Fractal Features of Soil Aggregates and Distribution of Alkaline Hydrolytic Nitrogen in Different Types of Eucalyptus grandis Plantations
Understanding the fractal characteristics of soil aggregates and alkaline hydrolytic nitrogen contents in Eucalyptus grandis plantations in the hilly region of Sichuan Basin was necessary to know the impact of Eucalyptus grandis plantations on soil stability and soil nutrient in this region.In this study,soils covered by 3.5-year pure Eucalyptus grandis,Eucalyptus grandis + fruits and Eucalyptus grandis + grain crops modes were selected as research examples,while abandoned farmland was taken as the control.Fractal theory was used as analytical method to investigate the fractal characteristics of soil aggregates and distribution of alkaline hydrolytic nitrogen content influenced by soil aggregates.Results showed that contents of soil aggregates presented the trend of increase first and decrease later with the decrease of soil aggregate sizes,the soil aggregates with 2～5 mm size played an important role in soil structure.Soil fractal dimension followed the sequence of abandoned farmland＞ Eucalyptus grandis + grain crops＞ Eucalyptus grandis + fruits＞pure Eucalyptus grandis,while alkaline hydrolytic nitrogen contents in soil aggregates followed the trend of abandoned farmland＞ Eucalyptus grandis + grain crops ＞ Eucalyptus grandis + fruits ＞ pure Eucalyptus grandis.Both soil fractal value and the alkaline hydrolytic nitrogen content of Eucalyptus grandis plantations were lower compared with abandoned farmland,indicating that Eucalyptus grandis growth would contribute to control soil erosion and cause losses of soil nutrients and fertility.Content of alkaline hydrolytic nitrogen mainly concentrated in fine sand and gravel with diameters of ＜0.25 mm and 0.25～0.5 mm.Correlation analysis indicated that soil alkaline hydrolytic nitrogen contents had a negative correlation with those soils aggregates with 0.25～0.5 mm size,significantly positively correlated with those with 2～5 mm size.The study scientifically evaluated the impact of Eucalyptus grandis plantations on soil structure and nutrients,providing a reasonable management model for soil and water conservation and fertility maintenance in the hilly region of Sichuan Basin.
国家科技期刊平台
NSTL
万方数据
维普
