温度和湿度对内蒙古草原土壤氮矿化的影响

Effects of temperature and moisture on nitrogen mineralization in Inner Mongolia grassland,China

本研究对内蒙古克氏针茅（Stipa krylovii）草原土样进行不同温湿度梯度下的室内培养试验, 温度梯度分别为9、14、22、30和40 ℃, 湿度梯度为13%、26%、39%、52%和66%体积含水量（Volumetric Water Content, VWC）。研究结果表明, 土壤氮矿化量和净氮矿化速率与培养温度均极显著相关（P〈0.01）;不同培养温度下, 土壤氮矿化量差异不显著（P〉0.05）;培养前期和中期不同温度下土壤净氮矿化速率差异显著（P〈0.05）。土壤氮矿化量和净氮矿化速率均值与湿度呈二项式关系, 52%~66% VWC内氮矿化量和矿化速率显著下降（P〈0.01）;除培养后期外, 其他时期不同湿度条件间, 净矿化速率差异均显著（P〈0.05）。温度和湿度对土壤氮矿化作用存在显著互作（P〈0.01）, 培养后期环境胁迫引起氮固持作用增强, 导致净氮矿化速率对温湿度的交互作用无显著响应。

In the present study, laboratory incubation with different temperature and moisture were conducted to imitate the effects of soil temperature and moisture on soil N mineralization using soil samples from Stipa krylovii grassland of Inner Mongolia, China. Five different temperatures （9, 14, 22, 30 and 40 ℃） and five different moisture （13%, 26%, 39%, 52%, 66% VWC ） levels were included with a full-factorial design. Results showed that soil mineral N production and net N mineralization rate were positively related to temperature （P〈0.01）. There was no significant difference between soil mineral N production under different temperature levels （P〉0.05）. There were significant difference between net N mineralization rate under different temperature levels during the early and middle stage of incubation （P〈0.05）. Both mineral N production and net N mineralization rate had a quadratic correlation with moisture because both of them decreased rapidly at 52%~66% VWC （P〈0.01）. The difference between moisture levels were significant for net N mineralization rate （P〈0.05） except the later incubation stage. There were significant effects of the interactions between soil temperature and moisture on nitrogen mineralization （P〈0.01）. Environmental stress in the late incubation stage improved nitrogen immobilization which resulted in that interactions between soil temperature and moisture had no significant effects on net N mineralization rate.