稻田土壤还原性物质特征及与甲烷排放的关联性分析

以南方稻田土壤的定位试验为研究对象,选取其中的五种不同施肥(无肥、化肥、猪粪+化肥、鸡粪+化肥、稻草+化肥)处理,监测了水稻生长期间土壤活性还原性物质、活性有机还原性物质、亚铁(Fe2+)含量、土壤Eh值和甲烷(CH4)排放的动态变化,分析还原性物质与CH4排放的关系。结果表明,水稻生长前期稻田CH4排放通量、土壤活性还原性物质、活性有机还原性物质和Fe2+含量均较高,并随水稻生长呈逐渐下降的趋势;而土壤Eh在水稻整个生育期介于-238至118 mv之间,且为水稻生长前期低,后期高。施用有机肥后的土壤活性还原性物质和Fe2+含量比化肥处理平均分别增加了13%和11%,而土壤Eh值则低于无肥和化肥处理。相关分析表明,CH4排放通量与土壤中活性还原性物质、Fe2+均呈极显著正相关关系,而与土壤Eh呈极显著负相关关系。通过逐步回归分析进一步表明,土壤中Fe2+含量显著影响稻田CH4排放,控制稻田土壤中Fe2+含量有利于稻田CH4的减排。

The characteristic of reductive material in paddy soil and its relation to methane emission

A field experiment of paddy field in South China was conducted to monitor the dynamics of soil active reductive material, active organic reductive material, ferric iron (Fe2+), Eh value and their relationship with methane (CH4) emission. There are five fertilization treatments including no fertilizer, pig manure + chemical fertilizer, chicken manure + chemical fertilizer and rice straw + chemical fertilizer. The results showed that the CH4 flux emission, the soil active reductive material and Fe2+ content was high in the early stage of rice growth, and then decreased gradually following the rice growth. However, soil Eh value ranged from -233 mv to 118 mv, and was low in the early stage and high in the later stage of rice growth. Compared with the chemical fertilizer treatment, the treatments of organic fertilizer increased the contents of soil active reductive material and Fe2+ by 13% and 11%, respectively. But the soils Eh value under organic fertilizer treatments were lower than those under no fertilizer and chemical fertilizer treatments. The correlation analysis showed that there were notable positive correlations of CH4 flux with soil active reductive materials and Fe2+ content, while negative correlation with soil Eh value. Stepwise regression further indicated that soil Fe2+ content significantly influenced CH4 emission from paddy field. If we can control the Fe2+ content in paddy soil, it will be in favor of the mitigation of CH4 emission.