Methane emission from the System of Rice Intensification (SRI) in paddy field - 水稻强化栽培体系的CH_4排放特征

Abstract

Subtropical purple soil paddy region is a main ecosystem type in the hilly area of the central Sichuan basin. The system of rice intensification (SRI) is attracting more attention and being extended because of the gigantic potential of increasing yield. The objectives of this study were to obtain the carbon process of SRI in the ecological area and provide database for the methane emis-sion evaluation of the purple soil paddy region in China. The methane emission from the paddy rice was monitored through static chamber/gas-chromatography techniques in the hilly area of the central Sichuan basin. The results showed that,the daily variations of CH4 emissions were obvious in the full heading stage and the maturity stage,the shapes of the curves were the same type with a sin-gle peak and vale,CH4 emission rate was higher in the full heading stage than that in the maturity stage,in the two stages the maxi-mum CH4 emission peaks of daily variations all emerged in 15:00 PM with a higher air temperature,and the minimum emission peaks emerged during 7:00—9:00 AM with a lower air temperature. There were two CH4 emission peaks during rice growth stage,they presented to in the jointing stage and the harvest stage respectively. The 5 cm subsoil temperature and the air temperature influ-enced the CH4 emissions significantly. The total CH4 emission quantities of the conventional rice cultivation,the SRI with plastic film mulching and the SRI without plastic film mulching were 292.332,283.533 and 208.422 kg·hm-2 respectively in the whole growth stage of rice. Though the total CH4 emission quantities of the SRI decreased from 3.0% to 28.7% compared to that of the conventional rice cultivation,the yield of the SRI was not increased significantly compared to that of the conventional rice cultivation.紫色土稻作区是川中丘陵区的主要生态系统类型,而水稻强化栽培技术因其巨大的增产潜力而日益受到关注和推广,为了解这一生态区域稻田强化栽培体系的碳过程,同时为中国紫色土地区稻田CH4排放总量提供数据依据,利用静态箱/气相色谱法原位观测水稻(Oryza Sativa Linnaeu)强化栽培体系CH4排放通量特征。结果表明:齐穗期和成熟期稻田CH4排放存在明显的日变化,曲线均为单峰单谷型;齐穗期的CH4排放速率明显高于成熟期;日变化峰值均出现在一天中温度较高的15:00,最低值均出现在在温度偏低的7:00—9:00。稻田CH4排放通量的季节变化存在2个排放高峰,分别出现在生长最为旺盛的拔节孕穗期和收获前期。地下5cm温度和气温是影响CH4排放的重要因素。常规栽培、强化覆膜及强化无膜在水稻整个生长期内CH4排放总量分别为292.332,283.533和208.422kg·hm-2,强化栽培比常规栽培CH4排放总量减少了3.0%～28.7%,但增产效果不显著。