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【目的】以四川盆周低山丘陵区柑橘林地为对象,研究不同养鸡密度对表层(0~20 cm)土壤微团聚体特征和土壤理化性质的影响,并探讨了特征微团聚体组成比例(PCM,<0.02 mm/(0.25~0.02 mm))、<0.02 mm与2~0.02 mm粒级含量的比值(RMD,<0.02 mm/(2~0.02 mm))和分形维数D与土壤理化性质之间的关系。【方法】在试验区中建立20 m×20 m标准地各4个,设置3次重复,分别饲养鸡0、600、1200和2400只/hm2,采用S型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水分物理性质。【结果】结果表明:柑橘林下养鸡增加了微团聚体大粒级(2~0.02 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均与自然含水量、非毛管孔隙、毛管孔隙、总孔隙、通气度、有机质、全氮、碱解氮、全磷、有效磷、全钾和速效钾呈显著负相关(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 different chicken densities on the characteristics of soil micro-aggregates and soil physical and chemical properties in the surface layer (0-20 cm) in citrus groves in the hilly areas around the basin of Sichuan Province. The effects of different micro-aggregates (PCM, <0.02 mm / (0.25-0.02 mm)), ratio of <0.02 mm to 2-0.02 mm fractions (RMD, <0.02 mm / (2-0.02 mm)) and fractal dimension D The nature of the relationship between. 【Method】 Four plots of 20 m × 20 m were established in the experimental area. Three replicates were set up, and 0,600,1200 and 2,400 / hm2 of chickens were raised respectively. S-type 5-point sampling method was used to collect 0-20 cm soil samples. The composition of soil micro-aggregates, organic matter, total nitrogen, available nitrogen, total phosphorus, available phosphorus, total potassium and available potassium and the physical properties of soil moisture were determined. 【Result】 The results showed that raising chickens under citrus groves increased the content of macro-aggregates (2-0.02 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. The soil PCM, RMD and D of different chicken densities were correlated with natural water content, non-capillary porosity, capillary porosity, total porosity, air permeability, organic matter, total nitrogen, total nitrogen, total phosphorus, available phosphorus, total potassium and available potassium (P <0.05), and positively correlated with soil density. 【Conclusion】 It is concluded that raising chickens under citrus groves can promote the transformation of smaller fractions of soil aggregates to larger ones, and improve the composition of soil micro-aggregates, reduce 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.