我国主要农耕区水稻土有机碳含量分布及影响因素研究

Distribution and influencing factors of paddy soil organic carbon content in China's major farming areas

水稻土是我国主要的耕作土壤之一,水稻土有机碳变化与全球气候变化息息相关,因此研究我国主要农耕区水稻土有机碳含量分布特征及影响因素具有重要的现实意义。本文基于全国多目标地球化学调查1∶250 000土壤数据库,以行政区划分析了水稻土有机碳分布规律,从土壤pH值、年均气温、年均降雨量、耕作方式等角度探讨了其对水稻土有机碳含量的影响,并且采用主成分分析和逐步多元回归模型进行了量化。结果表明:黑龙江松嫩平原水稻土有机碳平均含量最高,为15.1g.kg-1,海南岛和广东珠三角地区水稻土有机碳含量较低。水稻土pH值对有机碳含量的影响较小,但在弱碱性(7.5<pH≤8.5)时,pH值与有机碳含量呈显著负相关。黑龙江、吉林等高经纬度区域,受气温变化影响明显,根据线性回归模型推算,若年平均气温每升高0.1℃,水稻土有机碳含量将降低2.51g.kg-1。耕作方式和农田管理措施变化对土壤有机碳含量有一定影响。年均降雨量、年均气温和土壤pH值是土壤有机碳含量分异的主要驱动因子,其中年均气温的影响最显著。

Paddy soil is one of the major agricultural soils varies with the change of global climate, and therefore, in Ghina. lhe content ot organic carbon in pauuy bULl it is significant to clarify the distribution of organic carbon in paddy soil of Chinese major agricultural lands and its influence factors. In this research, the distribution of organic carbon in paddy soil of different administrative divisions were investigated based on a national multl-purpose geochemical survey （1：250000） soil database. Besides, the influence of soil pH, annual average air temperature, annual averageprecipitation, cultivating methods etc. on the content of organic carbon in paddy soil were discussed. Principal components analysis and stepwise multiple regression models were also used to detail these researches. The results indicate that the content of organic carbon in the paddy soil of Heilongjiang Songnen plain is the highest （15. 1 g/kg） and those of Guangdong Pearl River Delta and Hainan Island are less. The organic carbon in soil can be hardly affected by soil pH, however, content of organic carbon can be phenomenally influenced by soil pH in a negative way when the soil pH ranges from 7.5 to 8. 5. In some high latitude areas like Heilongjiang province and Jilin province, organic carbon in soil is significantly influenced by air temperature. The content of organic carbon in paddy soil reduces 2.51g/kg with the annual average air temperature increase of 0. 1 ℃ according to a linear regression model. Cultivating and land managements can influence the content of organic carbon in soil slightly. Among several major influence factors, like annual average precipitation, annual average air temperature and soil pH, the influence of annual average air temperature is the most important.