保护性耕作对黄土旱塬玉米土壤呼吸及微生物数量的影响

研究了实施保护性耕作10年后秸秆还田和免耕对土壤可培养微生物数量和CO2释放的影响，采用LI COR 6400 09土壤气室连接红外线气体分析仪测定了玉米（Zea mays cv.Zhongdan No.2）土壤呼吸速率，采用平板涂抹计数法测定了根际土壤细菌、真菌和放线菌数量。结果表明，免耕和秸秆还田处理玉米花期土壤呼吸速率降低了8.3%和7.8%，玉米收获期土壤呼吸速率降低了15.5%和13.6%；土壤10 cm处地温与土壤呼吸速率变化趋势一致，且在传统耕作处理下最高；与传统耕作相比，免耕和秸秆还田不同程度地增加了根际土壤细菌、真菌和放线菌的数量，但各类微生物数量之间的比例恒定；土壤呼吸速率与3类根际土壤微生物的数量呈负相关，但不显著。可利用免耕和秸秆还田提高黄土旱塬土壤碳库贮量。

Effects of conservation tillage on soil respiration and microorganism amount in maize rhizosphere soil in Loess Plateau

The study was executed to analyze the influence of no tillage and residue retention on soil respiration and microorganism of maize rhizosphere soil in Qingyang Loess plateau after 10 years’ implementation of conservation tillage. Soil respiration was measured using LI COR 6400 09, soil Respiration Chamber completed with Infrared Gas Analyzer under 10 years conservation tillage, and microorganism amount of maize rhizosphere soil was measured by the method of dilution plate counting. The results showed that no tillage and residue retention significantly decreased the soil respiration rates of maize anthesis by 8.3% and 7.8% as well as harvesting period by 15.5% and 13.6%. The top 10 cm ground temperature and the soil respiration rates were the same and the top 10 cm ground temperature under traditional tillage treatment was the highest. The amount of bacteria, fungi and actinomycosis under no tillage and residue retention were higher than that in conventional tillage treatment and the ratio between three kinds microbe was not changed. Soil respiration rate had negative correlation with the amount of bacteria, fungi and actinomycosis, which was not significant (P>0.05). Many factors can influence the soil respiration rate, and the soil temperature was the main factor for soil respiration rate.