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Research On Soil Water Movement Of Conservation Tillage

Posted on:2010-04-13Degree:DoctorType:Dissertation
Country:ChinaCandidate:K X WangFull Text:PDF
GTID:1103360275495221Subject:Agricultural Soil and Water Engineering
Abstract/Summary:PDF Full Text Request
Conservation tillage technology originates from United States in the end of 19th century.It is advanced farming technology which through the implementation of reduced tillage, no-tillage technology, using crop stalks stubble ground cover to reduce soil water erosion, wind erosion, so as to enhance the capacity of soil fertility and drought-resistance .Function and role of conservation tillage technology have been proved by practice. Nevertheless, due to geographical characteristics, climatic factors and economic level there are many differences in the size and manner of its application be affected. Therefore, in order to further promote the wider use and application of straw mulch technology, the mechanism on moisture conservation ,distribution characteristics of fertility and the impact on crop yield an urgent need to study.In this paper,according to insufficient water for agricultural use of dry area for the Northeast ,and combined with the Liaoning Provincial Office of Education research project on "Conservation Tillage of soil water movement under the conditions " (2004D207), research on theory and application of conservation tillage technology. Combined with field experiments and theoretical analysis, analysis of restraint evaporation and water retaining mechanism, water-saving model of maize production,and establishment the two-dimensional model of soil water movement of no-tillage with full mulch,stubble mulch and surface tillage with mulch. On the basis of this ,further analysis of the coverage of soil moisture on the impact of the process of dynamic change.Results to the conservation tillage technology in the Northeast to promote the application and provide a theoretical basis for guidance and decision-making.The main contents and achievements are as follows:(1) Analysis of the effects on soil evaporation of conservation tillage such as no-tillage with mulch,stubble mulch and surface tillage with mulch ,and establishment the formula about surface soil moisture content and evaporation. the formula coefficient of determination are greater than 0.75, it can be used as conservation tillage conditions soil water movement under the numerical simulation of the up boundary conditions. (2) It is obvious that coverage of different measures have significant impact on the soil moisture of underground 0~10 cm, no significant effect on deep soil, and lateral recharge is superior to bare soil.(3) Based on the Equation of soil water dynamics in reverse calculation root water absorption, the same time analysis of corn root profile information , establishment of an effective root density distribution function,combined with the soil profile water content distribution establishment the two-dimensional model of root water absorption for different treatments.(4) Establishment the two-dimensional model of soil water movement of conservation tillage , the model could be applied to no-tillage with mulch,stubble mulch and surface tillage with mulch, Its partial derivative equation is solved by alternating direction implicit algorithm. The relative error of prediction value and actual value is less than±10%. The two-dimensional model of soil water movement can be used movement of soil moisture and soil moisture in the forecast for conservation tillage.(5) Appeared the dynamic changes of soil moisture of field process by the numerical simulation on rainfall infiltration through the soil and rain water redistribution.Analysis showed that, significant soil moisture changes occur mainly in the region 0~40cm.Rainfall intensity and tillage practices on soil water movement were different, reveals the movement of soil moisture effects of different cover.(6) Comparative study on different cover mode about soil moisture, soil fertility, crop growth, yield and water efficiency in the production, and further clarifying the appropriate the pattern of conservation tillage use for the northeastern region.Study shows that compared with traditional fanning ,the measures increase the coverage period of topsoil moisture in spring 6.69%~15.23%; reproductive period of topsoil moisture 1.51%~20.93%; water use efficiency of 6.36%~14.1%;year yield 4.23%~11.37%;two-year yield 9.46%~24.04%.Fallow periods can improve the coverage of organic matter, nitrogen and potassium content, but reduce the available phosphorus and PH value,reproductive period covered by the nutrient indicators are declining, but the overall coverage of measures to maintain soil fertility better than bare soil.No-tillage with mulch is the best measures of water saving, and surface tillage with mulch superiors to other on overall efficiency of fertilizer production security.So surface tillage with mulch is suitable for dry areas of Northeast.(7) According to characteristics for the Northeast region,suitable for dry areas of Northeast conservation tillage modeis also is proposed.The main innovation points of this paper are as followed:(1) Establishment the two-dimensional model of root water absorption for no-tillage with mulch,stubble mulch and surface tillage with mulch.(2) Eestablishment the two-dimensional model of soil water movement of no-tillage with mulch,stubble mulch and surface tillage with mulch,which can be applied to analysis of the process of soil moisture dynamic change in a field.(3) Experimental research and theoretical analysis,which kind of conservation tillage is suitable for application and extensive popularization for Northeast China is put forward.
Keywords/Search Tags:soil water movement, conservation tillage, numerical simulation, stubble-mulch
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