【作者】 尹娟；

【导师】 费良军；

【作者基本信息】 西安理工大学 ， 水文学及水资源， 2008， 博士

【摘要】 在查阅国内外大量相关文献资料的基础上,结合我国农田灌溉和施肥特点,采用室内试验和理论分析相结合,以试验为主的技术路线,主要研究了施肥条件下波涌灌间歇入渗土壤水、氮运移和水肥耦合特性及其对地下水硝态氮浓度的影响,为提高水肥利用率、减缓地下水的NO₃^--N污染提供理论依据,研究具有重要的理论价值和生产实际意义。主要研究成果为:（1）研究了不同地下水位条件下均质土壤上升毛管水运动特性。随着土壤初始含水率的增大,毛管水上升速度增大;毛管水上升高度随时间的延长而增加,但毛管水上升速度随时间的延长而减小;初始含水率越大,达到相同高度所用的时间越短;建立了均质土壤毛管水上升高度与上渗时间之间的幂函数关系;土壤初始含水率越小,土壤水分达到平衡时所需的地下水补给量越大,且达到稳定所需的时间越长;揭示了地下水补给量与上渗时间之间的幂函数关系,毛管水上升高度与地下水补给量之间呈明显的线性函数关系。（2）研究了肥液连续入渗和波涌灌间歇入渗能力、湿润锋运移、土壤含水率分布、土壤NO₃^--N运移特性及地下水NO₃^--N浓度的分布特性。与连续入渗相比,肥液间歇入渗可以降低土壤的入渗能力,并且减渗效果主要体现在入渗的第二周期;肥液间歇入渗湿润锋运移较连续入渗速度慢,并随着周期数的增加而减小;提出了由连续入渗湿润锋运移资料计算间歇入渗湿润锋运移距离的模型;肥液间歇入渗土壤含水率较连续入渗的分布均匀;间歇入渗较连续入渗土壤NO₃^--N锋面运移速度慢,更有利于将NO₃^--N保持在浅层土壤中;在有地下水影响的条件下,连续入渗和间歇入渗在不同时间土壤NO₃^--N浓度与土壤含水率关系均近似于“倒L”型曲线,由高含水率段和过度段组成。与连续入渗相比,间歇入渗土壤NO₃^--N浓度与土壤含水率关系曲线更陡;连续入渗时,进入地下水中的硝态氮较多。（3）研究了波涌灌溉间歇入渗技术要素对肥液间歇入渗能力、湿润锋运移和土壤含水率分布、土壤NO₃^--N运移及其对地下水NO₃^--N分布的影响,分别建立了不同影响因素的肥液间歇入渗量和湿润锋运移模型。循环率为1/3时,间歇入渗减渗作用最大,有利于将NO₃^--N保持在浅层土壤中,进入地下水中的硝态氮最少,对地下水的污染最小;周期数为3时,间歇入渗减渗率最大,土壤硝态氮浓度锋迁移距离最小,间歇入渗进入地下水中的硝态氮最少;灌水定额越大,湿润锋运移深度越大,土壤硝态氮迁移的距离越大,随入渗水分进入地下水中的硝态氮越多。不同影响因素的肥液间歇入渗地下水中硝态氮浓度增加量与地下水深度之间呈幂数函数关系。（4）研究了不同浓度肥液间歇入渗情况下水肥耦合特性及地下水中NO₃^--N运移特性。入渗能力随肥液浓度的增大而增大;肥液浓度越大,间歇入渗NO₃^--N浓度锋运移距离越大,土壤剖面NO₃^--N浓度峰值越大;不同浓度肥液在间歇入渗结束时,土壤硝态氮浓度和土壤含水率的关系曲线近似一个横放的“V”字型,在地表以下0～72cm范围内,土壤硝态氮浓度和土壤含水率均比较大,且从上到下硝态氮浓度随含水率的减小而减小,肥液浓度越大,土壤含水率对土壤硝态氮浓度的影响越大,在72cm～150cm范围内,土壤硝态氮浓度接近初始状态,几乎不受土壤含水率的影响;随再分布时间的延长,不同浓度肥液间歇入渗土壤含水率和NO₃^--N浓度关系曲线更光滑,分布越均匀,在地表以下0～76cm范围内,土壤NO₃^--N浓度随土壤含水率的增加而减小,在地表以下76cm～150cm范围内,土壤硝态氮浓度较入渗结束时有所增加,肥液浓度越大,土壤含水率对土壤硝态氮浓度的影响越大;随水分入渗进入地下水的NO₃^--N主要集中分布在浅层地下水中,肥液浓度越大,进入地下水的NO₃^--N越多,对地下水的污染越严重,对于不同浓度肥液的间歇入渗,在入渗结束时进入地下水中的硝态氮最多,随再分布时间的延长,进入地下水中的硝态氮逐步减少。不同浓度肥液对应的地下水中NO₃^--N浓度增量与地下水深度呈指数函数降低关系。（5）研究了施肥方式对间歇入渗土壤水分、氮素运移特性及地下水NO₃^--N的影响。对于不同施肥方式的间歇入渗,表施肥的土壤入渗能力较灌施和深施的大;在相同入渗时间,湿润深度大小顺序为表施＞深施＞灌施＞不施肥;建立了不同施肥方式的土壤间歇入渗量模型;再分布1天后,相同湿润深度处,土壤含水率大小顺序分别为表施＞灌施＞深施;施肥方式对间歇入渗NO₃^--N运移和分布影响很大,相对而言,灌施间歇入渗土壤湿润范围内NO₃^--N分布相对较均匀,而表施与深施在某一深度土层内NO₃^--N分布较集中,而且随时间不断向深层土壤迁移;表施情况下土壤中的NO₃^--N随水分迁移的速度最快,相对表施与深施而言,灌施间歇入渗NO₃^--N更有利于保持在浅层土壤中,能够有效地降低水分和NO₃^--N深层渗漏损失;不同施肥方式的间歇入渗地下水硝态氮浓度随地下水深度的增加而增加,地下水硝态氮浓度随入渗时间的延长而增大;地下水硝态氮浓度的增加比率（不同入渗时间内地下水硝态氮浓度增量的绝对值占总入渗时间内地下水硝态氮浓度增加总量的百分比）随入渗时间的延长而减小,入渗结束时地下水硝态氮浓度的增加比率最大,再分布5天的增加比率最小;建立了不同施肥方式条件下地下水中硝态氮浓度的增量与地下水深度之间的指数函数模型;灌施的地下水硝态氮增量较表施和深施的小,灌施肥有利于提高氮肥利用效率,减轻氮肥对地下水的污染。更多还原

【Abstract】 On the basis of literature review on surge irrigation,nitrogen fertilizer transport and transformation in soils worldwides,considering irrigation and fertilization practice in China, this research involves laboratory studies and theoretical analyses.This dissertation covers researches on soil water and nitrogen transport characteristics,water and fertilizer coupling characteristics,the concentration of NO₃^--N in the ground water under surge infiltration with fertilization.Such research should provide the theoretical backgrounds for NO₃^--N pollution control of groundwater and improvement of nitrogen use efficiency.The main findings are as follows:（1）The capillary water ascending characteristics under in the uniform soil with different groundwater table are researched.The ascending rate of capillary water augments with the initial soil moisture;the height of the capillary water rise increases with time,the capillary water rise velocity decreases with time increasing;the more the initial soil moisture is,the less the time that capillary water reach to the same height is;the relationship between the height of the capillary and the time needed can be simulated by power functions.The little the initial soil moisture is,the more the underwater supply volume when soil water reach balance is and the longer the balance time is;there are power function relationship between the capillary water supply and time,and linear power function relationship between the capillary water rise velocity and the height of the capillary water rise.（2）The infiltration capacity,wetting front transport,soil water content distribution, NO₃^--N transport characteristics and the NO₃^--N concentration distribution of round water under intermittent and continuous infiltration with fertilizer solution are researched.Comparing with continuous infiltration,intermittent infiltration can decrease infiltration capacity and the reduction effects were more significant in the second cycle.Wetting front of the under intermittent infiltration with fertilizer solution moves slower than under continuous infiltration and the speed decreases with cycle number.Model for calculating transport distance of the wetting front under intermittent infiltration based on continuous infiltration data is proposed.The soil water content is more evenly distributed under intermittent infiltration than continuous infiltration.Soil NO₃^--N front under intermittent infiltration moves slowly than under continuous infiltration,which favors NO₃^--N conservation in shallow soil layer.The relationship curve between concentration NO₃^--N and soil water content is a "L" shape under intermittent and continuous infiltration effected by underwater.Comparing with continuous infiltration,the relationship curve is steeper under intermittent infiltration,and the NO₃^--N increment in the ground water is more under continuous infiltration.（3）The influences of technique factors on the infiltration capacity,wetting front transport, soil water content distribution,NO₃^--N transport characteristics and the NO₃^--N concentration under intermittent infiltration are researched.The infiltration quantity and wetting front transport models containing different affecting factors under intermittent infiltration with solution are established.In this experiment,the optimal cycle rate is 1/3,which leads to NO₃^--N being more easily stored in shallow soil layer and weakens the trend of NO₃^--N leaching and lightens groundwater NO₃^--N pollution;The infiltration rate,the concentration front transport distance of NO₃^--N and the increment of concentration of NO₃^--N in groundwater are least when the cycle number is 3.The wetting front and the concentration front transport distance and the NO₃^--N concentration increment in the groundwater increase with the irrigation water quota increasing.There is power function relationship between the increment of NO₃^--N concentration in the groundwater and the groundwater depth.（4）Coupled movement characteristics of soil water and nitrogen under intermittent infiltration with different fertilization concentration are researched.The infiltration capacity,the transport distance of NO₃^--N concentration front and the value of NO₃^--N front increases with the fertilizer solution concentration.After intermittent infiltration with fertilizer solution,the relationship curve between concentration NO₃^--N and soil water content is a "V" shape,in 0～72cm soil layer,NO₃^--N concentration and the soil water content are large.The NO₃^--N concentration decreases with soil water content decreasing.The more fertilization solution concentration is,the little the influence of soil water content on NO₃^--N concentration.The NO₃^--N concentration is close to initial value in 72cm～150cm,the "V" curve becomes more slipperier and the distribution of NO₃^--N concentration and soil water content are uniform. The NO₃^--N concentration decreases with soil water content increasing.In 0～76cm, NO₃^--N concentration increases more than after infiltration,the more solution concentration is,the more soil water content effect NO₃^--N concentration;NO₃^--N in underwater from irrigation water mainly distribute in the shallow groundwater,the more solution concentration is,the more NO₃^--N enters groundwater and the more seriously NO₃^--N pollutes,NO₃^--N entering groundwater is most after irrigation with different fertilization concentration and decreases gradually with redistribution time.The exponent function exists between the NO₃^--N increment of different concentration solution and groundwater depth.（5）The effect of fertilization applying manner on soil water content,nitrogen transport characteristic and NO₃^--N concentration in the groundwater are researched.The infiltration capacity of surface applying fertilization is more than chemigation and deep applying fertilization; in the same infiltration time,the order of wetting depth is surface applying fertilization＞deep applying fertilization＞chemigation＞no applying fertilization;the infiltration volume under intermittent infiltration with different fertilization applying manner is developed;in the same wetting depth,the order of soil water content is surface applying fertilization＞chemigation＞deep applying fertilization after redistribution for 1 day;the fertilization applying manner has great influence on NO₃^--N transport and distribution under intermittent infiltration.NO₃^--N in the wetting scope under chemigation infiltration distributes uniformly,while the NO₃^--N under surface applying fertilization and deep applying fertilization mainly distributes in the some depth and transports gradually to deeper soil with time;the NO₃^--N transports most fast with water under surface applying fertilization,comparing with surface applying fertilization and deep applying fertilization,intermittent infiltration with fertilizer solution favors the NO₃^--N conservation in shallow soil,and decreases effectively soil water and deep seepage of NO₃^--N; NO₃^--N concentration in the groundwater under intermittent infiltration with different fertilization applying manner increases with the underwater depth and infiltration time;the increase ration（the present of NO₃^--N concentration increase absolute value under different infiltration time to NO₃^--N increase gross under total infiltration time）of NO₃^--N concentration groundwater decreases with infiltration time,the increase ratio of NO₃^--N concentration is most after infiltration and least after redistribution for 5 days,the exponent function exists between the NO₃^--N concentration increment and groundwater depth under different fertilization applying manner,chemigation favors the improvement of the nitrogen use efficiency and mitigate the nitrogen pollution in groundwater.更多还原