添加玉米秸秆对黄棕壤有机质的激发效应

Priming Effect of Maize Straw Addition on Soil Organic Matter in Yellow-brown Soil

玉米秸秆还田是培肥地力的一项重要措施,但是玉米秸秆添加后会改变土壤原有有机质的矿化过程,即引起激发效应,从而影响土壤碳平衡和周转。因此,适量秸秆还田将是高效且环境友好的提升土壤生产潜力的关键。本试验以黄棕壤为研究对象,设不添加玉米秸秆对照(CK)和添加占干土重的1%、5%和9%的粉碎玉米秸秆处理进行室内培养,分析土壤CO2释放动态及激发效应。试验结果表明,添加不同量玉米秸秆后,土壤CO2释放速率和累积量呈现出抛物线型变化趋势。在培养前期,各处理土壤CO2释放速率表现为9%>5%>1%>CK,到培养的第8天左右,添加5%玉米秸秆的土壤CO2释放速率超过了添加9%玉米秸秆的土壤,在培养后期,所有处理的土壤CO2释放速率慢慢地趋于一致。从累积CO2释放量来看,添加5%玉米秸秆的处理比9%玉米秸秆的处理土壤总CO2释放量高,表明添加5%秸秆的处理对微生物群落和微生物活性的作用最大。在整个培养阶段,玉米秸秆添加对土壤有机质的激发效应均为负值,而加入的玉米秸秆并没有完全矿化,从而使土壤有机碳含量因添加玉米秸秆而升高。这些结果表明,添加玉米秸秆有利于提高黄棕壤土壤有机碳含量,在本试验的短期培养过程中以土壤干重9%的添加量增加最多。

Returning maize straws to soil is an important strategy to increase soil productivity, however, it can affect the mineralization process of soil organic matter (SOM), which is known as the priming effect, and then can further influence the turnover and stability of soil organic carbon (SOC). Thus, suitable maize straw addition is the key factor to improve soil potential productivity associated with high efficiency and friendly environment. In this study, an incubation was carried out to study the effects of maize straws at rates of 0(CK), 1%, 5% and 9% of dry soil on CO2 emission and priming effect of SOM. Results showed that the rate and accumulation of CO2 flux displaced parabolic curves with time across all treatments. At the early incubation, the rates of CO2 flux of all treatments were in an order of 9%>5%> 1 %>CK, but the rate of CO2 flux was higher in 5% treatment than in 9% treatment at the later incubation, and tended to be similar for all the treatments at the end. Higher accumulative CO2 emission in 5% treatment than in 9% treatment indicated that the community and activity of soil microbe were activated by maize straw addition. Negative priming effect with maize straws was observed during incubation, which might induce SOC accumulation. All these indicated that maize straws is beneficial to SOC in yellow-brown soil, with the adding rate of 9% of soil dry weight being better in this study.