Fractal Dimension of Coastal Soil Aggregates and Its Relationship with Physical and Chemical Soil Properties

Abstract

【Objective and objective】 Soil aggregate is a function unit commonly used to describe the impact of soil structure on soil fertility and quality. It is temporally dynamic, modulated by a myriad of biotic and abiotic factors such as wetting-drying cycles and root-induced activity. One method to characterize aggregate fraction is fractal dimension. This paper is to study the relationship between fractal dimension of aggregates and physical and chemical properties of coastal soil. 【Method】 Intact soil samples were taken from natural uncultivated land and rice fields at the Tiaozini reclamation area in Dongtai city, Jiangsu province. The fractions of water-stable aggregates in each sample were determined using wet-sieving, and fractal dimension of the soil aggregates under different cultivations was calculated by box-counting method. To elucidate the genesis of soil aggregation, we analyzed the correlation between fractal dimension and physical and chemical properties of the soils. 【Result】 Compared with the natural uncultivated land, planting rice increased soil macroaggregates by 4.21% and reduced fractal dimension of its aggregates by 0.03. Fractal dimension of the aggregates was negatively correlated with fraction of large aggregates, and negatively correlated with fraction of small aggregates. The mean weight and geometric diameters of the aggregates were negatively correlated with the fractal dimension. Factor analysis and correlation analysis both showed that the contents of Na+, Mg2+, Ca2+, K+, SAR and Cl- in the soil were positively correlated with the fractal dimension at significant level. 【Conclusion】 Planting rice increased the fraction of large aggregates and reduced fractal dimension of the aggregates of coastal soil, thereby improving soil structure. Fractal dimension of the aggregates was affected by contents of Na+, Mg2+, Ca2+, K+, SAR and Cl- in the soil at significant level.

Keywords

• coastal soil
• water-stable aggregates
• fractal dimension
• factor analysis