天津土壤资源（Tianjin soil resources）.doc

天津土壤资源（Tianjin soil resources） Formation and distribution of soil types (a) soil is an important part of land resources, is the foundation of agricultural production, Tianjin City area is small, but affected by climate, topography, vegetation, soil and human factors, still form a variety of combinations of soil. In the northern, middle and lower mountains and hilly areas, the zonal soil cinnamon soil is formed under the combined effects of various factors. The vast plain area, flat terrain, underground water and soil under shallow groundwater frequent, meadow produce process, the formation of intrazonal soil is light meadow soil, fluvo aquic soil. In the low-lying, waterlogged, long-term or seasonal water depressions, the process of swamping caused by water damage, forming a hidden area of soil marsh soil. In the alluvial plain and the plain of the sea area, the groundwater with certain salinity can produce surface salt and form saline soil under the action of strong evaporation. In the alluvial plain area, coastal saline soil is formed because of shallow groundwater, high salinity and the influence of ocean tide. Tianjin city soil eluviation and deposition, clay, meadow, swamp, soil salinization and curing process, the formation of a variety of soil types, a total of 6 soil types and 17 sub types, 55 genera and 459 species of soil and soil. (two) soil type distribution 1. brown earth Distributed in the northern part of Jixian County, 700 meters and 900 meters above the mountains of the eight immortals table area, covering an area of 7.98 square kilometers, accounting for 0.07% of the citys total area. In the warm temperate semi humid climate, there are mosses and sedge growing in the coniferous and broad-leaved mixed forest in mountain area. Lin Zhongguang illumination is insufficient, the summer heat and damp, cold winter, litter slow decomposition, accumulation of organic matter. The precipitation storage nano thin soil fully leaching, reaction of lime, clay depo