玉米秸秆添加量对黄土高原旱作农田土壤固碳特征的影响

【目的】探明不同玉米秸秆添加量对农田土壤固碳特征的影响.【方法】在甘肃省定西市李家堡镇进行玉米田间定位试验,设0(无秸秆还田,CK)、40g/kg(低量秸秆,T3)、60g/kg(中量秸秆,T2)、80g/kg(高量秸秆,T1)4个玉米秸秆还田处理.采用尼龙网袋法对540d观测期内的土壤总有机碳(SOC)、活性有机碳(ROC)、微生物量碳(MBC)动态变化特征进行分析.【结果】从整体来看,不同秸秆添加水平下SOC含量呈连续降低趋势;ROC含量于90d达到峰值后逐渐降低;MBC含量于180d达到峰值后逐渐降低.较之CK处理,T1、T2、T3水平均可提升土壤碳素含量,且随秸秆添加量的增加而增加.T2水平下土壤碳库活度指数最大,为1.25,该水平下秸秆残留率最小.【结论】秸秆还田处理土壤碳库管理指数(CPMI)随秸秆施入量的增加而增加.因此,在0~80g/kg玉米秸秆添加范围内,60g/kg水平更有利于土壤碳素的固持及土壤质量的改善.

Effects of maize stubble addition level on ability of soil carbon sequestration of dry farmland of the loess plateau in central of Gansu

[Obj ective]To research the maize stubble addition on the ability of soil carbon sequestra-tion.[Method]A nylon mesh bags method was conducted in a maize field to study the effects of different maize stubble addition level (CK:0 g maize stubble+500 g soil,T3:20 g maize stubble+500 g soil,T2:30 g maize stubble+500 g soil,T1:40 g maize stubble+500 g soil)on the ability of soil carbon sequestration which involved the soil organic carbon (SOC)content,readily oxidizable organic carbon (ROC)content and microbial biomass carbon (MBC)content during all observation period (540 days)in dry farmland of the loess plateau in Central of Gansu.[Result]On the whole,the content of SOC of different maize stubble ad-dition levels showed a continuous decreasing trend,the content of ROC increased in 90 d,and reached the peak after gradually reduce.The content of MBC increased significantly in the early,and reached peak grad-ually decreased after 180 d.Under different maize stubble level compared to the treatment without stubble incorporation,the content of SOC,ROC and MBC increased of the content of maize stubble after 540 days.[Conclusion]The soil carbon pool management index of different maize stubble level increases compared with no stubble method and increases with the increase of the content.Within the extent of 0~80 g/kg of the content of maize stubble level,the residual rate of stubble is the smallest and the soil carbon pool ability index is the highest with the T2 (60 g/kg)level ,which shows that it is conducive to the improvement of soil quality and ability of soil carbon sequestration.