Li Ping, Wei Wei, Lang Man
Nanjing University of Information Science & Technology/Jiangsu Key Laboratory of Agricultural Meteorology, Nanjing 210044, China.
School of Applied Meteorology, Nanjing University of Information Science & Technology, Nanjing 210044, China.
Ying Yong Sheng Tai Xue Bao. 2022 Jan;33(1):59-66. doi: 10.13287/j.1001-9332.202201.022.
Soil water content is an important factor driving microbial activities related to soil nitrogen (N) transformation. In this study, N pair tracing technique combined with the numerical model FLUAZ was used to investigate the gross N mineralization, immobilization, nitrification, and denitrification rates in grassland and forest land soils from Beian City, Heilongjiang Province, China under laboratory condition [60% or 100% water holding capacity (WHC)]. The responses of soil gross N transformation rates to soil water content changes, and the mechanisms of N production, consumption, and conservation in soil under different water conditions and its environmental effects were elucidated. The results showed that changes of soil water content did not affect gross rates of N mineralization and NH immobilization in the forest land and grassland soils. Increasing soil water content from 60% WHC to 100% WHC significantly increased soil gross nitrification rate in forest land soil, but not affect that in grassland soil. Gross denitrification rates in grassland and forest land soils were close to zero under 60% WHC, and significantly increased under 100% WHC. The rate in grassland soil was significantly lower than that in forest land soil. In forest land soil, the ratio of gross nitrification to NH immobilization rates () and NO emissions under 100% WHC were significantly higher than that under 60% WHC. NO emission from grassland soil under 100% WHC was significantly higher than that under 60% WHC, but without significant difference in between the two water conditions. Our results indicated that increasing soil water content in the short-term may increase the negative environmental effects of nitrogen cycling in grassland and forest land soils, especially in forest land soil.
土壤含水量是驱动与土壤氮（N）转化相关的微生物活动的一个重要因素。在本研究中，采用N对示踪技术结合数值模型FLUAZ，在实验室条件下[60%或100%持水量（WHC）]，研究了中国黑龙江省北安市草地和林地土壤中的总氮矿化、固定、硝化和反硝化速率。阐明了土壤总氮转化速率对土壤含水量变化的响应，以及不同水分条件下土壤中氮的产生、消耗和保持机制及其环境效应。结果表明，土壤含水量的变化不影响林地和草地土壤中氮矿化和NH固定的总速率。将土壤含水量从60% WHC提高到100% WHC显著提高了林地土壤中的土壤总硝化速率，但对草地土壤没有影响。在60% WHC条件下，草地和林地土壤中的总反硝化速率接近零，在100% WHC条件下显著增加。草地土壤中的速率显著低于林地土壤中的速率。在林地土壤中，100% WHC条件下的总硝化与NH固定速率之比（）和NO排放显著高于60% WHC条件下。100% WHC条件下草地土壤的NO排放显著高于60% WHC条件下，但两种水分条件下的之间没有显著差异。我们的结果表明，短期内增加土壤含水量可能会增加草地和林地土壤中氮循环的负面环境影响，尤其是在林地土壤中。
