盐渍化地区农田养分流失机理与调控机制研究

The study is conducted aimed at the situation of water shortage, low efficiency of water and nutrition and increasingly heavier environmental pollution caused by nitrogen and phosphorus enrichment at Inner Mongolia salinization irrigation district. The effect of coupling of water and fertilizer on crop physiology ecological and yield and quality will be quantitative studied, and water-salt-fertilizer-yield coupling model will be also made for looking for the fertigation methods of reducing nitrogen and phosphorus fertigation, improving the crop yield in the water and salt stress condition; We study the effect of different water and fertilization applications on the environments of soil and groundwater, research the influence of different the depth of groundwater on the movement of nitrogen and phosphorus, and show the annual variation law and cumulative effect of the movement of nitrogen and phosphorus in salinization irrigation district, develop the distributed non-point pollution model for salinization irrigation district based on AnnAGNPS model. The simulation will be applied to analyze the nitrogen and phosphorus loss for point, field, and regional scale under a variety of scenarios using the model, and finally label the key source area and priority control area of nitrogen and phosphorus loss in Hetao Irrigation District under the different fertigation mode and land use type, and establish the technology system of nutrient optimization application and partition application model of nutrient in salinization area to Realize high efficient utilization of water and fertilizer for different areas in Hetao Irrigation District, and reduce agricultural pollution to provide the theory basis.

本项目主要针对内蒙古盐渍化灌区水资源短缺、水肥利用率低及以氮磷为主的养分对环境污染日益加重的现状开展研究。通过定量研究水盐胁迫条件下水肥耦合对作物生理生态及产量品质的影响效应，构建水盐胁迫下水-盐-肥-产量耦合模型，寻求减氮控磷高产灌溉施肥模式；同时探索不同水肥施用条件下对土壤、地下水等环境影响效应与不同地下水埋深对氮磷迁移的影响效应，揭示盐渍化灌区氮磷迁移转化的周年规律及累积效应；基于AnnAGNPS模型构建盐渍化灌区分布式非点源污染模型，通过对不同情景下盐渍化条件下点尺度、农田尺度及区域尺度氮磷流失的模拟研究，标识出现有灌溉施肥模式及土地利用方式下河套灌区氮磷流失关键源区和优先治理区，从而建立盐渍化地区养分优化施用技术体系、分区施用模式及调控机制，为实现盐渍化灌区不同区域水肥高效利用，减少农业污染提供理论依据。

水资源短缺、土壤盐渍化及过量施肥制约了河套灌区农业可持续发展，而解决这一问题的有效措施是通过水肥调控达到水分、养分及盐分的平衡控制。课题通过不同尺度的试验模拟研究，揭示了盐渍化地区农田养分流失机理与调控机制。具体开展以下研究：1）开展了作物水肥耦合效应及减氮控磷水肥一体化研究，以河套灌区主要作物为研究对象，通过对不同水肥盐条件下作物生理生育指标及水肥利用效率等的测定分析，表明适度节水控肥不会降低作物的光合特性，合理氮磷配施能显著提高作物水肥利用效率，不会降低产量。盐分土壤中，施肥过多会导致土壤盐分增大，作物产量减小。通过综合分析，最终提出了盐渍化地区主要作物的最优水肥模式。2) 开展了不同水肥模式下水肥流失特征及对水土环境影响的研究。通过探究不同水肥施用条件对土壤EC、氮素迁移的影响，研究表明不同盐分土壤，随着灌水量的增加，土壤含水率增加，适当增加氮肥可以提高根系吸水量，从而降低土壤含水率。相同灌水条件下，同一土层施肥越多电导率越大；在轻、中度盐分土壤条件下，硝态氮随着施氮量增加而增加，施氮条件相同时，土壤硝态氮的含量随灌水量的增加呈先增加后减少的趋势；铵态氮的含量随着施氮量的增加而增加，灌水对铵态氮的影响不大。3)开展了基于SWAT模型的盐渍化灌区水肥迁移模拟研究，通过对SWAT模型边界条件的添加，并以解放闸灌域水量和氨氮负荷作为目标变量，选取了 Pearson系数（R2）和 Nash-Sutclife模拟系数（ENS）作为表征率定与验证结果的目标函数，对该模型在河套灌区的应用进行了适应性修正，进行了参数率定及模拟研究，结果表明R2 与ENS均达到模型精度要求。通过模拟获得灌域不同水文响应单元的氮磷空间分布特征。通过以上研究，初步提出了盐渍化灌区水肥最优施用技术体系。项目资助发表论文14篇（SCI/EI 3篇）。培养博硕士生6名。项目各项支出符合支出要求。