【作者】 刘小刚；

【导师】 张富仓；

【作者基本信息】 西北农林科技大学 ， 农业水土工程， 2009， 博士

【摘要】 水肥利用率低是我国农业生产发展中面临的重大问题。如何提高作物水分和养分的利用效率,调节作物生长的农田水肥环境是当前我国北方旱区发展节水农业迫切需要解决的关键问题。近年来,从有限水量在作物生育期内最优分配方面考虑提出的“控制性根系分区交替灌溉”和“调亏灌溉”等先进灌水技术的广泛研究和应用,确实对改善作物生长的土壤水分状况,提高灌溉水分利用效率起到了重要的作用;同时灌溉条件下的水肥高效利用研究也是近年来较多学者广泛关注的一个重要问题。因此对控制性根系分区交替灌溉和调亏灌溉条件下作物根区水氮迁移和高效利用机制的研究,对于合理利用农田水肥资源,节水节肥具有重要的理论与现实意义。论文通过盆栽和田间试验,系统研究和分析了小麦、玉米在节水灌溉条件下根区水氮迁移和高效利用机制,研究取得了以下主要结论:（1）控制性根系分区交替灌溉条件下玉米根区水氮迁移和利用的研究表明,施氮后盆内土壤硝态氮含量和施氮量呈正相关,交替灌溉根区两侧的土壤硝态氮分布均匀,固定灌溉干燥侧的土壤硝态氮累积量明显大于湿润侧。交替灌溉上层土壤硝态氮的残留量和常规灌溉同一层次上的残留量相当,下层硝态氮的残留量比常规灌溉的大。交替灌溉的水分利用效率是常规灌溉的1.16～1.03倍,而灌水量是常规灌溉的0.75倍,节水效果明显。（2）交替隔沟灌溉条件下玉米根区土壤水氮迁移和累积动态研究表明,收获时低水高氮处理在整个剖面上硝态氮的累积量最大是高水高氮处理的1.2倍,低水低氮处理是高水低氮处理的1.27倍。施氮后表层0～30 cm土壤铵态氮含量和累积量达到高峰,30 cm以下变化不明显。氮素水平高低对土壤水分的累积影响不大。高水处理减小了根区硝态氮的累积而产生淋失,降低了氮肥的利用效率。最佳的水氮耦合形式为交替隔沟灌溉低水高氮。（3）隔沟灌溉条件下不同根区施氮对土壤水氮迁移和利用机制的研究表明,水氮同区高水处理更容易导致硝态氮的淋失,收获时水氮同区高氮高水和水氮同区低氮高水的施氮沟剖面上硝态氮浓度基本相同。水氮异区高氮低水的籽粒产量最大为9953 kg·hm^-2,并且籽粒灌溉水分利用效率也最高为6.70 kg·m^-3,比水氮同区高氮高水的水分利用效率提高72.68%。最佳的水氮耦合形式为异区隔沟灌溉高氮低水。（4）对遮雨棚下不同沟灌模式和氮肥处理的玉米根区水氮迁移和利用的研究表明,交替隔沟灌溉中水低氮处理的产量最高,是交替隔沟灌溉高水高氮产量的1.06倍。在相同水分和氮肥条件下,交替隔沟灌溉的平均产量可达9317 kg·hm^-2,分别是常规沟灌和固定隔沟灌溉的1.05和1.16倍。交替隔沟灌溉的水分利用效率最大均值为3.39 kg·m^-3,常规沟灌的次之,固定隔沟灌溉的最小为2.94 kg·m^-3。交替隔沟灌溉的全氮累积总量最大,常规沟灌的次之,其中固定隔沟灌溉的小于交替隔沟灌溉的均值可达26 kg·hm^-2。灌水量和施氮量相同时,交替隔沟灌溉的根区硝态氮等值线和常规沟灌的相似,沟内硝态氮含量基本沿垄的中心对称分布。（5）调亏灌溉与氮营养对盆栽玉米根区水氮有效性的研究表明,调亏灌溉根区中下层土壤硝态氮含量介于非调亏灌溉的高水、低水处理之间。抽穗期结束时中下层土壤硝态氮含量与施氮量呈正相关关系。施氮量、调亏时期对干物质和全氮累积量的影响显著。拔节期水分亏缺对干物质累积量影响最大。高氮苗期调亏的水分利用效率最高。最佳的水氮组合为抽穗期亏水低氮处理。（6）调亏灌溉和氮素处理的盆栽玉米生理生化特性的研究表明,水分亏缺导致了叶绿素含量降低,施氮量和叶绿素含量正相关。水分亏缺会使玉米叶片脯氨酸含量增加,施氮会使脯氨酸含量略有减少。在水分亏缺条件下,根系活力降低,覆水后根系活力补偿效应明显。调亏灌溉可使玉米叶片的丙二醛和可溶性糖含量明显升高,而过氧化物歧化酶和超氧化物歧化酶含量有所降低。施氮处理能保证叶片在抽穗期前的可溶性糖、过氧化物歧化酶和超氧化物歧化酶的含量处于较高的水平。苗期亏水处理在覆水后各生理生化指标补偿效果较好,拔节期亏水处理的次之。高氮处理不宜在抽穗期调亏灌溉。最佳处理组合为苗期调亏低氮处理。（7）调亏灌溉和氮肥处理对石羊河流域春小麦群体水氮利用的影响结果表明,施氮量、拔节期和抽穗期灌水对干旱区春小麦的产量影响显著;施氮量168 kg·hm^-2、拔节期灌水90 mm、抽穗期灌水70 mm可获得较高籽粒产量。施氮量对地上干物质和籽粒的氮素累积量影响显著;拔节期灌水为90 mm,施氮量为168 kg·hm^-2时籽粒的氮素累积量最大。石羊河流域春小麦的最优灌水施氮模式为:施氮量为168 kg·hm^-2,全生育期灌水4次,拔节期灌水为90 mm,分蘖期、抽穗期、灌浆期灌水均为60 mm。（8）调亏灌溉对石羊河流域春小麦根区水氮迁移和利用的研究表明,在春小麦拔节前各处理的根区土壤硝态氮累积主要集中在剖面0～40 cm处,其累积量都约为550 kg·hm^-2。播后62天起高水处理的根区土壤硝态氮出现淋失,其硝态氮累积量是特低水处理在整个剖面上累积量的0.76倍。收获时根区土壤硝态氮的残留量特低水处理>低水处理>中水处理>高水处理。当水资源严重匮乏时,春小麦全生育期补灌360～280 mm可以保证有较高的产量和较高的水分利用效率。更多还原

【Abstract】 Low efficiency of water and fertilizer is a main problem faced by agricultural production. How to improve the efficiency of water and fertilizer and adjust environment of water and fertilizer are urgent need to solve the key issues in developing water saving agriculture in dry areas of North China. Advanced water-saving technology were widely studied and applied considering optimal allocation of limited water in crop growth stages, such as controlled roots-divided alternative irrigation and regulated deficit irrigation could improve indeed irrigation water use efficiency and crop growth soil water situation. Many scholars have paied more and more attention to the efficiency of water and nutrient. So the research on transport of water and nitrogen efficient utilization mechanism in crop rootzone soil under water-saving irrigation has theory and realistic meaning in fair use water and fertilizer resources and water-saving and fertilizer-saving. The transport and utilization of water and nitrogen in rootzone soil was studied and systematic analyzed by pot and field experiments about maize and wheat under water-saving irrigation condition. After studying I have preliminarily obtained some major research results as follows:（1） The transport and utilization of water and nitrogen in rootzone soil was studied of controlled roots-divided alternative irrigation. Results showed that, Soil NO₃^--N content were positively correlated with amount of nitrogen application, Soil NO₃^--N content in both rootzone of alternative irrigation was evenly distributed, and the soil NO₃^--N accumulation in dry side was significantly greater than wet side of fixed irrigation. The NO₃^--N residues in upper soil of alternative irrigation was approximately equal with them of convention irrigation, while the residues in lower soil of alternative irrigation were much than them of convention irrigation. The WUE of alternative irrigation were 1.16～1.03 times it of convention irrigation, the irrigation amount of alternative irrigation is 0.75 times it of conventional irrigation, water-saving effects of alternative irrigation was evident.（2） Effects of alternative furrow irrigation on transport and accumulation of water and nitrogen in maize rootzone soil were investigated. The results showed that, The maximal accumulated NO₃^--N of low water and high nitrogen was gained in the whole profile at harvest time, which was 1.2 times of that of high water and high nitrogen. The accumulation of NO₃^--N of low water and low nitrogen was 1.27 times of that of low nitrogen and high water. NH4+-N contents in the soil of 0～30 cm reached a peak, and the contents basically did not change below 30 cm soil after fertilizing. Soil water accumulation and distribution was not obviously affected by the level of nitrogen. The treatment of high water reduced the accumulation of NO₃^--N in root zone, which lead to leaching and reduced nitrogen fertilizer use efficiency. The best coupling form of alternative furrow irrigation was treatment of low water and high nitrogen.（3） Transport and utilization mechanism of water and nitrogen in spring maize rootzone soil were studied about separate furrow irrigation and nitrogen application in deffrent rootzone （fertilizing in the irrigated furrow （FII） and unirrigated furrow （FIU））. Results showed that high water of FII was more easily lead NO₃^--N leaching, the content of NO₃^--N was basically equal in the profile of treatment of high water of FII at harvest time. The treatment of high nitrogen and low water of FIU had maximum grain yield of 9953 kg·hm^-2 and highest grain irrigation water use efficiency （IWUE） of 6.70 kg·m^-3, compared with IWUE of treatment of high nitrogen and high water of FII, it raised by 72.68%.The best form of water and nitrogen space coupling was treatment of high nitrogen and low water of FIU.（4） Transport and utilization of water and nitrogen in spring maize rootzone soil was studied about different furrow mode and nitrogen rate under rain canopy. The results showed that, the treatment of CAFI, middle water and low nitrogen rate reached the highest yield, which was 1.06 times it of CAFI, high water and high nitrogen. Maize average yield of CAFI could reach 9317 kg·hm^-2, it was respectively 1.05 times of CFI and 1.16 times of FFI under the same condition of water and nitrogen. The average WUE of CAFI was 3.39 kg·m^-3,it of CFI took the second place; it of FFI reached the minimum value of 2.94 kg·m^-3. Nitrogen cumulant of CAFI was the maximum,nitrogen cumulant of CFI took the second place, and it of FFI was less 26 kg·hm^-2 than CAFI. NO₃^--N contour of CAFI in rootzone soil was similar to that of CFI under the same condition of irrigation quality and nitrogen rate, and NO₃^--N content in furrow profile was along the symmetry of ridge center.（5） The effect of regulated deficit irrigation and nitrogen nutrition on availability of water and nitrogen in maize rootzone was studied. The results showed that, NO₃^--N content in middle and lower soil layer of regulated deficit irrigation lies between the treatment of low and high water of normal irrigation, there was a positive correlation between the content of NO₃^--N in middle and lower soil layer and N rate at end of the heading stage. N rate and deficit period had a notably significant effect on accumulation of dry matter and total nitrogen. Water deficit at jointing stage affected mostly dry matter accumulation. The treatment of high nitrogen and deficit water at seedling stage had the maximum WUE. The best coupling treatment was deficit water in heading stage and low nitrogen.（6） The effect of regulated deficit irrigation and nitrogen nutrition on physiological characteristics of maize was studied. The results showed that, water deficit led to lower chlorophyll content; nitrogen rate and chlorophyll content was positively relevant. Water deficit would increase the proline content; the nitrogen apply would slightly reduce the proline content. Water deficit reduced root activity; compensation effect of root activity was obvious after water covered. Deficit irrigation could increase MDA and soluble sugar content, while decrease POD and SOD content. Nitrogen could ensure soluble sugar, SOD and POD at a higher level before heading date. The treatment of deficit irrigation in seedling stage had better compensation effect of biochemistry; deficit irrigation in jointing stage had less compensation effect. The treatments of high nitrogen were not suitable to be irrigated deficit in the heading stage. The best handling combination was deficit irrigation in seedling stage with low nitrogen.（7） Spring wheat population utilization of water and nitrogen in Shiyang River was studied about regulated deficit irrigation and nitrogen rate. The results showed that nitrogen rate and irrigation in jointing and heading stage impacted on spring wheat yield remarkably. With nitrogen rate (168 kg·hm^-2), irrigation （90 mm） in jointing stage, and irrigation （70 mm） in heading stage, spring wheat production is higher. The impact of nitrogen rate on nitrogen accumulation of grain yield and dry matter were significant; nitrogen accumulation of grain came to maximum when nitrogen rate (168 kg·hm^-2) and irrigation （90 mm） were applied. The optimal model of irrigation and nitrogen rate of spring wheat in Shiyang River Basin were nitrogen rate(168 kg·hm^-2), irrigation（90 mm） in jointing stage and irrigation（60 mm） in tillering、heading、filling and jointing stage.（8） Utilization mechanism and transfer of water and nitrogen was studied about regulated deficit irrigation in Shiyang River. The results showed that NO₃^--N accumulation in root soil was mainly concentrated in the 0～40 cm profile before the jointing stage and the accumulation was about 550 kg·hm^-2. NO₃^--N was leaching in the rootzone soil of high water treatment from 62 days after sowing, the NO₃^--N accumulation of high water treatment was 0.76 times of that of lower treatment in the profile. The residual of NO₃^--N was in sequence of lower water>low water>middle water>high water at harvest time. Supplementary irrigation amount of 360～280 mm in the whole growth period could guarantee yield and water use efficiency on the condition of deficit water resources.更多还原