NPKM>NPK>NP≈M>NK>N>PK>CK,施肥处理分别比CK增产140.5%、108.7%、76.3%、71.1%、57.5%、48.2%和20.8%,肥料对产量的贡献率分别为58.4%、52.1%、43.3%、41.5%、36.4%、32.5%和17.0%。长期施肥不同程度地提高了土壤有机质和速效氮、磷、钾含量,提高幅度均以NPKM处理最高,分别是CK的5.35、2.29、10.07和4.89倍。长期施肥显著影响了土壤pH,除PK处理外,土壤pH均显著低于CK,NPKM和NPK处理的土壤pH又显著低于除NP和NK外的其他施肥处理。NPK和M处理显著提高了参与碳(AG、BG、BX和BCBH)、氮(LAP和NAG)、磷(PA)和硫(SU)循环的酶活性。二者配施后的NPKM处理进一步提升了酶活性,其AG、BG、BX和BCBH分别是CK的1.71、1.87、2.05和2.11倍,LAP和NAG分别是CK的1.97和2.24倍,PA是CK的2.24倍,SU是CK的3.11倍。土壤酶活性的变化主要由养分因子驱动,其中AN、SOM和AP是关键的决定因子,分别解释了酶活性变异的75.1%、5.7%和4.6%。【结论】在农牧交错带薯粮油轮作条件下,长期氮磷钾平衡施肥可增加莜麦产量,提高肥料对产量的贡献率,增加土壤养分含量和酶活性,降低pH。单施羊粪也有效提高了土壤养分含量和酶活性,但增产效果显著低于氮磷钾肥或氮磷肥,羊粪与氮磷钾肥配合提升作物产量和土壤质量的效果最佳,显著优于化肥和羊粪单独施用。

【Objectives】We studied the soil enzyme activities,nutrient contents and crop yield after 18 years consecutive different fertilizations,so as to provide a basis for rational fertilization and farmland cultivation in the farming-pastoral ecotone.【Methods】A long-term positioning experiment was carried out in Dryland Experimental Station,Academy of Agricultural and Forest Sciences,Inner Mongolia.The experiment started since 2004,the cropping system was potato-rapeseed-naked oats rotation,and one crop per year.The experiment was composed of eight treatments,including:CK(without fertilization),N(nitrogen fertilizer),NP(only N and P fertilizer),NK(only N and K fertilizer),PK(only P and K fertilizer),NPK(N,P and K fertilizer),M(sheep manure),and NPKM(NPK combined with sheep manure),all the three crops were under the same fertilizer input scheme,and the crop was naked oats in 2021.After harvest,naked oat yield was investigated.Soil sample was taken from the topsoil(0−20 cm)of each plot for the determination of phosphatase(PA),sulfatase(SU),β-glucosidase(BG),β-xylosidase(BX),α-glucosidase(AG),β-cellobiosidase(BCBH),N-acetyl-glucosaminidase(NAG),L-leucine aminopeptidase(LAP),and soil organic matter(SOM),alkali-hydrolyzed nitrogen(AN),available phosphorus(AP),readily available potassium(AK),and pH.Principal component analysis and redundancy analysis were used to explore the distribution characteristics of soil enzyme activities and their relationship with soil nutrients and yield.【Results】All the fertilizer treatments significantly increased the yield and the contribution rate of fertilizers to yield.The yield increment and fertilizer contribution rate were in the descent order of NPKM>NPK>NP≈M>NK>N>PK>CK,with the yield increment relative to CK of 140.5%,108.7%,76.3%,71.1%,57.5%,48.2%and 20.8%,respectively,and the fertilizer contribution rate of 58.4%,52.1%,43.3%,41.5%,36.4%,32.5%and 17.0%,respectively.Long term fertilization effectively increased soil organic matter and available N,P and K content in different degrees,decreased pH.NPKM treatment was recorded the highest increment in OM and AN,AP,and AK,which were 5.35,2.29,10.07 and 4.89 times of CK.NPK and NPKM treatment were recorded the lowest pH.Long-term fertilization significantly increased soil enzyme activities.Both NPK and M treatments significantly increased activities of AG,BG,BX and BCBH(involved in carbon cycling),LAP and NAG(involved in nitrogen cycling),and PA and SU.In NPKM treatment,all the tested soil enzyme activities were significantly improved than those in NPK and M treatments,and the activities of AG,BG,BX,BCBH,LAP,NAG,PA and SU were 1.71,1.87,2.05,2.11,1.97,2.24,2.24,and 3.11 times of those in CK.The soil AN,SOM and AP were the key factors causing the variation of soil enzyme activity,explaining 75.1%,5.7%and 4.6%of the variation of enzyme activity,respectively.【Conclusions】In the farming-pastoral ecotone under rotation of potato-rapeseed-naked oat,balanced NPK fertilization can increase crop yield and the contribution rate of fertilizer to yield,and enhance soil nutrient content and enzyme activity,reduce soil pH in the long run.Merely applying sheep manure can improve soil fertility as well,but cannot increase crop yield as effective as the NPK fertilization.The combination of NPK fertilizer and sheep manure exhibits promotion effect that is significantly better than the separate application of them.