耕作措施对土壤水热特性和微生物生物量碳的影响

Effect of tillage and residue management on dynamic of soil microbial biomass carbon

通过山西寿阳设置的8a田间定位试验,比较了全量秸秆还田、免耕覆盖和常规耕作3种耕作措施下土壤含水量、温度及土壤微生物生物量碳变化。结果表明:免耕覆盖与全量还田处理显著提高土壤含水量,与常规耕作相比表层土壤体积含水量在玉米苗期、拔节期、灌浆期和成熟期分别高出18%、22%、29%、21%和3%、10%、12%、13%,具有保水保墒的作用。在苗期不同耕作措施对土壤温度的影响达到显著水平,5 cm处免耕覆盖、全量还田与常规耕作处理土壤温度依次为:18.12、18.76和19.44℃,免耕覆盖和全量还田处理平均温度比常规耕作分别低1.32℃和0.69℃。土壤微生物量碳在整个生育期动态变化是首先迅速上升在玉米生育高峰期(拔节期)达到最高峰,然后开始下降,成熟期趋于平缓。免耕覆盖与全量还田处理下玉米各生育期土壤表层微生物量碳显著高于常规耕作,在苗期、拔节期、灌浆期和成熟期分别比常规耕作高出70%、40%、85%和30%和10%、20%、15%和15%。土壤微生物量碳与土壤温度和土壤含水量相关和极相关。

The long-term impact of tillage and residue management on soil microbial biomass carbon and,soil moisture and temperature was studied in a cinnamon soil in northern China over the maize（Zea mays L.） growing season in monoculture.Soil microbial biomass,the active fraction of soil organic matter,plays a central role in the flow of C and N in ecosystems,responds rapidly to management practices,and serves as an index of soil fertility.This study was to investigate the effects of different tillage-residue practices on soil microbial biomass carbon dynamics of maize after seven years of conserved tillage practice.Treatments of conventional tillage（CT）,no tillage with straw mulch（NTSM）,and tillage with all straw return（ASRT） were considered,and a randomized complete block design was used to lay out the experimental plots.The results showed that conservation tillage practices（NTSM and ASRT） had a noticeable positive effect on soil moisture content.The NTSM and ASRT treatments increased the soil moisture content by 18%,22%,29%,21% and 3%,10%,12%,13% at four physiological stages of the maize（seeding stage,jointing stage,filling stage,and maturation stage）.However,soil temperature were decreased under NTSM and ASRT compared to CT at both depths,especially at 5-cm depths where significantly lower values were observed（18.12,18.76,and 19.44℃ under NTSM,ASRT,and CT treatment,respectively）.The dynamic of microbial biomass carbon in the whole growth period rapidly reaches a peak at the jointing stage and then begins to decline and tend to stabilize.Soil microbial biomass carbon was significantly higher with NTSM and ASRT than with CT in the arable soil layer at different stages.The values under NTSM and ASRT increased by 70%,40%,85%,30%,and 10%,20%,15%,15% at seeding stage,jointing stage,filling stage,and maturation stage,respectively.There is a positive correlation between soil microbial biomass carbon and soil moisture and soil temperature.