Study On The Cost-benefit Of Soil Reconstruction In Land Consolidation

Surface protection and soil reconstruction do not be included in conventional land consolidation. The means mostly used to level land is pushing higher and padding lower. Surface soil is the topsoil layer which is ripened by farming.About 20cm-50cm ply, surface soil has rich nutrient content and in it crop root is the densest.The structure of surface soil usually is granular, crumb or cloddy. Topsoil layer is crop tillage layer which is forming by long time farming and fertilizing.It plays an important role in crop growth. Protecting and making use of surface soil is the core link in the process of land consolidation, it affects the comprehensive benefit of soil after land consolidation. Soil after arranged in the land consolidation project without surface soil stripping and backfill may reach the level before after many years.This article selects the land consolidation projects which are provincial key such as Guodu and Xizhangzhuang in Tai'an to discuss the protection and use of surface soil in the process of land consolidation. The results of the discussion shows that:(1) Conventional land consolidation use the means that pushing higher and padding lower to level land. In the process, surface ripening soil is turned to bottom, raw soil at the bottom is turned to surface. Bulk density of surface is increasing, organic content is reducing, soil microbial activity is lowering, soil quality is declining after land consolidation due to the mix of surface ripening soil and raw soil at the bottom.Followed a year, output per mu of wheat and corn respectively decline 46.72kg and 59.69kg. The data in the second year is 28.02kg and 36.98kg.(2) According to some features,such as unconspicuous hypsographic feature, regular field blocks and large area in plain region, the author select two means which are stripping and backfilling method by dividing plots and the method of piling topsoil in the middle of land as the main means of soil reconstruction in plain region. On the other hand, hypsographic feature is larger, field blocks are irregular and area is small in hilly area, due to those, the author select dividing band by plots to strip and backfill, topsoil one by one down and topsoil replacement by progressive.(3) The author selected two field blocks A and B in study area, and took the means that the stripping and backfilling method by dividing plots and the method of dividing bands by plots, and calculated the cost of surface soil stripping and backfill. Field block A is used the method by dividing plots to stripe and backfill surface soil, and the cost is 129.79yuan per mu. The cost of field block B is 135.98yuan per mu through another the method of dividing bands by plots.(4) According to the agricultural planting habit in study area, the author selected wheat and corn to do experiment on the field A₁,A₂,A₃,B₁₁,B₂₁,B₃₁ during the year 2009-2010, that is wheat in winter and corn in summer. And the author selected annual average output per mu on the field C₁,C₂,C₃; W₁,W₂,W₃; D₁,D₂,D₃; W₃,W₄,W₅ as a comparison and got the following conclusion: The benefit that land consolidation by dividing plots increased than conventional land consolidation is 128.88yuan and 47.42yuan per mu in 2009 and 2010; the benefit that the land consolidation of dividing bands by plots increased than conventional land consolidation is 111.73yuan and 41.40yuan per mu .However, the cost of surface soil stripping and backfill basing on fields blocks 129.79yuan per mu and the cost of surface soil stripping and backfill basing on bands reverse deduction method is 135.98yuan per mu. Thus the increased cost because of surface soil stripping and backfill can be took back in two years.