Dissertation > Agricultural Sciences > Agriculture as the foundation of science > Soil > Soil fertility (soil fertility )

Study on Aggregate Fractal Characteristics and Fertility of Purple Soil under Different Land-Use

Author LiZuo
Tutor HeBingHui
School Southwestern University
Course Soil and Water Conservation and Desertification Combating
Keywords Purple soil mother rock fractal dimensions soil aggregate soil fertility
CLC S158
Type Master's thesis
Year 2008
Downloads 226
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Soil is a self-similar structure of the porous medium, has a fractal characteristics, using the weight of soil particles can directly calculate the distribution of soil aggregates fractal dimension. Soil Aggregate structural conditions that affect the nature of the soil one of the important factors. Has a good reunion of the structure of the soil, not only has a high degree of the gap and water holding capacity, but also a good permeability. Soil Aggregate structure of soil nutrients is also the centre of fertility regulation, the size distribution and stability of the porosity of the soil, water holding capacity, permeability and corrosion resistance, especially at home and abroad in recent years on domestic soil clear Aggregates in an important role in soil fertility. How to quantify the aggregate characteristics of its soil fertility and the relationship between the soil must first reunion of quantitative description of the structure, the use of fractal model for the soil aggregates for the fractal dimension for research is one of the ways.In this study, to investigate the home of the purple soil in different land use under the reunion of fractal characteristics and the nature of physical and chemical characteristics of the purple soil in a different rock of the soil for the study, will be selected as a study area Feixianguan group, Shaximiao Formation, Suining group of three purple soil soil rock the region and in each region select a typical representation of five kinds of land use (woodlands, shrubs, natural grassland, agricultural land , Orchards), respectively, a cloth sampling, and through laboratory test analysis of their physical and chemical properties, the use of fractal dimension calculation formula purple soil aggregates distribution and fractal dimension, the composition of its aggregate and fractal characteristics Research, hope to explore different land use patterns on the rock formation of the purple soil and the soil micro-aggregate aggregate impact, and to look for the purple soil soil quality and structure of a quantitative description of the ways to improve the physical and chemical properties of soil, Fertilization provide the basis for guiding grip.The main research results:(1) Of different land use patterns on the purple soil reunion of fractal characteristics of the impact of research in the following conclusions: In the five kinds of land use, forest fractal dimension of the smallest and that its high content of the soil aggregates, and the forest coverage is relatively high, a large number of litters a year of return to the soil; natural grassland, shrubs Fractal dimension is also high, and a natural grass and shrub community structure complex, a multi-layer distribution, a large number of herbal undergrowth and litter, and other factors.Overall, woodland, shrubs and natural grassland soil aggregates 1-0.01 mm-high levels, orchards low, will be integrated with soil profiles from top to bottom to see woodland, the biggest changes in natural grassland, shrub land followed that woodland, shrubs Natural grassland and woodland soil micro-structure for the formation of a catalytic role.Land use different soil micro-aggregates of fractal dimension will have a greater change, which on the surface soil, and its basic trend of a reunion, and the surface soil can be precisely reflect the change in the human nature of the change in soil, Soil micro-aggregates of fractal dimension can also be characterized quality of the soil structure.Micro-reunion of the larger particle can show that the content of the soil micro-structure of the aggregate good or bad, the better the structure of its larger tablets of class-reunion of the higher levels, and the fractal dimension of the lower clay content of soil-the higher the aggregate The poorer the structure, performance for the fractal dimension higher.(2) The purple soil in different soil and rock the reunion of micro-aggregates fractal characteristics of the following conclusions:Soil fractal dimension is reflected soil structure geometry of the parameters in the performance dimension to the higher clay content, the higher the fractal dimension. Soil aggregate size distribution of the fractal dimension reflects the soil micro-aggregates and micro-aggregate content on the soil structure and stability of the trend, that is, aggregate size distribution of the fractal dimension of the smaller, with the soil Good structure and stability.The mother of three from the purple of the purple soil micro-aggregates are fractal dimension, red-brown-purple mud <Anzi mud <gray-brown-purple soil, the mother of Suining group of red-brown-purple mud always displayed the best soil Structure, analysis of its causes, in addition to their own soil physical and chemical firms, the main reason is that Suining Group mud-brown-purple areas for the comprehensive management, in particular its soil surface soil to improve the structure of comparison, the nature of the soil Also obviously improved.Purple mother of three of the purple soil regardless of the surface or subsurface, Shaximiao Formation gray-brown-purple marl mother of the structure of the soil aggregate fractal dimension basically show the smallest, with purple Shaximiao Formation sedimentary shale To compare the efficacy of the river environment related to the environment, Feixianguan Group dark purple marl deposition phase of high pressure hot dry under the shallow continental margin, Suining group of red-brown shale deposition for the drought conditions and relatively diffuse River flood in the lake To normal river environment, the mother of three different deposition phase, the difference caused by the deposition of the mother of mineral composition, chemical composition and physical activities of the different oxides, the mother of three purple of the purple soil showed different nature. Therefore, the development land, soil and water conservation in the course of the soil itself should not only attach importance to the characters, but also on home soil quality differences on the impact of soil and water conservation.(3) The purple soil in the different rock under different land use patterns of fertility conclusion of the study are as follows:Mother of different types of soil compared purple soil bulk density and total porosity, the greater bulk density of soil, the porosity of the smaller, more soil compaction, the impact of the stronger. During the short runoff in the process of erosion, soil bulk density is, the higher the level of soil compaction, soil particles were relatively difficult to loose soil erosion, handling, Suining group showed a stronger impact performance, its best performance of reunion . Suining group the largest density of the soil samples, the porosity of the smallest, most significantly for the performance of different types of purple soil of the mother of their physical and chemical properties of soil, regardless of the surface soil or deep soil, soil organic matter content and nitrogen, phosphorus and potassium content of the trend Basically the same, the soil fertility of the soil indicators are in Suining Group Numerical most notable.Comparing different types of land use from the soil bulk density and the porosity, whether it is soil or deep soil, with the bulk density porosity demonstrated by the size of the law is the same, the woodlands are the greatest density of the soil, the porosity Are the smallest of agricultural land are the smallest of the soil bulk density, the total porosity are the greatest. That is, the greater bulk density, porosity of the smaller. During the short runoff in the process of erosion, soil bulk density is, the higher the level of soil compaction, soil particles were relatively difficult to loose soil erosion, handling, Suining group showed a stronger impact performance, its best performance of reunion ; Different types of land use under the soil organic matter content and nitrogen, phosphorus and potassium content in the vertical direction declining. Various types of land use within the various layers of soil in addition to potassium, organic matter, nitrogen and potassium content to the natural grassland and woodland in the performance of most significantly, the natural grassland and woodland organic matter, nitrogen and phosphorus content all over, Is due to plant roots of native land, thereby reducing due to large rainfall caused by the loss of soil nutrients, and the porosity of the soil is also a smaller reduction one of the reasons for the loss of soil fertility. Agricultural land is due to human disturbance, loose soil, resulting in a massive loss of soil fertility.(4) The aggregate fractal dimension of the relationship between soil fertility and the conclusion of the study are: Fractal dimension can be better as the quantitative characteristics of the soil fertility indicators. In a certain range, the higher the fractal dimension, the clay content of soil in the rich soil of the chemical nature of the more lively. The absorption properties of soil, nitrogen content and content of organic matter with all the fractal dimension of the increases. The state of soil nutrients and soil particles are fractal dimension is very significant linear correlation between the soil particles that fractal dimension can objectively reflect the characteristics of the soil fertility.

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