Study On The Effects Of Soil Quanlity By Land Consolidation

Land is the material basis of existence and development for human. With the speeding up of industrialization and urbanization, the agriculture land is facing up the questions of quantity decreasing, quality declining and reserve resources lacking in the process of land using. In order to develop reserve resources, increase the area of cultivated land, improve the efficiency of land use, our country carries out land consolidation. Land consolidation is actually a process of soil reconstruction, after finishing land consolidation, the soil quality is bound to change. However, the soil quality which determines land productivity is neglected in present land consolidation. Therefore, land consolidation area in Sanba villiage of Fengdu county was choosen as a research object. Then, the research carried out a comparative anlysis on the soil quality in0-20cm,20-40cm and40～60cm layers before land consolidation and after finishing from the basic evaluation factors of soil physical-chemical and biological properties by adopting the combination of field sampling and laboratory analysis, to explore the influence of land consolidation on soil quality and provide gist for soil improving and fertilizer.This thesis included the following main conclusions:(1) Effects on soil physical properties by land consolidationIn the same soil layer, soil bulk density in each soil layer was reduced, and soil moisture content increased after finishing land consolidation. The effects of land consolidation on soil bulk density and moisture were reached significant level in the depth of40-60cm.In soil profiles, the percentage of soil medium sand was significantly decreased after finishing, and the percentage of other particle size particles was increased. In0-20cm soil layer after finishing land consolidation, the percentage of soil clay particle was significantly increased. In20～40cm soil layer, the percentage of soil medium sand was significantly decreased after finishing, and the percentage of coarse silt and coarse clay was significantly increased. In40～60cm soil layer, the percentage of soil medium sand was significantly decreased after finishing, and the percentage of coarse silt,medium silt,fine silt and coarse clay was significantly increased.The content of>0.25mm soil water-stable aggregates in soil profiles was increased by11.47%after finishing land consolidation, with2-1mm and1-0.5mm soil aggregates increased most. In the same soil layer, the content of>0.25mm soil water-stable aggregates was respectively increased by14.85%,14.85%,13.63%after finishing land consolidation, and the difference was significant in0-20cm and20-40cm soil layers.(2) Effects on soil chemical properties by land consolidationSoil pH and CEC of each soil layer were increased, and soil pH was changed significantly in0-20cm soil layer, the difference of soil CEC was extremely significant in the depth of20-40cm and40-60cm after finishing. The content of soil organic matter in each soil layer was decreased after fishing, and significantly decreased than before separately by49.95%,35.33%in0-20cm and20-40cm soil layers.The effect of land consolidation on the soil total nitrogen content was very significant. In0-20soil layer, the content of soil total nitrogen was decreased by25.78%,and respectively enhanced by40.00%,138.10%in20～40cm and40～60cm soil layers after finishing. The content of soil available nitrogen was changed significantly in20-40cm and40-60cm soil layers, and soil nitrogen content of each soil layer was down after finishing. The difference of soil total phosphorus, available phosphorus and total potassium in each soil lay available er before land consolidation and after was all significant. In0-20cm,20～40cm,40～60cm soil layers, the content of total phosphorus was separately decreased by35.89%,31.34%,29.69%, and available phosphorus was separately decreased by86.85%,84.76%,80.84%, and total potassium was separately decreased by32.84%,28.03%,23.42%. The content of soil available potassium was changed very signicantly in the depth of0-20cm and20～40cm, and separately decreased by35.04%and23.70%.(3) Effects on soil microorganism properties by land consolidationThe influence of land consolidation on the amount of soil bacteria in each soil layer was extremely significant. In0-20cm and20～40cm soil layers, the amount of soil bacteria were separately decreased by11.34%and15.58%, and increased by29.43%in40～60cm soil layer. The changes of soil fungi number were extremely significant level in0-20cm and40～60cm soil layers after finishing, and the amount of soil fungi were separately increased by25.54%and24.36%than before land consolidation. The amount of soil actinomycetes was changed very significantly in0-20cm and20-40cm soil layers, and separately decreased by65.85%,56.58%after finishing. It si visible that land consolidation had a highest influnced degreet on the amount of soil actinomycetes, but a relatively low degree on bacteria.On the whole, land consolidation reduced the content of soil microbial biomass carbon and nitrogen. The content of soil microbial biomass carbon was changed significantly in the soil layers of0-20cm and20～40cm, and separately reduced by13.91%,48.72%after finishing. The influence of land consolidation on soil microbial biomass nitrogen was significant in the depth of0-20cm.In soil profiles, land consolidation overall decreased the activities of soil urease and catalase, and improved the activities of soil intertase. The difference of soil urease, catalasea activities in0-20cm and20～40cm soil layers was all significance, the activities of soil intertase were changed significantly in each soil layer before land consolidation and after.(4) Effects on vertical distribution by land consolidationThe regularity of vertical distribution of soil bulk density, moisture content, microbial biomass carbon, invertase activities after finishing was in line with the regularity of before land consolidation. The regularity of vertical distribution of soil medium content in the soil particle composion is contrast to other size particles, and the content of each size particles had no significant difference among different layers. The regularity of vertical distribution of>0.25mm soil aggregate content after finishing was contrast to the regularity of before. The quantity of soil bacteria and fungi in0-20cm soil layer was all significantly higher than the quantity in20-40cm and40-60cm soil layers before land consolidation and after finishing. And the difference digree of soil actinomycetes number, microbial biomass nitrogen and jnvertase activities among different layers after finishing was all lower than the difference digree before land consolidation. The content of other soil quanlity indicators was all decreased with the increasing soil depth, and had no obvious difference among different soil layers after finishing.