增温对农田土壤碳氮循环关键过程的影响

为研究模拟增温对农田土壤碳氮循环关键过程的影响,设置了包含增温和对照两个处理的随机区组试验.采用气压过程分离技术(BaPS)测定土壤CO2产生速率、硝化速率、反硝化速率,并测定了根生物量、水溶性有机碳(DOC)、亚硝酸根、硫酸根、硝酸根等指标.结果表明,在冬小麦-大豆轮作生长季,增温和对照处理的平均土壤CO2产生速率分别为(149.7±19.6)和(114.5±11.6) μg/(kg·h),增温和对照处理的平均土壤硝化速率分别为(563.6±119.56),(399.9±98.2)μg/(kg·h),增温和对照处理的平均土壤反硝化速率分别为(319.7±94.6), (216.2±44.7) μg/(kg·h).研究表明,无论是在冬小麦生长季还是在大豆生长季, 模拟增温均促进了土壤CO2产生速率,增温对大豆田土壤CO2产生速率的促进作用高于冬小麦田,并且这种促进作用主要体现在作物生长后期.模拟增温显著促进了冬小麦–大豆田的土壤硝化、反硝化速率,夏季增温对土壤硝化、反硝化速率的促进作用最明显.模拟增温对土壤中根生物量、DOC、亚硝酸根、硫酸根、硝酸根含量无显著影响.

Effects of simulated warming on the key processes of soil carbon and nitrogen cycling in a cropland

In order to investigate the effects of simulated warming on the key processes of soil carbon and nitrogen cycling in a cropland, a randomized block experiment including two treatments (simulated warming and control) was carried out. Soil CO2 production rates, nitrification, denitrification were determined by using a barometric process separation method. Root biomass, dissolved organic carbon (DOC), nitrite, sulfate and nitrate were also measured. Under the winter wheat-soybean rotation, seasonal mean CO2 production rates for simulated warming and control treatments were 149.7 and 114.5μg/(kg·h), respectively. Seasonal mean nitrification rates for simulated warming and control treatments were 563.6 and 399.9μg/(kg·h), respectively. Seasonal mean denitrification rates for simulated warming and control treatments were 319.7 and 216.2μg/(kg·h), respectively. The result indicated that during both winter wheat and soybean growth seasons, simulated warming significantly induced soil CO2 production. The impact of simulated warming on soil CO2 production rates was particularly obvious during the later growth period for both winter wheat and soybean. Simulated warming significantly increased soil nitrification and denitrification during the winter wheat-soybean rotation period; a more obvious effect can be found in summer. Simulated warming did not affect root biomass, DOC, nitrite, sulfate and nitrate content.