松嫩平原盐碱土改良影响下农田非点源氮素输出响应机制及分异特征研究

With the implementation of large-scale land consolidation and drinking water project, the way of planting rice on the saline-alkali soil aiming to improve it grows more and more popular in the Songnen Plain Agricultural District. However, in this context, the risk of nutrient loss, pollutant output, and water pollution, is further increased. Salinization and agricultural non-point source pollution output has become the two major problems to be resolved in the Songnen Plain. In this study, the saline-alkali paddy fields with different development years in Songnen Plain were selected as the area. By means of field observations in situ, plot experiment, isotope tracing, and indoor scene design experiment, this study aims to explore the distribution pattern of salt and nitrogen in farmland system under different fertilization systems; to reveal the different characteristics of salt and nitrogen output and transformation process in the background of agricultural development in seasonal and frost-free zone; to explain the relationship between the factors such as seasonal freezing and thawing process, development time, fertilization system and salt and nitrogen output. Based on the above research, the SWAP model was used to predict the trend of nitrogen pollution load in small scale. This research can provide theoretical and technical support for regional salinization improvement and the agricultural non-point source pollution control in the Songnen Plain, which will be the basis for the realization of regional ecological safety control.

随着大规模土地整理和饮水工程的实施，松嫩平原盐碱地改水稻田开展以水洗盐的面积呈逐年增加的趋势。在此背景下，以氮素为代表的农田养分的流失、污染物输出以及水环境污染等的风险进一步提升，盐碱化和农业非点源污染输出加大成为松嫩平原亟待解决的两大问题。本项目拟以松嫩平原不同开发年限的盐碱稻田为研究对象，借助野外原位监测、小区试验、同位素示踪、室内情景模拟等技术和手段，探明不同施肥制度下盐类与氮素在农田系统中的分配模式，揭示中高纬季节性冻融区农业开发背景下盐类、氮素输出与转化过程的分异特征，阐释季节性冻融过程、开发年限、施肥制度等制约因素与盐类、氮素输出的响应关系，在此基础上利用SWAP模型对小尺度下氮污染负荷变化趋势进行预测分析，以期为松嫩平原实现区域盐碱化改良与农业非点源污染控制的双赢进而实现区域生态安全调控提供依据。

本研究在松嫩平原盐碱地改良农业开发的背景下，针对如何降低改良过程中所产生的环境负面效应，拟以松嫩平原典型盐碱地改良稻田为研究对象，探究在种稻改良过程中土壤不同形态可溶性氮素在农田土壤系统中的含量变化特征及其影响机理，阐明中高纬度地区典型的季节性冻融交替过程对盐碱地改良稻田土壤可溶性氮素影响的作用机理，并揭示其中微生物群落的响应特征，为明确人为改良和气候变化对松嫩平原盐碱化土壤氮循环提供理论依据，也为提出松嫩平原盐碱地改良与农业氮素污染防治的协同调控提供理论和技术支撑。