环境因子对农业土壤有机碳分解的影响

为研究环境因子对有机C在农业土壤中分解的影响 ,在不同温度、水分及土壤质地下进行小麦和水稻秸秆及其根培养实验 ,结果表明 ,在同样的水热条件下 ,秸秆有机C的分解量大于根的分解量 .在温度较低情况下 ,升高温度促进了有机C的分解 ;而在温度较高的情况下 ,升高温度对有机C分解的促进作用降低 .在非淹水条件下 ,温度对有机C分解的影响随着时间的延长而逐步减小 .淹水条件下培养一周后 ,温度对有机C分解的影响不随时间而变化 .当含水量为 30 0 g·kg-1和 5 0 0 g·kg-1时 ,有机C分解较快 ,而在 2 0 0 g·kg-1和淹水条件下则分解较慢 ,空白对照培养结果的趋势是分解速率随水分含量的增加而加快 .培养实验的第一个月内 ,小麦秸秆有机C的分解量与土壤粘粒含量呈负相关

Influence of environmental factors on the decomposition of organic carbon in agricultural soils

To quantitatively investigate the effects of environmental factors on organic carbon decomposition, CO2-C was measured from the incubation of wheat and rice straw as well as their roots mixed with a paddy soil over a 90-day period. Results showed that decomposition of the straw carbon was faster than that of the roots. Amount of CO2-C released from the organic matter decomposition was quantitatively related to its properties of C/N ratio. Increase of temperature within a lower temperature range enhanced greatly the decomposition while such an enhancement weakened within a higher temperature range. Under the moist condition, the temperature coefficient of organic carbon decomposition declined exponentially with the incubation time. The temperature coefficient did not significantly decrease with the time for the submerged condition after one-week incubation. The effect of water status showed that the decomposition at the water contents of 300 g.kg-1 and 500 g.kg-1 was faster than that under the treatments of 200 g.kg-1 and the submerged. Within the first month period of incubation, carbon amount released from the incubation of wheat straw was negatively related to the clay fraction of the soils.