Soil respiration is the main process of carbon and nitrogen circulation between the earth and atmosphere. Real-time in-situ measurement of gas emissions from different ecological soil environments is a powerful tool for studying the dynamic processes of atmospheric-greenhouse-gas formation, transfer, and consumption, which provides the key scientific basis for revealing the main processes of carbon and nitrogen ecosystem cycling and environmental evolution. In this paper, we describe the development of a laser-spectroscopy system based on a room-temperature, continuous-wave, quantum-cascade laser (RT-CW-QCL), a long-path optical-absorption cell, and a direct-absorption spectroscopic detection technology for the high-sensitivity and high-precision analysis of CO and N₂O gas-exchange processes between soil samples under different ecological environments and ambient air. The results show that soil samples from four different ecological environments (i.e., reed, pond, organic, and grassland soils) exhibit visibly different CO and N₂O release and absorption processes.