基于土壤—作物系统叶绿素氮诊断的优化水氮模式研究

发布时间：2018-08-10 20:15

【摘要】：内蒙古河套灌区存在引黄水量骤减,氮肥施用量大,农业面源污染较严重的问题。在该灌区开展优化水氮模式的研究是提高农业清洁生产水平和推进现代化农业的重要科技需求,也是维护灌区农业环境的重要举措。本研究通过田间试验,揭示土壤-作物系统对水氮互作的反馈机理,并从叶绿素CCI值的角度对玉米进行氮营养诊断,提出适宜水氮配施比,为节约灌溉水资源,科学控制氮肥用量,改善农田环境提供有益的参考指标。主要结论如下:(1)玉米生理形态指标(株高、茎粗、叶面积、叶片叶绿素含量及根系形态)及土壤环境因子(土壤水盐、土壤有机质、硝态氮铵态氮、土壤氮素矿化速率)均随灌水量的升高而增加,灌水量90mm和120mm之间差异性不显著。施氮量在135～225 kg/hm2之间的玉米生理形态指标和土壤环境因子的增加效果显著,在施氮量为225 kg/hm2时出现峰值。当施氮量为280 kg/hm2时,上述各指标呈下降趋势。(2)灌水量90mm分别比60mm和120mm的玉米产量增加了17.93%和 3.28%。施氮量 225 kg/hm2 比施氮量 135 kg/hm2 和 180 kg/hm2分别增产11.77%和8.02%,施氮量280 kg/hm2比225 kg/hm2的产量降低了 2.58%。水分利用效率随施氮量的增加而增加,随灌水量的增加而降低。氮肥利用率与灌水量和施氮量之间均呈正相关关系。当灌水量为90mm,施氮量为225 kg/hm2时,玉米产量和氮肥利用率出现峰值。(3)本试验建立了河套灌区单种玉米临界氮浓度稀释曲线模型(Nc=35.94W-0.34),此模型可以用来诊断玉米氮营养状况,诊断结果为:当灌水量为90mm时,225 kg/hm2附近为较优施氮量区间,氮营养指数与叶绿素CCI值呈显著水平,玉米相对产量与叶绿素CCI值呈极显著水平。在临界氮浓度稀释曲线模型诊断的基础上,由线性加平台模型进一步确定玉米适宜施氮量为21 7kg/hm2。因此,本研究提出玉米的优化水氮模式为灌水量90mm,施氮量217 kg/hm2。
[Abstract]:In Hetao Irrigation area of Inner Mongolia, the amount of water diversion from the Yellow River decreased sharply, the application of nitrogen fertilizer was large, and the agricultural non-point source pollution was serious. The research of optimizing water and nitrogen model in this irrigation area is an important scientific and technological demand for improving the level of clean agricultural production and promoting modern agriculture, and is also an important measure to maintain the agricultural environment of irrigation district. In this study, the feedback mechanism of soil-crop system on the interaction between water and nitrogen was revealed through field experiments, and the nitrogen nutrition of maize was diagnosed from the point of view of chlorophyll CCI value, and the suitable ratio of water and nitrogen application was put forward to save irrigation water resources. Scientific control of nitrogen fertilizer use, improve the farmland environment to provide a useful reference index. The main conclusions are as follows: (1) physiological and morphological indexes (plant height, stem diameter, leaf area, leaf chlorophyll content and root morphology) and soil environmental factors (soil water and salt, soil organic matter, ammonium nitrate nitrogen) in maize; Soil nitrogen mineralization rate) increased with the increase of irrigation amount, but there was no significant difference between irrigation amount 90mm and 120mm. The physiological and morphological indexes of maize and soil environmental factors increased significantly in the range of 135 ~ 225 kg/hm2, and the peak value appeared when the N application rate was 225 kg/hm2. When the amount of nitrogen applied was 280 kg/hm2, the above indexes showed a downward trend. (2) the yield of 90mm increased 17.93% and 3.28% than that of 60mm and 120mm, respectively. The yield increased by 11.77% and 8.02% at 225 kg/hm2 than that at 135 kg/hm2 and 180 kg/hm2, respectively, and the yield at 280 kg/hm2 decreased by 2.58% compared with that at 225 kg/hm2. Water use efficiency (Wue) increased with the increase of nitrogen application rate and decreased with the increase of irrigation amount. There was a positive correlation between nitrogen fertilizer use efficiency and irrigation amount and nitrogen application rate. When the irrigation amount was 90 mm and the nitrogen application rate was 225 kg/hm2, the maize yield and nitrogen fertilizer utilization rate reached the peak. (3) the model of critical nitrogen concentration dilution curve (Nc=35.94W-0.34) of single maize in Hetao irrigation area was established, which could be used to diagnose the nitrogen nutrition status of maize. The diagnostic results were as follows: when the irrigation amount was 90mm, the optimum nitrogen application range was around 225 kg/hm2, the nitrogen nutrition index and chlorophyll CCI were significant, and the relative yield of maize and chlorophyll CCI were extremely significant. Based on the diagnosis of the model of critical nitrogen concentration dilution curve, the optimum nitrogen application rate of maize was determined to be 21.7 kg 路hm ~ (2) by the linear plus platform model. Therefore, the optimal water and nitrogen model of maize is 90 mm irrigation and 217 kg / hm ~ 2 N application.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：S513

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