土壤化学特性、酶活性和产量对农业措施的敏感性研究

Study on the sensitivity of soil chemical properties,enzyme activities and yield to agricultural measures

【目的】研究不同农业管理措施(耕作强度、施肥、轮作)对土壤化学特性、酶活性及产量的影响,为选择适合的、对农业管理措施敏感的土壤质量评价指标提供依据。【方法】2019年5月在霍伊特维尔(OHHO,始于1963年),伍斯特(OHWO,始于1962年),亚当斯(ORAD,始于1992年)3个农业长期试验站分别采集了0—15 cm耕层土壤。在OHHO和OHWO试验站,分别在免耕(NT)、深耕(CT)、浅耕(MT)条件下设轮作(玉米–燕麦–苜蓿)、单作(玉米)处理;在ORAD试验站,分别在为NT、CT条件下,设不施肥、施肥(有、无覆盖物)处理。同年测定了土壤的pH、全氮、全碳、粘粒、砂粒、粉粒含量和β-葡萄糖苷酶、芳基硫酸酯酶、荧光素二乙酸酯活性。【结果】OHWO试验点不同处理间pH无显著差异。OHHO试验点玉米–燕麦–苜蓿轮作处理(COH)或玉米单作处理(CCC)与MT配合pH显著高于其他处理;ORAD试验点豆麦轮作、有覆盖物、施肥(PWY2),豆麦轮作、有覆盖物、不施肥(PWY)与NT配合(PWY2-NT、PWY-NT),及小麦–休闲的WFaNT与WFa-CT处理pH显著高于其他处理。耕作强度、作物轮作影响土壤pH,但pH没有一致的变化趋势,除PWY2-NT处理外施氮肥降低土壤pH。COH-NT、PWY2-NT、WFa2-NT处理全氮、全碳含量显著高于其他处理,说明轮作、免耕配合施肥显著提高土壤全氮、全碳含量;OHHO、OHWO试验点各处理间产量差异不显著,ORAD试验点产量的变化表明除了农业管理措施,产量还受病虫害或当季突发自然灾害的影响。3个试验点轮作配合免耕β-葡萄糖苷酶、芳基硫酸酯酶、荧光素二乙酸酯活性最高。在OHHO试验点β-葡萄糖苷酶可以区分轮作配合浅耕或深耕(COH-MT、COH-CT),单作配合免耕、浅耕、深耕(CCC-NT、CCC-MT、CCCCT)处理间的差异;在ORAD试验点可以区分豆麦轮作+覆盖物+施肥或不施肥分别配合免耕2个处理;区分麦–休闲+施肥或不施肥分别配合深耕2个处理间的差异,而全碳不能区分这些处理间的差异。β-葡萄糖苷酶与全氮、全碳、芳基硫酸酯酶相关性达5%或1%水平。【结论】对外来扰动的敏感性表现为β-葡萄糖苷酶活性>全碳>产量,以β-葡萄糖苷酶活性判断,免耕配合轮作是较为理想的提高土壤质量的农业管理措施。

【Objectives】The effects of different agricultural management measures(tillage intensity,fertilization,and crop rotation)on soil chemical properties,enzyme activities,and yield were studied to provide a basis for selecting suitable soil quality evaluation indicators that were sensitive to external disturbances.【Methods】In May 2019,0–15 cm soil samples were collected from three long-term agricultural experimental stations in OHHO(initiated in 1963),OHWO(initiated in 1962),and ORAD(initiated in 1992).The experimental design was no-tillage(NT),conventional tillage(CT),and minimum tillage(MT)combined with crop rotation(corn,oats,herbage)and monoculture cropping(corn)set up at OHHO and OHWO experimental stations.At the ORAD experimental station,the design was NT,CT combined with fertilization and no fertilization(with or without mulch),respectively.The pH,total nitrogen(TN),total carbon(TC),soil texture(clay,silt,and sand),β-glucosidase,arylsulfatase,and fluorescein diacetate activity of soil samples were measured in the same year.【Results】There was no significant difference in pH among the treatments at OHWO.The pH of OHHO rotation COH(or single-cropping CCC)combined with MT was(P<0.05)higher than other treatments.The pH of rotation,mulch,fertilization(or no fertilization)combined with NT(PWY2-NT,PWY-NT),and WFa-NT,WFa-CT was(P<0.05)significantly higher than other treatments at ORAD.Tillage and crop rotation affected soil pH,but there was no consistent change in the trend,and nitrogen fertilizer reduced soil pH except PWY2-NT treatment.Total nitrogen and carbon contents of COH-NT,PWY2-NT,and Wfa2-NT were significantly higher than other treatments,suggesting that rotation and no-tillage combined with fertilization significantly increased soil TN and TC content.The yield was not significantly different(P>0.05)among treatments at OHHO and OHWO sites.Besides the effect of agricultural management on yield,we found that the yield was also influenced by plant diseases,pests or unexpected seasonal occurrence of natural disasters.The highestβ-glucosidase,arylsulfatase,and fluorescein diacetate hydrolysis activities were observed under crop rotation with no-till at the three experimental sites.β-glucosidase exhibited variation among COH-MT,COH-CT,CCC-NT,CCC-MT,and CCC-CT.It also differed between PWY2-NT and PWY-NT,WFa2-CT and WFa-CT.However,TC was not different(P>0.05)among the treatments.The correlation betweenβ-glucosidase and TN,TC,arylsulfatase was 5%or 1%.【Conclusions】The evaluation indicators sensitivity to external disturbance is in the order ofβ-glucosidase activity>total carbon>yield.According to theβ-glucosidase activity,no-tillage combined with crop rotation is a satisfactory agricultural management measure to improve soil quality.