【作者】 习金根；

【导师】 周建斌；

【作者基本信息】 西北农林科技大学 ， 植物营养学， 2003， 硕士

【摘要】 水分不足和养分缺乏是制约广大旱农地区生产的两个关键因素。如何有效地对二者进行调控，达到高产、优质和高效的生产目的，国内外已进行了大量的研究。灌溉施肥是生产中经常采用的一种水肥调控技术，但施肥不匀，养分流失，容易引起作物灼烧等，是传统的灌溉施肥方法常常遇到的问题。滴灌施肥作为一种先进的水分调控技术，近年来国外已开始广泛采用，但对滴灌施肥条件下肥料养分在土壤中迁移转化规律的了解尚十分有限。本研究采用室内模拟试验和生物培养试验相结合的方法，研究了在滴灌施肥条件下，化学氮肥施入土壤后的迁移、转化规律以及对作物生长的效应，获得了以下主要结论： （1）滴灌条件下水分以点源入渗土壤，水平和垂向的湿润锋均随入渗时间的增加而逐渐变大，在入渗开始阶段湿润锋的推进速率较大，随入渗时间的延长，湿润锋的推进速率逐渐变慢。粘质（土娄）土，由于质地细小，在滴灌速率为2.67L／h时，湿润锋径向移动速率远大于垂向移动速率，前者是后者的1.22倍。比较了不同模型拟合的滴灌条件下土壤湿润锋的动态变化，认为多项式模型的拟合程度较好；同时建立了土壤湿润体水分含量（Y）与径向距离（L）、垂向距离（H）、实验时间（T）之间的经验关系式。这些模型为设计滴灌系统，包括滴头间距、灌水历时和灌水量等提供了理论参考；同时对于确定滴灌条件下养分在土壤中的运移特性，也十分重要。 （2）灌水量及水肥供应方式是决定尿素态氮在土壤中迁移、转化和淋失的关键因素。氮素淋溶量随灌水量的增加而增加；在淋失的N素形态中，以尿素态氮为主，其次为硝态氮，铵态氮的淋失量最低。与浇灌施肥相比，滴灌施肥显著地降低了氮素的淋溶损失。灌水量低时，滴灌施肥铵态氮在土壤上层明显累积；灌水量增加后，这种累积作用减弱。土壤硝态氮的变化趋势为，灌溉施肥灌水量低时，上低下高；增加灌水量降低了土壤中硝态氮含量。总之，与浇灌施肥相比，滴灌施肥显著地减少了尿素态氮的淋溶损失，增加了土壤中有效态氮的含量。 （3）在滴灌施肥条件下，三种氮肥（硝态氮、铵态氮和尿素态氮）在两种质地的土壤中的淋失量均是硝态氮肥＞尿素＞铵态氮肥，淋失的氮素主要为肥料氮。沙质土壤中氮素的淋失量明显高于粘质土壤。滴灌施用铵态氮肥显著增加了土壤中NH₄⁺-N含量，随着硝化作用的进行，NH₄⁺-N含量降低，NO₃^--N含量增加。施用尿素后，其转化为NH₄^--N数量在培养的第5d左右达高峰，尔后由于转化为NO₃^--N等过程的进行，含量逐渐降低。与滴灌施用硝态氮肥相比，施用铵态氮肥和尿素后在培养期间土壤矿质态氮（N03一N+NH犷一N）的含量有降低的趋势，降低的原因可能与NH4+一N在土壤中的固定、挥发及硝化等过程有关。 （4）滴灌施肥不同程度地提高了玉米根系活力、叶绿素含量、叶片硝酸还原酶活性和作物叶片的瞬时水分利用效率，明显地增强了作物的光合作用，显著增加了玉米对氮素养分的吸收和干物质的累积，其中地上部总干重和籽粒干重增加幅度分别为49.55%和67.57%。滴灌施肥与浇灌施肥相比，水分利用效率增加幅度为109.20%。肥料氮素利用率达73.55%，增加幅度为1 10.44%。可见，滴灌施肥可以明显地提高水分和肥料氮素的利用率。这与滴灌施肥可以合理地调控土壤水分和养分供应，为作物生长提供一个理想的生长环境有关。 研究认为，滴灌施肥技术在我国特别是在土壤贫瘩、缺水严重的地区有着巨大的应用前景。进一步开展滴灌施肥条件下氮素转化运移的模型研究和发展动态监测水氮转化和运移技术等，是值得研究的问题。更多还原

【Abstract】 Water and nutrient deficiencies are two key factors of limiting the development of agriculture in the dry land. Many of the researches carried out have concentrated on how to apply water and nutrients effectively to achieve the goal of high yield, good quality and high efficiency. Adding fertilizers through the irrigation water (i.e. fertigation) is one of common ways of fertilization. However, the uneven distribution and leachings of nutrients and induced crop damage are the common problems for the traditional way of fertigation. Fertigation by drip irrigation as an advanced technology to control the supply of water and nutrients has been applied by other countries in recent years. However, the movement and transformation of N in soil under fertigation remains unclear. The methods of simulation experiment and culture experiment were used to study the movement and transformation of N in soil under fertigation by drip irrigation. The main experimental results were shown as folio wings:(1) The water infiltration under drop irrigation is a point infiltration; and the soil moisture in vertical and horizontal directions was increased with the irrigation time, and the movement rate were decreased with the irrigation time. And compared to the vertical wetting front, the rate of horizontal wetting front was 1.22 times higher. Different models were used to fit the movement of wetting front, it is found that the polynomial function was a good model. We also use polynomial function to model the soil moisture under drip irrigation; and the function will be useful for design the drip irrigation system and fertigation system.(2) The amount water added and the way of supplying water and fertilizer were two key important factors to affect the movement, transformation, and leach of urea-N in soil. The amount of nitrogen leached was increased with the increasing amount of water applied. And compared to the treatment of fertilizer added as flooding irrigation (FIF), the treatment of fertilizer added in drip irrigation (DIF) significantly decreased the nitrogen leached. The main form of N leached was urea-N, next was NCV-N; the proportion ofNH4+ N leached was very low. The NH4+-N accumulated in the upper layer of soil when the irrigation water was low; and at the high irrigation rate, this accumulation was decreased. With the low irrigation water, the content of NO3--N was lower in the upper layer of soil, and higher in deeper soil layers. As the increase of water added, the level of NO3-N in soils was decreased, In comparison with FIF, it is concluded that DIF significantly decreased the leaching loss of urea-N from soil, and increased the available nitrogen in soil.(3) The amount of nitrogen leached was in the decreasing order as NO3-fertilizer> urea>NH4+-fertinzer, and the main form of N leached was the N fertilizers added. The amount of nitrogen leached from sand soil exceed in that from clay soil. Applying NH4+-fertilizer can significantly increase the content of NH4+-N in soils, and as the processing of nitrification the content of NH4+-N was reduced, and NO3--N was increased gradually. After applying the urea, the content of NH4+-N in soils reached up to the peak in the fifth day or so, then began to decrease because of the occurring of the nitrification. The content of mineral nitrogen content (NH4+-N + NO3-N) decreased during the incubation period after applying NH4+-N fertilizer and urea. It maybe relates to the NH4+-N fixation, volatilization, and its nitrification.(4) Fertigation by drip irrigation increased the N uptake and accumulation of dry matter of summer maize, and improved the activity of crop photosynthesis. Root activity, NRA, and Pn/E were also increased by fertigation. When fertilizer was added as fertigation, the recovery of nitrogen fertilizer was high as 73.55%, with the 110.44% of increasing rate compared to traditional fertilization way; and corresponding increasing rate in dry weight of shoot and grain yield and water use efficiency were 49.55%, 67.57%, 109.20%, respectively. Obvi更多还原