耕作方式对紫色水稻土总有机碳及颗粒态有机碳的影响

Effects of Tillage Systems on Total Organic Carbon and Particulate Organic Carbon in a Purple Paddy Soil

为研究耕作方式对西南地区紫色水稻土总有机碳及颗粒态有机碳的影响,以1989年设立的位于西南大学农场的农业部重庆紫色土生态环境重点野外科学观测试验站内的长期免耕试验田为对象,研究在冬水田平作(DP)、水旱轮作(SH)、垄作免耕(LM)、厢作免耕(XM)和垄作翻耕(LF)5种不同耕作方式下,土壤中总有机碳(TOC)含量、颗粒态有机碳(POC)含量、颗粒态土壤质量分数和颗粒态有机碳分配比在土壤中的分布特点。结果表明,不同的耕作方式主要对表层土壤的TOC、POC分布产生显著影响,其中LM对提高积累TOC和POC贡献最大;0-60 cm土层TOC含量变化范围为7.10～34.45 g/kg,颗粒态土壤质量分数所占比例为30.38%～45.65%,POC含量为1.31～19.39 g/kg,各数值基本变化趋势都是随土壤深度的增加而减小。TOC与POC都可作为评价耕作方式影响紫色水稻土土壤质量变化与固碳能力的有效指标,但相同耕作制度下POC变化幅度更大,对其响应也更为敏感。从TOC和POC的关系来看,不同耕作制度下有机碳的增加与土壤物理保护能力的提高有关,免耕方式有利于有机碳以及颗粒态有机碳的保护和稳定。

To research the influence of different tillage systems on total organic carbon（TOC） and particulate organic carbon（POC） in a purple paddy soil from southwest China,in this paper we put the long-term no-tillage plots,which established since 1989 in the Key Field Station for Monitoring of Eco-environment of Purple Soil of the Ministry of Agriculture of China located in the farm of Southwest University（30°26′N,106°26′E） in Chongqing,as research object to discuss the distribution characteristic of TOC,mass fraction of particulate soil,the concentration of POC and POC distribution ratio in the soil under five tillage treatments including conventional tillage with rice only system（DP）,conventional tillage with rotation of rice and rape system（SH）,no-till and ridge culture with rotation of rice and rape system（LM）,no-till and plain culture with rotation of rice and rape system（XM） and tillage and ridge culture with rotation of rice and rape system（LF）.The results showed that different tillage systems had a significant impact on TOC and POC in the surface soil,and LM had the largest contribution to the accumulation of TOC and POC.The TOC ranged from 7.10 g/kg to 34.45 g/kg,the mass fraction of particulate soil ranged from 30.38% to 45.65%,the POC ranged from 1.31 g/kg to 19.39 g/kg under the 0-60 cm soil layer,the basic change trends of all the values were increased with the soil depth decreases.TOC and POC both could be acted as an effective evaluation index in reflecting the effect of tillage systems on the soil quality changes in purple paddy field and soil carbon sequestration capacity,but POC had the greater amplitude in the same tillage systems and a more sensitive response.From the point of view of the relationship between TOC and POC,the increase of organic carbon under different tillage systems had a relationship with the increase of ability to soil physical protection.No-tillage systems were the more helpful tillage in the protection and stabilization to TOC and POC in soil.