为提高氮肥利用效率，减少资源浪费，改善生态环境问题，需要对农田氨挥发进行实时在线监测。将可调谐半导体激光吸收光谱 (TDLAS) 技术和开放式长光程技术、波长调制技术、光纤传感技术和时分复用技术相结合，设计了开放式多路氨气监测系统，在中国科学院封丘农业生态实验站进行了农田施肥后氨气质量浓度的实时在线监测。结果表明氨气质量浓度具有一定的日变化趋势，基本特点是白天高，夜晚低，主要在施肥后一周达到最大值，之后逐渐降低。该系统监测范围广、灵敏度高、响应时间快和不需气体采样，为农田环境的氨挥发连续监测提供了有效方法。

In-situ monitoring ammonia volatilization is needed to improve nitrogen fertilizer utilization efficiency, reduce the waste of resources, and solve eco-environmental problems. Open multi-path NH3 monitoring system has been developed based on tunable diode laser absorption spectroscopy (TDLAS) technology combining with long open-path technique, wavelength modulation technique, fiber sensing technique and time division multiplexing technique, which are used for ammonia concentration in-situ detection after farmland fertilization at Fengqiu experimental station of agro-ecology, Chinese academy of sciences. Monitoring results show that the variation of ammonia concentration has an obvious diurnal periodicity, the general characteristic of diurnal variation shows that the concentration is high in the daytime and is low at night. Ammonia concentration reaches the maximum after a week for fertilization, and then decreases gradually. This system detects gas concentration with large range, high sensitivity, short response time without gas sampling. Thus, it is an effective method for ammonia volatilization monitoring in farmland environment.