RESEARCH ON METHANE (CH4) AND NITROUS OXIDE (N2O) EMISSIONS FROM FOUR PADDY SOIL TYPES IN THE RED RIVER DELTA

Abstract

This study assessed the emissions of greenhouse gases (CH₄ and N₂O) in rice fields with 4 soil types (fluvisols, solonchaks, thionic fluvisols and acrisols). The results of the study show that CH₄ and N₂O emission dynamics on soils are very different according to the stages of growth and fertilization. The changes in CH₄ and N₂O emissions are different between soil types. Methane emissions in the season crop were higher than in the spring crop, ranging from 74.4 to 698.51 kg/ha/crop. Most of the N₂O emissions in spring crop are higher than in the season crop, ranging from 0.3 kg/ha/crop to 1.19 kg/ha/crop. CH₄ emissions in the spring crop usually start slowly and are low in the early period, then gradually increase into later growth stages, and are highest in the tillering, stalk development and decrease in the later stages to harvest, ranged from 3.12 to 14.67 mg CH₄ /m2/hour. CH₄ emissions tend to increase emissions immediately aftertransplanting and reach maximum rate in the period from tillering, then decrease to the end of the season, the average emission rate is from 2,74 - 20.36 mg CH₄/m2/hour. N₂O emissions in the spring crop are quite differentaccording to the growth stages and show a high dependence on nitrogen fertilization, the emission rate fluctuates in the range of 0.11 - 0.3 µg N₂O /m2/hour. The rate of N₂O emission in the season crop is lower than in the spring crop, ranging from 0.13 to 0.19 µg N₂O/m2/hour.