不同耕作方式下草甸栗钙土燕麦田土壤微生物特征

河北坝上地区高寒半干旱的独特生态环境,土地沙化风蚀严重,作物产量低,土壤微生物的活动尚未有深入研究,尤其是人为干扰下的土壤微生物在作物生长季的动态变化。为了明确耕作方式对草甸栗钙土土壤微生物性状的影响特征,依托定位12a的免耕、深松、常规耕作田间试验基础,通过辅助设置12a免耕、深松后的翻耕处理,监测了燕麦田土壤微生物量碳、活跃微生物量和土壤呼吸速率等性状。结果表明,土壤微生物量碳与活跃微生物量围绕燕麦抽穗期为"W型"时序变化,长期免耕与深松下呈现0—10 cm表层土壤富集微生物量碳的空间分布特征。免耕与深松有利于提高0—10 cm土层土壤微生物量,多年免耕和深松后翻耕能使土层间土壤活跃微生物量差异减小。燕麦田土壤呼吸速率呈现"U型"时序变化,免耕0—10 cm土层呼吸速率具有较其他耕作方式更高的趋势。在燕麦生育期内,土壤呼吸商一直处于较低而平稳的水平,燕麦收获后进入土壤微生物的高活性期;0—10 cm土层翻耕与多年免耕与深松后的翻耕处理土壤呼吸商有高于免耕处理的趋势。翻耕对于促进冷凉区土壤库存养分的活化与适时供应具有重要作用。

Characteristics ofmicrobes in loamy meadow chestnut soil planted with naked oats using different tillage methods

The Bashang plateau in Hebei Province has a unique ecological environment: high altitude, low temperature, and a semiarid climate, where the arable land shows serious desertification, wind erosion, and low crop productivity. The actions of the soil microbes in this region, especially those in the arable land, during crop growth seasons are still unclear. In this study, we monitored the soil microbial carbon (C), active-microbe amounts, and the soil respiration rate in the field-planted naked oats according to a 12-year permanent-location tillage experiment. We tested the treatments "no tillage" (NT), subsoiling tillage with high stubble (PT), and conventional tillage with straw returning (CT), in order to determine the effects of tillage methods on microbial activities in the meadow chestnut soil. The results showed that the soil microbial biomass C and the active-microbe amount exhibited a change pattern of the "W shape" around the heading stage. After lengthy NT and PT treatments, the soil microbial biomass C in the 0-10 cm soil layer was enriched. The difference in the active microbial amounts among various soil layers between NT and PT was decreased after longer tillage treatments. The soil respiration rate in the field displayed a change pattern of the "U shape" during various tillage treatments. NT yielded higher values in the 0-10 cm soil layer than did PT and CT. Across the whole growth stage, the respiration quotient (qCO₂) in the soil was always low during all tillage treatments and significantly increased after the harvest. Nonetheless, in comparison with NC and PC, NT increased qCO₂ in the 0-10 cm soil layer. In addition, CT was confirmed to play an important role in activation of the soil nutrient stocks and in promotion of the release of available nutrients in the cold ecological region.