外源氯化钙对土壤有机碳积累的影响

Effects of exogenous calcium chloride on soil organic carbon accumulation

[目的]本文旨在研究外源钙素对土壤中有机碳积累的影响。[方法]采用室内恒温模拟培养的方法,以连作10年的设施栽培土壤为研究对象,设置了不添加外源物质(CK)、添加氯化钙(T1)、添加水稻秸秆(T2)和同时添加氯化钙和水稻秸秆(T3)4个处理,对培养过程中土壤CO 2释放量及不同形态有机碳的含量进行了检测分析。[结果]添加外源氯化钙抑制了土壤中有机碳的矿化作用,CO 2累积释放量随培养时间呈下降趋势,与CK相比降幅由47.9%降到13.9%;随水稻秸秆的添加,氯化钙对有机碳矿化的抑制作用增强,但变化趋势相似,与单施水稻秸秆相比降幅由74.8%降到58.1%。添加外源氯化钙增加了土壤中总有机碳、可溶性有机碳和腐殖酸(胡敏酸、富里酸)的含量,在培养第24周,与CK相比增幅分别为9.2%、19.5%、44.3%和101.2%。但降低了微生物量碳,在培养24周降幅为13.3%。外源钙对总有机碳和可溶性有机碳的影响随新源有机碳的加入而增强,与单施水稻秸秆相比,在培养第24周增幅分别为29.2%和41.0%。[结论]添加外源氯化钙有利于土壤中有机碳的积累。

[Objective]The present research was aimed to investigate the impact of the incorporation of exogenous calcium chloride into the soil on the soil organic carbon accumulation.[Methods]The experiments were carried out under laboratory condition at constant temperature.Soil which has been used for continuous cropping system for 10 years in the greenhouse was selected as study material.Soil without adding exogenous substances was served as control group(CK),and other three treatments were calcium chloride incorporation(T1),rice straw incorporation(T2),and both calcium chloride and rice straw incorporation(T3).All soil samples were kept in the incubator with temperate at 25℃and relative humidity at 60%.Mineralization of soil organic carbon and the content of different forms of organic carbon in soil were measured at certain time intervals.[Results]Adding exogenous calcium chloride into the soil inhibited the mineralization of soil organic carbon,which induced a lower amount of CO 2 being released in T1 treatment.The decreased amount of CO 2 in T1 was greater than that of CK at the earlier time,but the difference was getting smaller with the time passing from 47.92%to 13.85%;To the contrary,adding rice straw significantly increased the amount of released CO 2 in the soil.However the inhibiting effect of exogenous calcium chloride strengthened with the addition of new carbon rice straw.Compared to the single application of rice straw(T2),the percentage of decreased CO 2 amount in T3 treatment was lowered from 74.84%to 58.12%with the time passing,but still higher than CK during all experimental process.Incorporation of exogenous calcium chloride in both T1 and T3 increased the content of total organic carbon,soluble organic carbon,humic acid,and fulvic acid in soil by 9.2%,19.5%,44.3%,and 101.2%,respectively in the 24 th week of the experiment,while the content of the microbial biomass carbon was decreased by 13.3%.Adding exogenous calcium positively impactedthe contents of total organic carbon and soluble organic carbon with the adding of new organic carbon,and the growth rate was enhanced by 29.2%and 41.0%,respectively compared to the single application of ricestraw in 24 th week of the experiment.[Conclusion]Adding exogenous calcium chloride was beneficial to the accumulation of organic carbon in soil.