滇中岩溶高原不同石漠化程度土壤团聚体养分及酶活性特征

Characteristics of nutrient and enzyme activity in soil aggregates of different rocky desertification levels in central Yunnan Plateau

【目的】探究岩溶石漠化区土壤团聚体养分及酶活性特征,可为该地区土壤改良和植被恢复提供理论依据。【方法】以滇中高原4种不同石漠化程度(潜在、轻度、中度和重度石漠化)土壤为研究对象,对其表层土壤3种团聚体(粒径<0.25 mm、粒径0.25~2.00 mm、粒径>2.00 mm)分布特征,团聚体4种水解酶(淀粉酶、脲酶、β-葡萄糖苷酶、酸性磷酸酶)活性和3种养分(有机碳、全氮、全磷)质量分数特征进行分析。【结果】①不同石漠化程度土壤团聚体组成比例随粒径的增大而增大,由高到低依次为粒径>2.00 mm(51.31%)、粒径0.25~2.00 mm(36.53%)、粒径<0.25 mm(12.04%)的团聚体。②不同团聚体土壤脲酶、β-葡萄糖苷酶、酸性磷酸酶、土壤酶活性几何平均数及有机碳、全氮质量分数均随粒径的增大而减小,对有机碳、全氮、全磷及酶活性的贡献率均为粒径>2.00 mm的团聚体最高,其次为粒径0.25~2.00 mm,粒径<0.25 mm的团聚体最低。③不同石漠化程度土壤团聚体淀粉酶活性均值为5.70 mg·g^(-1)·h^(-1),石漠化土壤的石漠化程度从大到小依次为潜在、轻度、重度、中度,石漠化土壤有机碳、全氮、脲酶和β-葡萄糖苷酶活性从大到小依次为重度、轻度、潜在、中度。团聚体粒径及石漠化程度均对土壤有机碳、全氮和酶活性有显著影响(P<0.05),但粒径和石漠化程度的交互作用对土壤养分及酶活性没有显著影响(P>0.05)。【结论】在岩溶石漠化地区,较大粒径的土壤团聚体在土壤组成上占优势,对土壤养分和酶活性的贡献率也相对较高,而较小粒径的土壤团聚体更有利于土壤养分和酶活性的积累,其相应的含量也更高。图2表6参45。

[Objective]With the features of the nutrient and enzyme activity of the soil aggregates in the rocky desertification area carefully investigated,this study is aimed to provide a theoretical basis for the soil improvement and vegetation recovery.[Method]With four kinds of soils with different degrees of rocky desertification(potential,mild,moderate and severe rocky desertification)in the Central Yunnan Plateau as the research objects,an analysis was conducted of the distribution characteristics of 3 aggregates(the particle sizes were<0.25,0.25-2.00,>2.00 mm respectively),the activity of 4 hydrolytic enzymes(amylase,urease,β-glucoside,acid phosphatase)and the content characteristics of 3 nutrients(organic carbon,total nitrogen,total phosphorus)in the aggregates.[Result](1)The proportion of aggregates in soil with different degrees of rocky desertification increased with the increase of particle size,from high to low:particle size was>2.00 mm(51.31%),particle size 0.25-2.00 mm(36.53%),particle size<0.25 mm(12.04%).(2)The geometric mean of soil urease,β-glucoside enzyme,acid phosphatase,soil enzyme activity and organic carbon and total nitrogen content of aggregates with different particle sizes all decreased with the increase of aggregate size.The contribution rate of different particle size aggregates to organic carbon,total nitrogen,total phosphorus and enzyme activity is the highest when particle size was>2.00 mm,which was followed by the particle size of 0.25-2.00 mm and the particle size of<0.25 mm in a successive pattern.(3)The mean amylase activity of aggregates with different degrees of stony desertification was 5.70 mg·g^(-1)·h^(-1),and the change trend for stony desertification soil was potential>mild>severe>moderate whereas the change trend of organic carbon,total nitrogen,urease and β-glucosidase activity for stony desertification soil was severe>mild>potential>moderate.The particle size of aggregates and the degree of rocky desertification had significant effects on soil organic carbon,total nitrogen and enzyme activity(P<0.05),but the interaction of particle size and degree of rocky desertification had no significant effect on soil nutrient and enzyme activity(P>0.05).[Conclusion]In karst rocky desertification areas,soil aggregates with larger particle sizes are dominant in soil composition and have a relatively higher contribution rate to soil nutrient and enzyme activity,while soil aggregates with smaller particle sizes are more conducive to the accumulation of soil nutrients and enzyme activity,with higher corresponding contents as well.[Ch,2 fig.6 tab.45 ref.]