几种不同类型土壤有机碳库容大小及周转研究

通过土壤样品的室内培养,运用三库一级动力学理论,分析了沼泽土、草甸土、普通黄棕壤和棕色石灰土4种土壤有机碳库容大小、各碳库平均周转时间及分解动态。结果表明,4种土壤剖面表层和中层有机碳含量分别为8.48~24.53 g/kg,4.02~16.77 g/kg;活性碳占总有机碳含量的0.99%~5.01%,1.31%~1.91%,平均周转时间分别为8.8~14.3 d,10.4~16.5 d;缓效性碳占总有机碳含量的15.88%~59.04%,20.43%~48.36%,平均周转时间分别为1.3~29.1 a,3.6~21.3 a;惰性碳占总有机碳含量的39.97%~79.11%,50.31%~77.66%。不同类型土壤三库有机碳含量均是上层明显大于中层,培养3个月,表层和中层土壤有机碳累计分解量分别达到了165.99~2 429.57 mg/kg,108.04~743.02 mg/kg,4种土壤有机碳分解速率大小顺序:沼泽土>草甸土>棕色石灰土>普通黄棕壤,与活性碳的百分比含量成正相关关系。对培养期间土壤有机碳累计释放量进行拟合,发现三次方程(Y=b0 b1x b2x2 b3x3)能很好地描述其变化趋势,相关性均达到极显著水平(P<0.01)。

Study on Soil Organic Carbon Pool Sizes and Turnover in Some Soil Types

On the base of first order dynamic model,combining with a laboratory soil incubation experiment,the dynamics of soil organic carbon(SOC) decompositions,three carbon pool sizes and average turnover time are analyzed,including swamp soil,meadow soil,othic yellow brown soil and brown rendzina.The results show that these four soil types total soil organic carbon are 8.48~24.53 g/kg in the surface soil and 4.02~16.77 g/kg in the subsoil.The size of active SOC pool from surface and subsoil respectively accounts to 0.99%~5.01% and 1.31%~1.91% of total soil organic carbon,and the average turnover time is 8.8~14.3 days.Slow SOC pool,15.88%~59.04% and 20.43%~48.36%,1.3~29.1 years.Passive SOC pool,39.97%~79.11%,50.31%~77.66%.All the three pool sizes of those four soil types are more in the surface soil than subsoil.Cumulative emission of CO2 during incubation for 91 days is 165.99~2 429.57 mg/kg in the surface soil and 108.04~743.02 mg/kg in the sub soil.Decomposition rate order of these four soil types is swamp soil,meadow soil,brown rendzina and othic yellow brown soil,which direct interrelated with active SOC carbon percentage content.Curve fitting of SOC cumulative release amount during incubation showed that cubic equation can describe change trend,and the correlation has reached high significant level(P<0.01).