长期少免耕对中国东北玉米农田土壤呼吸及碳氮变化的影响

在黑土区37年不同耕作模式定位试验田，采用原位法比较常规旋耕灭茬起垄（CT）、旋耕留高茬行间深松-少耕（RT）、免耕（NT）和深翻（PT）4种耕作模式土壤呼吸速率及其与土壤温度和湿度的关系，测定土壤总碳氮、无机氮，微生物碳氮的变化。结果表明，玉米生育期间土壤呼吸呈单峰变化，开花期达最大值，生长季平均呼吸速率依次为RT > NT > CT > PT。4个处理土壤温度与土壤呼吸速率间存在显著指数关系。不同耕作模式0~10 cm土壤温度可解释土壤呼吸速率变异的38.3%~67.9%，温度敏感性系数Q10范围为2.1~5.3；RT和NT处理显著提高0~20 cm土壤碳氮含量；RT处理在0~20 cm土壤中微生物碳含量均高于CT、NT和PT处理。RT处理土壤呼吸对温度响应提高，RT和NT处理显著增加上层土壤总碳氮含量，利于土壤质量提升。

Effects of Long-term Reduced and No-tillage on Soil Respiration, Carbon and Nitrogen Changes of Maize Farmland in Northeast China

In the current study, the conventional tillage(CT), high stubble row to row subsoiling-reduced tillage (RT), no-tillage(NT) and deep ploughing(PT) were compared by in-situ in the 37a tillage field experiment. The relationship between soil temperature and moisture, the change of soil total carbon and inorganic nitrogen, microbial carbon and nitrogen were analyzed. The results showed:the soil respiration in the field during the growth period of spring maize presented a mono-peak changes, and reached the maximum at the flowering period of maize. The average respiration rate in the growing season was RT > NT > CT > PT. There was a significant exponential relationship between soil temperature and soil respiration rate under different tillage modes, and the soil temperature at 0-10 cm could explain 38.3%-67.9% of soil respiration rate variation, and the range of Q10 is 2.1-5.3. The carbon content of NT and RT in 0-20 cm soil was significantly higher than that of other treatments, and the inorganic nitrogen content in different soil layers was significantly higher than that of CT and PT. Compared with other modes, RT has higher microbial carbon content in 0-20cm soil. RT improves the responsiveness of soil respiration to temperature. Long-term reduced tillage(RT) and no-tillage(NT) significantly increased the total soil carbon and soil nitrogen concentration in the upper soil layer, and what is contributing to improve soil quality in the black soil region.