侵蚀程度对红壤团聚体分布及养分含量的影响

目的]探讨不同侵蚀程度下红壤团聚体和养分的变化规律,为侵蚀红壤的肥力提升和合理开发利用提供理论依据。方法]将红壤表层按照不同深度剥离来模拟不同土壤侵蚀程度,比较分析不同侵蚀程度下团聚体稳定性、有机质和各养分的变化规律及其相互关系。结果]各侵蚀程度红壤团聚体干筛粒级分布规律大体相似,以≥2mm粒级团聚体为优势粒级,与无明显侵蚀土壤相比,强烈侵蚀土壤≥2mm水稳性团聚体含量降低近1/3;随着土壤侵蚀程度增加,土壤碳、氮、磷等养分含量均表现出逐渐减少的规律,其中强烈侵蚀土壤有机质、全氮和全磷含量减少了30%左右,碱解氮含量减少了近50%,速效磷含量减少了80%以上。相关分析表明,土壤有机质、全氮、全磷、碱解氮含量均与≥2 mm团聚体含量、WSA,MWD和GMD值具有较好的正相关性(p0.05),与D和PAD值呈负相关。结论]不同侵蚀程度对红壤团聚体分布及养分含量有一定影响,可通过增加有机肥来改善侵蚀红壤结构,提高土壤肥力。

Effects of Soil Erosion Intensity on Aggregate Size Distribution and Nutrient Content in Red Soil Region

Objective] The objective of the paper is to study the variation of soil aggregate distribution,nutrient content and their correlation under different soil erosion intensities in red soil region,and provide the theoretical basis for improving the soil fertility and reasonable development and utilization of red soil.Methods] The tested soil was sampled from different layers below the surface to simulate the natural soil erosion of different intensities,and soil aggregate distribution,nutrient content and their correlation was investigated.Results] The aggregate size showed similar pattern in red soil with different erosion intensities,and was dominated by the aggregate size ≥2 mm.Compared to CK,≥2 mm water stable aggregate content decreased by 1/3.With the increase of erosion intensity,the contents of nutrients,including organic matter (OM),total nitrogen (TN),total phosphorus (TP),anailable nitrogen (AN),and available phosphorus (AP),aggregate mechanical stability and water stability decreased.The content of OM,TN and TP in severely eroded soil decreased by 30％,AP by 50％ and AN by 80％,respectively.Correlation analysis showed that the content of soil organic matter,TN,TP and AN significantly and positively correlated with ≥2 mm aggregate,＞0.25 mm aggregate(WSA),the mean weight diameter(MWD) and geometric mean diameter(GMD) (p＜0.05),whereas correlated negatively with aggregate fractal dimension(D) and percentage of aggregate disruption(PAD).Conclusion] The soil erosion intensity affects soil aggregate distribution and nutrient content,and the application of organic fertilizer in red soil plays an important role in improving soil structure and fertility.