Soil Physical, Chemical And Biological Properties Of Saline-Alkali Paddy Field "Surface Dilution"

The western of Jilin Province's soil, which contains carbonate as main component and a lot of substitution of Na ions, is strongly alkaline due to its soil parent materials and low-lying terrain, strong evaporation, drought climate and so on. It is great harmful to the crops. Many researches indicate that it has good economic and ecological benefits to grow rice in saline-alkali land. Rice farming in saline-alkali land can improve the western area's cropping structure and greatly increase farmer's income. At the same time, consideres the effect on the ecological environment, Rice farming in saline-alkali land can improve soil physical and chemical properties in a relatively short period of time, increase vegetation coverage, prevent further desertification, directional fertilize soil and enhance the production and protection function of soil ecological system.This paper selects Jilin province Qianguo town Taohaotai village Jianbalahamlet and Hongguang farm in the Songnen southern plain as sampling site. Through the soil sampling and analysis, the soil physical and chemical properties, as well as microbial properties, are compared between the soil in abandoned grassland (comparing land) and the rice farming improved soil. We further clarify the "surface dilution" index system of quantitative criteria. The conclusions are as follows:(1) Both the soils in the improval rice farming land and the unimpoved soil have gleization characteristics and lime reaction. The accumulation of soil organic materials is less and Ap layer and P layer is thinner than that of the comparing land. While the soil depth of Ap layer and P layer is thicker in the improvement rice farming land, its thickness of humus layer increased 3-5cm, the soil in the humus layer is granular and below is prismatic structure.(2) There is sandy loam for the soil in the comparing land in the Ap layer and C layer, while there is sandy clay loam in the P layer. There are obvious changes in the percentage concentration of different soil particle size and soil texture for the rice farming soil. The sand content in each soil layers decreased, while silt and clay content were increased. All layers of the rice farming soil are sandy clay loams.(3) The water stable aggregate content for the rice farming soils with different years improvement is lower than the comparing land. For the paddy field with different year's improvement, the water stable aggregating content is highest in the soil with 15 years improvement, and increase 3.37% than the soil with 1 year improvement. Content of water stable aggregating increased with the number of years rice was first increased and then decreased. The water stable aggregate content was firstly increased followed by years rice farming improvement and then decreased. (4) There is no significant effect on soil quick-acting available nutrients for the rice farming soil, and there is irregular change in quick-acting available nutrients for different rice farming year's soil. Soil organic matter content of different rice farming year's soil is higher than the comparing land, and there are significant differences. The organic matter content as the rice growth period is significantly increased for 1-15 years improvement, and relatively slowly increases for more than 20 years, and decreases slowly after 40 years improvement.(5) The soil pH values were gradually decreased as the planting year evolution, the soil pH value is lower 2.08 after 40 years after planting. The soil pH value decreases greatly for 1-15 year, and slowly decreases after 20 years and preserve same after 40 years.(6) The soil salinity of P layer was higher than Ap and C layer in comparing land,1 year land and 5 year land. The soil salinity obviously decreases for 15 years rice farming improvement, so improvement's effect is more significant. The main composition of soluble salts contains sodium, potassium ions, as well as carbonate and bicarbonate, particularly bicarbonate has an absolute advantage. Comparing the soil in comparing land with that in the 1 year improvement, the highest ion content is in the surface, the distribution is a typical "T" type, which indicates that the soil is poor usability due to the serious salinization in the surface. The ion content is overall downward trend with the increase of years of improvement, and the distribution is inverted "T" type, which indicates that soil salinity and pH decrease as well as water and nutrient preserving capacity of soil gradually increased. The rice farming can validly inhibit the soda salt.(7) Rice planting also affects the amount of microorganisms; the amount of bacteria in soil improvement for 15 years reaches the highest value. The amount of fungi and actinomycetes in the soil improvement for about 10 years reaches the highest value.(8) The "surface dilution" of the characterization system and its standards are as follows:the soil rice planting improved for 10 to 15 years forms a "surface dilution", humus layer thickness is generally more than 15cm, and it is granular structure; soil chemical characteristics:pH value<8.5, the total soluble salt<0.2%, basicity<30%, organic matter content is 20g/kg or more; the soil soluble salt main compositions are K++Na+(mainly Na+) and HCO3- and CO32-, K++Na+<2cmol-kg-1,HCO3-< 1.7 cmol-kg-1,CO32-<0.5 cmol-kg"1.