Raising the stakes
Although biofuels offer a renewable source of energy, it comes at a cost: the heavily fertilized soils used to grow biofuel crops emit large amounts of nitrous oxide, a potent greenhouse gas. These emissions, produced by microbial processes within the soil, can vary greatly over time and location, making them challenging — and expensive — to measure. To quantify nitrous oxide emissions and devise more climate-friendly farming practices, Ana Claudia Arias and Kristofer Pister, professors of electrical engineering and computer sciences, are working with Whendee Silver, professor of ecosystem ecology and biogeochemistry, to develop a tracking system for agricultural land using a novel printed sensor array and a wireless communications platform.
Their technology, dubbed the SmartStake system, uses stake-mounted sensors to provide an inexpensive alternative to cavity ring-down spectroscopy, a state-of-the-art but far more costly method for measuring gases like nitrous oxide. The simple printed sensors can be easily replaced at the end of a crop’s growing season, enabling the implementation of sensing modalities that would otherwise be impractical. In addition to concentrations of nitrous oxide, nitrate, ammonium and oxygen, the sensor network can measure pH, temperature, moisture and denitrifying microbial enzymes; the resultant data can then be analyzed by a machine learning model. The researchers hope their system may someday transform biofuel agriculture by enabling farmers to fine-tune agricultural practices to lower nitrous oxide emissions, while also optimizing fertilizer and irrigation usage.