Against the backdrop of urban expansion and increasingly tense land use, many landfills are forced to be set up on the edge of agricultural land. Although these landfills are designed for anti-seepage and ventilation in accordance with established specifications, with the increase in the age of landfills and improper maintenance, methane leaks into surrounding farmland have occurred repeatedly. Methane, as a colorless and odorless greenhouse gas, not only has a long-term impact on the climate, but also poses a hidden threat to farmland soil ecosystems, and its impact cannot be ignored.
1. Methane threats to farmland soil ecosystems
Methane, as a byproduct of anaerobic decomposition of organic matter, has a certain degree of toxicity. When it continues to infiltrate from the landfill and diffuse into farmland soil, it will cause the oxygen content in the soil to decrease, affecting the diversity and balance of soil microorganisms. On the one hand, methane will stimulate the reproduction of specific methanogens and inhibit the activities of beneficial microorganisms such as nitrogen-fixing bacteria; on the other hand, the low oxygen environment will also destroy the normal respiratory function of the root system and affect the water and nutrient absorption of crops.
A farmland in central Illinois, USA, encountered a similar problem. As it is separated from the old landfill by a small river, the surface soil methane concentration in the area increases significantly during the hot summer season as river water infiltrates and soil migrates, causing corn root rot, premature plant aging, and a drop in per-acre yield of more than 30%. Subsequent tests showed that in areas where the methane concentration in the soil is above 0.5% by volume, the activity of plant roots is significantly reduced.
2. High-precision methane detection: the premise of protecting farmland around landfills
To effectively deal with the erosion of methane on farmland, the first step is to accurately and quickly identify the path and impact range of methane leakage. This is inseparable from highly sensitive methane detection technology. Traditional soil sampling and testing often have time lags and are difficult to cover large areas of farmland. The methane detector based on TDLAS (tunable laser absorption spectroscopy) technology can quickly scan and obtain real-time gas concentration data on site.
This equipment is usually lightweight and can be deployed on handheld terminals, tripods, agricultural inspection vehicles, and even agricultural drones. Its high-precision detection capability supports a sensitivity of 5ppm·m, can identify tiny changes in methane concentration, and generate concentration heat maps with the assistance of the GPS system, providing spatial distribution references for land managers.
More importantly, the TDLAS methane detector does not need to directly contact the soil, and uses the reflection principle of the laser beam for remote sensing, avoiding the interference of traditional detection on crops, and is particularly suitable for non-destructive monitoring during the crop growth period.
3. Practical application of monitoring data in agricultural management
With real-time methane concentration data, agricultural managers can formulate more targeted farming plans. Taking the Illinois case as an example, local agricultural consultants delineated a “high-risk buffer zone” based on the detection layer, and recommended that farmers plant moisture-resistant and hypoxia-resistant crops (such as rye and alfalfa) in the area, and arrange deep plowing operations before seasonal rainfall to help soil ventilation and reduce methane accumulation.
In addition, combined with the built-in data interface of the detector, relevant departments can also upload the collected concentration data to the agricultural information platform to realize the correlation analysis of gas emissions and crop yields, so as to conduct dynamic evaluation. Long-term data accumulation can also be used to monitor soil quality trends, providing a basis for land asset valuation and ecological compensation.
4. Technology extension and future prospects
With the promotion of the concept of precision agriculture, methane detection is gradually transforming from “environmental monitoring” to an important tool for “agricultural decision-making”. Some developed countries have begun to explore the “farmland-landfill joint monitoring area” model: multiple departments such as environmental protection, agriculture and geology jointly build regional gas monitoring systems, and improve monitoring accuracy and response efficiency through fixed sites and mobile devices.
At the equipment level, methane detectors are also developing towards intelligence. For example, detection terminals equipped with AI algorithms can automatically identify abnormal concentration changes and issue warnings; and the new generation of embedded communication modules realize real-time docking of data with agricultural meteorological systems, making risk forecasts more accurate.
5. Conclusion: Farmland protection cannot be separated from scientific and technological support
The “invisible boundary” between landfills and farmland is often blurred due to methane leaks. Without timely and effective monitoring methods, the soil ecosystem is likely to be damaged unknowingly, ultimately affecting food output and farmers’ livelihoods. The popularization of high-precision methane detectors is the key to breaking this invisible crisis. It not only helps us see invisible risks, but also provides a scientific basis for the restoration and protection of farmland ecology. In future agricultural management, it is expected to become a must-have tool for every land guardian.
