培养温度对水稻土有机碳矿化参数的影响研究

Effects of Incubation Temperature on Parameters of Organic Carbon Mineralization in Paddy Soils

采用室内培养法,对采自句容市华阳镇的水稻土进行5、15、25和35℃下的50 d培养实验,基于培养实验数据、6M HCl水解实验数据和三库一级动力学模型进行三库拟合,研究土壤有机碳矿化特征随培养温度的变化,并深入分析培养温度对Q10(土壤有机碳矿化温度敏感性系数)和三库拟合结果的影响。结果表明:(1)在5~35℃范围内,随培养温度升高水稻土有机碳矿化速率和累积矿化量均升高,15、25和35℃时土壤有机碳累积矿化量分别是5℃时的1.94倍、3.55倍、6.01倍。(2)培养温度的设定对三库拟合结果有较大影响,尤其是对活性碳库的影响,在不同培养温度下潴育、潜育、淹育水稻土活性碳的拟合值变异系数分别为64.9%、66.7%、48.5%。(3)Q10值变化范围在1.48~2.88,且随培养温度升高而降低、随培养时间增长而降低。Q10取2或者按照定义式测定的值对活性碳库和缓效性碳库拟合结果无影响,而对活性碳库和缓效性碳库平均驻留时间的拟合结果有影响。由此得出:利用在25℃下的培养结果估计的土壤有机碳库是存在一定误差的,应该进一步探索可行的三库拟合培养温度或寻找其他三库测定的方法;把Q10值取2代入三库一级动力学模型中对土壤有机碳进行三库拟合是可行的。

Paddy soils collected from Jurong were incubated using a modified laboratory incubation method at 5 ℃, 15 ℃,25 ℃ and 35 ℃, respectively. The incubation experiment lasted for 50 days. Passive organic carbon pool(Cp) was fractionated by the method of acid hydrolysis(6M HCl). Then active organic carbon pool(Ca), slow organic carbon pool(Cs), constants of organic carbon mineralization rate and mean residual time(MRT) were estimated on the base of three-pool first order model. Effect of incubation temperature on soil organic carbon mineralization characteristics, Q10(temperature sensitivity coefficient of soil organic carbon mineralization) and the results of estimation about the three carbon pools were studied. The results were as follows: 1 The soil organic carbon mineralization rate and the cumulative amount of mineralization increased significantly with the increase of incubation temperature ranging from 5 ℃ to 35 ℃.The cumulative amounts of organic carbon mineralization at 15 ℃, 25 ℃, 35 ℃ were 1.94 times, 3.55 times, 6.01 times of that at 5 ℃, respectively. 2 Incubation temperature had a great influence on the results of three carbon pool estimation, especially for the active carbon pool. The coefficients of variation for estimating active carbon pool size in three paddy soils incubated at different temperatures were 64.9%, 66.7% and 48.5%. 3 Q10 decreased with the increase of temperature and incubation time, varying in the range of 1.48 to 2.88. There was no effect on active carbon pool and slow carbon pool in terms of Q10 value by 2 or by a measured value, while there was a significant effect on MRT of active carbon pool(MRTa) and slow carbon pool(MRTs). Therefore, the results implied that a feasible incubation temperature or a feasible measuring method were needed to explore due to the uncertainty results about the estimation of three organic carbon pools. Additionaly, it was available to use the Q10 value by 2 to estimate three organic carbon pools based on the three-pool-first-order model.