【作者】 汪可欣；

【导师】 王丽学；

【作者基本信息】 沈阳农业大学 ， 农业水土工程， 2009， 博士

【摘要】 保护性耕作技术是相对于传统耕作的一种新型耕作技术,起源于19世纪末的美国,通过对农田实行少耕、免耕技术,尽可能用农作物秸秆、残茬覆盖地表,以减少土壤水蚀、风蚀,从而提高土壤肥力和抗旱能力的先进耕作技术。目前广泛应用于各国旱作区农业生产,由于地域特征、气候因素及经济水平等方面存在不少差异,其适用规模和方式受到影响。因此,为进一步推广和应用保护性耕作技术,亟需研究其蓄水保墒增产机理。本论文针对东北地区旱作区农业用水不足的现状,结合辽宁省教育厅高等学校科学技术研究项目“保护性耕作条件下土壤水分运动规律的研究”(2004D207),研究保护性耕作技术的理论与应用问题。通过田间试验与理论分析相结合,分析不同覆盖措施抑蒸保水机理,研究玉米增产节水模式,建立适合免耕全覆盖、残茬覆盖及浅松覆盖等保护性耕作条件下的二维土壤水分运动模型,并在此基础上进一步分析各种覆盖方式对土壤水分动态变化过程的影响。研究成果能够对保护性耕作技术在东北地区应用和推广提供理论指导和决策依据。论文的主要研究内容与成果:(1)分析免耕全覆盖、残茬覆盖及浅松覆盖等保护性耕作模式对土壤蒸发影响,建立适应各自特点的表土相对蒸发强度与表层水分含量关系公式,R~2均大于0.75,可以作为保护性耕作条件下土壤水分运动数值模拟的上边界条件。(2)通过对不同覆盖措施土壤剖面水分的研究得出覆盖措施对提高地表以下0～10 cm土层水分效果显著,对深层影响不显著,且侧向补给优于裸土的结论。(3)运用土壤水动力学运动方程反求根系吸水率,同时分析玉米剖面取根资料,建立有效根密度分布函数,以此为依据结合土壤剖面水分分布建立了适合不同处理的二维根系吸水率模型。(4)建立保护性耕作条件下的二维土壤水分运动模型,该模型可适用于免耕全覆盖、残茬覆盖及浅松覆盖等耕作模式。采用交替方向隐式差分法进行数值求解,相对误差均在10%以内,达到理想效果,可用于保护性耕作条件下土壤水分运动规律的研究和土壤墒情的预测。(5)通过对土壤降雨入渗和雨后水分再分布过程的数值模拟再现田间土壤水分动态变化过程,分析表明:土壤水分发生显著变化的区域主要集中在0～40cm。降雨强度与耕作方式均对土壤水分运动有不同影响,揭示了不同覆盖处理土壤水分运动规律。(6)通过对不同覆盖措施下土壤墒情、土壤肥力、作物生长发育、产量以及水分生产效率等方面的对比研究,进一步明确适宜东北地区采用的保护性耕作模式。研究表明与传统耕作相比覆盖措施可提高春播期耕层水分6.69%～15.23%;生育期耕层水分1.51%～20.93%;水分利用效率6.36%～14.10%;当年产量4.23%～11.37%,两年产量9.46%～24.04%。休闲期覆盖可提高有机质、碱解氮和速效钾含量,但对速效磷与PH值有降低作用;生育期覆盖各养分指标均下降,但总体覆盖措施保持土壤肥力方面优于裸土。其中免耕全覆盖保水效果最佳,浅松覆盖保肥增产效果综合效益最优适宜东北旱作区推广。(7)针对东北地区区域特点,初步提出了适合东北旱作区的保护性耕作模式。本文研究创新点归纳如下:1)建立免耕全覆盖、残茬覆盖及浅松覆盖耕作模式下二维根系吸水速率模型。2)建立适用于免耕全覆盖、残茬覆盖及浅松覆盖耕作模式下二维土壤水分运动模型,可用于分析田间土壤水分动态变化过程。3)基于田间试验与理论分析,提出了适合东北地区应用和推广的保护性耕作措施。更多还原

【Abstract】 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.更多还原