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【目的】研究经济林复合经营模式中,鸡的养殖密度对林下表层(0~20 cm)土壤微团聚体特征和土壤理化性质的影响,并探讨特征微团聚体组成比例(PCM,<0.02 mm/(≥0.02~0.25 mm))、<0.02 mm与≥0.02~2.00mm粒级含量的比值(RMD,<0.02 mm/(≥0.02~2.00 mm))和分形维数D与土壤理化性质之间的关系。【方法】以四川盆周低山丘陵区柑橘林地为对象,在试验区中建立20 m×20 m标准地各4块,设置3次重复,分别饲养鸡0、600、1 200和2 400只/hm~2,采用“S”形5点取样法分别采集0~20 cm土样,并测定土壤微团聚体组成、有机质、全氮、碱解氮、全磷、有效磷、全钾和速效钾含量及土壤物理性质。【结果】柑橘林下养鸡经济林的复合经营模式增加了土壤微团聚体大粒级(≥0.02~2.00 mm)颗粒含量,降低了小粒级(<0.02 mm)颗粒含量。随养鸡密度的增加,土壤PCM、RMD和D值均逐渐减小。不同养鸡密度的土壤PCM、RMD及D均与土壤含水量、非毛管孔隙、毛管孔隙、总孔隙、通气度以及土壤有机质、全氮、碱解氮、全磷、有效磷、全钾和速效钾等含量呈显著负相关(P<0.05),与土壤密度显著正相关。【结论】柑橘林下养鸡可促进土壤较小粒级的微团聚体向较大微团聚体的转化,能有效改善土壤微团聚体组成,降低土壤PCM、RMD和D;土壤PCM、RMD和D可作为评价林下养鸡生态系统土壤理化性质的一项重要综合性定量指标。
【Objective】 The objective of this study was to investigate the effects of stocking density on soil micro-aggregates and soil physico-chemical properties in understory (0-20 cm) / (≥0.02 ~ 0.25 mm)), the ratio of the grain size fraction (<0.02 mm / ≥0.02 ~ 2.00 mm) Relationship. 【Method】 Citrus forests in the hilly area of the basin of Sichuan Province were used as objects. Four plots of 20 m × 20 m were established in the experimental area. Three replicates were set up, with 0,600, 1 200 and 2 400 / hm ~ 2. Soil samples of 0 ~ 20 cm soil depth were collected using the “S” shape 5-point sampling method and the soil microaggregate composition, organic matter, total nitrogen, And available potassium content and soil physical properties. 【Result】 The results showed that the compound management mode of raising chickens under citrus groves increased the content of macro-aggregates (≥0.02 ~ 2.00 mm) and decreased the content of granules (<0.02 mm). With the increase of chicken density, the soil PCM, RMD and D values decreased gradually. Soil PCM, RMD and D in different chicken densities were related to soil water content, non-capillary porosity, capillary porosity, total porosity, air permeability and soil organic matter, total nitrogen, available nitrogen, total phosphorus, available phosphorus, Potassium and other contents were significantly negatively correlated (P <0.05), and soil density was significantly positively correlated. 【Conclusion】 It is concluded that raising chickens under citrus groves can promote the conversion of smaller fractions of soil aggregates to larger ones, and improve the composition of soil micro-aggregates, and lower soil PCM, RMD and D, soil PCM, RMD and D can be used as an important comprehensive quantitative index to evaluate the soil physical and chemical properties of chicken forest ecosystem.