Fractal Dimensions Of Soil Aggregates And Distribution Of Carbon And Nitrogen From Different Environments In The Loess Plateau

According to both different types of vegetation and types of soil, we collected twenty-two soil samples from different regions of the Loess Plateau in order to investigate fractal dimensions of soil aggregates and discuss the distribution of the soil carbon and nitrogen in different kinds of soil aggregates and study the difference of mineralized nitrogen in different kinds of soil aggregates through Waterlogged Incubation. The main results are as follows:1. Fractal dimensions of soil aggregates and their relationship with important soil properties in different environments were studied. The results indicated that the fractal dimensions of soil aggregates ranged between 2.267~2.843 for the twenty-two soil samples. Regression analysis indicated that there was a highly significant negative correlation between fractal dimension and organic matter and total nitrogen. The correlation coefficient was -0.5919 for the relationship between fractal dimension and organic matter and -0.6407 for the relationship between fractal dimension and total nitrogen. In the soils that were classified as Los-Orthic Entisols, there was a significant correlation between the fractal dimension and the amount of material in each aggregate size class except for the >5mm aggregate size class. The boundary between positive and negative correlation was 0.25mm. Fractal dimensions were negatively correlated with the amount of aggregates with diameter >0.25mm and positively correlated with the amount of aggregates with diameter <0.25mm. Multivariate linear regression analysis indicated a significant partial correlation between the fractal dimension of soil aggregates and the amount of aggregates in the >5mm, 5-2mm, 2-1mm and 0.25-0mm size classes, while the partial correlation coefficient between the fractal dimension of soil aggregates and the amount of aggregates in the 1-0.25mm size class was not significant. These results indicate that the fractal features of soil aggregates provide a new means and a new scale for the description of soil fertility. At the same time it will lay a solid foundation...