【摘要】 通过连续3年的野外调查与室内分析试验,研究了不同耕作方式(翻耕、旋耕、免耕)对玉米农田土壤养分及土壤微生物活性的影响。结果表明,不同耕作方式下土壤pH值略显酸性,土壤容重与土壤总孔隙度变化趋势相反;土壤容重基本表现为:免耕>翻耕>旋耕;土壤总孔隙度TSP基本表现为:翻耕>旋耕>免耕,不同耕作方式差异均显著(p<0.05)。不同耕作方式下土壤养分(有机碳、全氮含量)和有效养分(有效磷、铵态氮和硝态氮)均呈现出一致性规律,大致表现为翻耕>旋耕>免耕,不同耕作方式下土壤全磷含量差异均不显著(p>0.05);与免耕相比,土壤微生物量碳和氮、土壤微生物数量(细菌、真菌、放线菌、固氮菌和纤维素菌)均有明显的增加,大致表现为:翻耕>旋耕>免耕。土壤微生物活度的变化范围为0.38~0.69,依次表现为翻耕>旋耕>免耕,不同耕作方式下土壤微生物活度差异均显著(p<0.05)。不同耕作方式下土壤微生物量碳周转率高于氮周转率,说明微生物量碳更新比微生物量氮快,其中翻耕处理下土壤微生物量碳和氮更新较旋耕和免耕快。通径分析发现,不同土壤环境因子对土壤微生物活度产生直接和间接负作用,其中有机碳、全氮、硝态氮、铵态氮、细菌数量对土壤微生物活度产生直接效应;土壤微生物量碳、微生物量氮、真菌数量和固氮菌数量对土壤微生物活度产生间接效应。更多还原

【Abstract】 Soil nutrients and soil microbial biomass play an important role in material cycling and energy transformation in farmland ecosystem.We present a comprehensive analysis of soil nutrients and soil microbial activities of different tillage systems in farmland through three successive years’ field investigation and indoor analysis.The results showed that the soils of different tillage systems were slightly acidic,pH decreased in the order:no tillage>ploughed tillage>rotary tillage,and soil bulk density had the opposite trend compared with total soil porosity;soil organic matter and total nitrogen and available nutrients(available phosphorus,ammonium nitrogen and nitrate nitrogen)of different tillage systems had the same change trend,which decreased in the sequence:rotary tillage>ploughed tillage>no tillage,while contents of soil total phosphorus were no significantly different among different tillage systems(p>0.05);compared with no tillage,there were the significantly increases in soil microbial biomass(carbon and nitrogen),soil microbial quantites(bacteria,fungi,actinomycetes,nitrogen-fixing bacteria and cellulose bacteria),decreased in the order:rotary tillage>ploughed tillage>no tillage;soil microbial activities ranged from 0.41 to 0.69,which decreased in order:rotary tillage>ploughed tillage>no tillage with the difference significant(p<0.05).Overall,the soil microbial biomass carbon turnover rate was higher than the soil microbial biomass nitrogen turnover which indicated that the microbial biomass carbon updates faster than microbial biomass nitrogen.Path analysis showed that soil organic carbon,total nitrogen,nitrate,ammonium nitrogen and bacteria had the direct effect on soil microbial activity,and soil microbial biomass carbon,microbial biomass nitrogen,fungus quantity and nitrogen fixation bacteria had the indirect effect on soil microbial activity.更多还原