济南引黄灌区农田氮素淋失特征研究

发布时间：2018-06-23 09:14

  本文选题：济阳葛店灌区 + 氮素　； 参考：《济南大学》2016年硕士论文

【摘要】：氮素是作物生长及发育的重要营养元素之一,自然条件下,氮素一般处于动态平衡,而农田生态系统,人们为追求作物产量的最大化,长期向土壤中不合理过量的投入氮肥,导致水土环境中氮素含量积累,加之农田生态系统不同于自然生态系统,其人为干扰程度较大,且没有足够的自净能力,不合理的人类活动会对其产生较大影响,进而影响农田氮素迁移淋失特征,据前期调查济南葛店引黄灌区水土环境中氮素面源污染严重,本文旨在研究水稻-小麦生长期内土壤剖面、浅层地下水环境中氮素累积分布、淋失特征及影响因素分析,基于Hydus-3D软件模拟不同设计施肥灌溉方案下包气带氮素迁移转化特征,确定适合灌区较优的水肥方案。主要研究内容及结论如下:(1)水稻-小麦作物生长年内系统采集0~120cm土壤剖面土壤样品,分析不同作物生长期土壤剖面氮素累积分布特征。研究表明,水稻-小麦生长年内,硝态氮与铵态氮含量变化趋势基本一致且随施肥灌溉处理其含量变化趋势响应明显;此外,水稻生长期内,土壤剖面氮素在80~100cm土壤累积现象明显,硝态氮净累积量为97.46kg/hm2,铵态氮净累积量为3.65 kg/hm2。(2)利用灌区土壤样品原状填充有机玻璃土柱进行室内实验,收集0~120cm土壤剖面渗滤液测定氮素含量,研究作物不同时期0~120cm土层剖面氮素淋失特征,结果表明,随作物生长发育,土壤剖面氮素淋失量减少,作物生长初期淋失量最多,成熟期量淋失量最少;相比总氮、铵态氮,硝态氮浓度曲线斜率大且稳定最小浓度时间短,与硝态氮最易淋失特点相符,土壤铵态氮含量少且矿化生成铵态氮明显,致使铵态氮淋失量波动较小。(3)采集土壤样品的同时采集浅层地下水,观测浅层地下水埋深变化,分析浅层地下水中氮素含量及其影响因素,浅层地下水中氮素含量随作物生长发育明显升高,水稻部分生长期硝态氮含量大于30mg/L,低于浅层地下水质量Ⅴ类标准,水稻-小麦生长年内浅层地下水中铵态氮含量均大于0.5mg/L,最大值为1.83mg/L,作物收割休闲期含量为0.75mg/L,低于浅层地下水质量Ⅳ类标准,说明灌区不合理的施肥灌溉已经污染浅层地下水水环境。(4)对影响土层氮素累积因素土壤有机质、土壤质地、灌水量分析,得出有机质与土壤剖面氮素具有较好的正线性相关,有机质是土壤氮素赋存的重要载体,不同土壤质地氮素累积量存在较大差异,累积量大小顺序:粘壤土壤土砂质壤土,灌溉对水土环境中氮素的分布、淋失特征影响较大,过量灌溉易造成氮素淋。(5)为缓解灌区氮素对土壤、浅层地下水质量的影响,设计不同水肥方案,基于Hydus-3D软件模拟包气带氮素迁移转化,优化提出较适合灌区的水肥方案。
[Abstract]:Nitrogen is one of the important nutrient elements in crop growth and development. Under natural conditions, nitrogen is generally in dynamic balance. In order to maximize crop yield, the farmland ecosystem, people in order to achieve the maximum crop yield, long-term unreasonable excessive input of nitrogen fertilizer in the soil. As a result of nitrogen accumulation in soil and water environment and the difference between farmland ecosystem and natural ecosystem, the degree of human disturbance is greater, and there is not enough self-purification ability. Unreasonable human activities will have a great impact on it. According to the investigation of nitrogen non-point source pollution in the soil and water environment of Gedian Yellow River Irrigation area in Jinan, the purpose of this paper is to study the soil profile in rice and wheat growing period and the accumulation and distribution of nitrogen in shallow groundwater environment. Based on Hydus-3D software, the characteristics of nitrogen transfer and transformation in aeration zone were simulated under different fertilization and irrigation schemes, and the suitable water and fertilizer schemes were determined. The main contents and conclusions are as follows: (1) soil samples of 0~120cm soil profile were collected systematically during the growing years of rice and wheat crops, and the characteristics of soil nitrogen accumulation and distribution in different crop growing periods were analyzed. The results showed that the change trend of nitrate nitrogen and ammonium nitrogen content was basically the same during the growing years of rice and wheat, and the change trend of nitrate and ammonium nitrogen content was obvious with fertilization and irrigation, in addition, during the rice growing period, the change trend of nitrate nitrogen and ammonium nitrogen content in rice growing period was obvious. The accumulation of nitrogen in soil profile was obvious in 80~100cm. The net accumulation of nitrate and ammonium were 97.46 kg / hm ~ 2 and 3.65 kg 路hm ~ (2) 路hm ~ (2) respectively. (2) the soil samples were filled with organic glass soil column in irrigation area. 0~120cm soil profile leachate was collected to determine nitrogen content, and the characteristics of nitrogen leaching in 0~120cm soil profile at different crop stages were studied. The results showed that the nitrogen leaching loss in soil profile decreased with crop growth and increased in early crop growth. Compared with total nitrogen and ammonium nitrogen, the curve slope of nitrate concentration curve was larger and the time of stable minimum concentration was shorter than that of total nitrogen, which was consistent with the characteristics of most easy leaching of nitrate nitrogen, and the soil ammonium nitrogen content was less and mineralized to produce ammonium nitrogen obviously. As a result, the amount of ammonium nitrogen leaching fluctuates less. (3) collecting soil samples and collecting shallow groundwater, observing the change of shallow groundwater depth, analyzing nitrogen content in shallow groundwater and its influencing factors. Nitrogen content in shallow groundwater increased obviously with crop growth and development. Nitrate nitrogen content in some growing stages of rice was more than 30 mg / L, which was lower than the class V standard of shallow groundwater quality. During the growing years of rice and wheat, the content of ammonium nitrogen in shallow groundwater was greater than 0.5 mg / L, the maximum value was 1.83 mg / L, and the content in crop harvest and leisure period was 0.75 mg / L, which was lower than the grade 鈪，

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