晋南县域农田生态系统土壤碳氮时空变化特征

气候变化背景下,对农田土壤有机碳和氮的研究是陆地生态系统碳、氮循环的热点之一。利用第2次山西省和县级土壤普查资料,通过野外调查、采样和分析不同土壤类型,探讨1980—2010年晋南农田土壤C,N的时空变化规律。结果表明,1980,2010年土壤有机碳的平均值分别为7.13,6.62 g/kg,全氮的平均值分别为0.70,1.01 g/kg,2个时期的C/N的平均值分别为10.19和7.12。30 a间,土壤有机碳、C/N都有所下降,而全氮含量有所增加,主要由于长期耕作和秸秆焚烧造成农田生态系统土壤有机碳的大量损失,使农田成为温室气体的一个排放源。近年来,通过推广免耕、秸秆还田、合理施肥等农田管理措施,促使农田土壤有机碳提高,并将其成为温室气体的吸收汇。

Spatial and Temporal Variability of Agro-ecosystem Soil Carbon and Nitrogen in Southern Shanxi

Study agro-ecosystem soil organic carbon(SOC) and nitrogen cycle is one of the hot topic in the land ecosystem under climate changing.Using data from the second Shanxi province and country soil survey,the paper studied agro-ecosystem soil carbon and nitrogen changing trend from 1980 to 2010 based on field investigation,sample collection and soil types analysis. The results indicated that the mean value of SOC were 7.13 g/kg and 6.62 g/kg,total nitrogen was 0.70 g/kg and 1.01 g/kg,C/N ratio 10.19 and 7.12 in 1980 and 2010,respectively.Soil SOC and C/N ratio decreased while nitrogen increased during 30 years. The longtime tillage and straw burning caused significant losses of SOC and made cropland an emission source of greenhouse gas. In recent years SOC in cropland has been increasing due to the spread of no-tillage techniques,and the increase of straw returning area,and rational fertilization.This could turn the cropland into an important sink of greenhouse gas.