稻田土壤中甲烷产生率的实验研究

Experimental Study for Methane Production Rate in Rice Paddy Soil

本实验旨在研究稻田土壤中甲烷产生率对稻田CH_4排放的影响.观测结果表明:土壤各深度的甲烷产生率有很大的变化范围(1—4639ng·h^(-1)·g^(-1)d.w.).主要的甲烷产生区域是7—17cm深的土壤层,其中以13cm深的土壤层上的生成速率最大.土壤中甲烷产生率与稻田CH_4排放率在水稻生长的某些阶段有较好的相关性,但它的季节变化却不能与排放的季节变化完全耦合.在水稻生长期,土壤中甲烷产生率随时间而增大,并在8月份水稻收割前达到最大,其日平均值在38—767 ng·h^(-1)·g^(-1)d.w.间变动.稻田土壤中甲烷产生率也存在日变化,一般在下午达到最大值,但却没有发现它与土壤温度有明显的相关关系.在不同施肥及水稻品种的稻田土壤中也观测到不同的甲烷产生率.在土壤中产生的甲烷最多只有28.8％被排放到大气中,而其余多于71.2％的则被氧化在土壤中.

This experiment was conducted to study the influence of emthane production rate in paddy soil on CH4 emission from rice paddies. The measurement results show that, the methane production rates at different soil depths are in a very large range (1- 4639 ng · h-1 · g-1d.w). The main methane production area in soil is the layer of 7 - 17 cm below the surface, while the highest at 13 cm. Good correlation between CH4 emission and production rate in soil is found in a short period in the rice growing season, but the seasonal variation of CH4 production rate can not completely explain the CH4 emission variation in the whole vegetation period. During the rice growing season, methane production in soil increases with time and reaches a maximum ill August. The daily average of methane production rates varies from 38 to 767 ng · h-1· g-1d- w. diurnal variation of methanogenesis in paddy soil is also observed, normally with the highest value in the afternoon. But we cannot find obvious relationship between soil temperature and CH4 production rate. Different methane production rates are found in the paddy fields treated by different fertilizers and rice varieties. Of all the amount of methane produced in soil, only less than about 28.8% is emitted to the atmosphere while the other 71.2% or more is reoxided in soil.