砂姜黑土玉米秸秆有机碳的矿化特征

Characteristics of Organic Carbon Mineralization of Maize Straw in Lime Concretion Black Soil

【目的】探讨不同温度(10℃、20℃、30℃)、不同秸秆加入量(秸秆全量和过量)条件下,玉米秸秆还田对土壤有机碳矿化特征及其环境因子的响应机制。【方法】采用室内恒温控湿好气培养试验,对安徽淮北砂姜黑土在不同温度(10℃、20℃、30℃)条件下,设置50 g土样中加秸秆0.3 g(处理Ⅰ)、1.5 g(处理Ⅱ)、3.0 g(处理Ⅲ)及不加秸秆(CK)的处理,进行240 d的矿化培养。【结果】温度对有机碳矿化影响显著,在对照(CK)和秸秆加入量相同的处理中,有机碳的矿化累积量均随温度(10—30℃)升高而增加;温度较低(<20℃)时,CK、Ⅰ、Ⅱ、Ⅲ各处理的有机碳矿化温度系数(Q10)平均值约为1.229、1.251、1.572、1.399,温度较高(>20℃)时,CK、Ⅰ、Ⅱ、Ⅲ的Q10平均值约1.006、1.249、1.401、1.374,Q10值在温度较低时大于温度较高时,说明低温条件下,有机碳矿化速率对升温更敏感。同一温度条件下,不同处理秸秆加入量越大,有机碳矿化累积量越高,有机碳矿化的日变化量也越大。本试验中,一级动力学方程能较好地描述了不同处理土壤有机碳的矿化累积动态。土壤有机碳的潜在矿化量(C0)随温度变化不明显,在同一温度条件下,秸秆加入量越大,C0值越大。【结论】一级动力学方程能较好地描述不同处理土壤有机碳的矿化累积动态。不同温度、不同秸秆还田量及温度和秸秆还田量的交互作用,对玉米秸秆矿化过程中土壤有机碳含量的影响均达到显著水平。

[Objective] In order to better understand the characteristics of organic carbon mineralization of maize stalk in soil, the influences of different temperatures and different maize straw additions on the mineralization and decomposition of maize stalk in lime concretion black soil were investigated under the controlled condition in the laboratory. [ Method] Mineralization of maize stalk at different temperatures （10℃, 20℃, 30℃） and different levels of maize straw addition （0.3, 1.5 and 3.0 g straw at 50 g soil） were studied by aerobic incubation tests. [ Result ] Results showed that organic carbon mineralization of maize stalk in soil was significantly influenced by temperature. At the same maize straw addition level, the higher the mineralization temperature （from 10℃ to 30℃）, the higher the amounts of the organic carbon accumulated in soil. The mean mineralization temperature coefficients （Ql0） of soil organic carbon （SOC） were 1.229, 1.251, 1.572, 1.399 at lower temperatures （〈20℃）, and 1.006, 1.249, 1.401, 1.374 at higher temperatures （〉20℃） for CK, I , II and Ill treatments, respectively. The QloValues were higher at lower temperatures （〈 20℃） than that at higher temperatures （〉20℃）, which indicated that mineralization of SOC was more sensitive to temperature rise at lower temperature. The accumulation and daily mineralization of SOC were increased with the increasing of maize straw addition at the same incubation temperature. The dynamics of SOC mineralization could be well fit by the first-order kinetics equation, and the Co value increased with the increasing of straw addition. However, the potentially mineralized carbon （Co） was not significantly affected by temperature. [Conclusion] The increase of temperature and maize straw addition may be effective strategies for enhancing mineralization of maize straw in soil, and accelerating accumulation of organic carbon in soil.