After the optical frequency comb made its debut as a ruler for mild, spinoffs adopted, together with the astrocomb to measure starlight and a radar-like comb system to detect pure gas leaks. And now, researchers have unveiled the “agricomb” to measure, ahem, cow burps.
The agricomb might assist optimize agricultural processes to scale back manufacturing of heat-trapping greenhouse gases.
Researchers from the National Institute of Standards and Technology (NIST) and Kansas State University (KSU) used NIST’s agricomb to concurrently measure emissions of methane, ammonia, carbon dioxide and water vapor from the ambiance round a beef cattle feedlot in Kansas. The NIST equipment — a two-comb system — identifies hint gases primarily based on the precise shades and quantities of infrared mild absorbed by the ambiance when the comb mild is shipped forwards and backwards throughout open-air paths.
Described in Science Advances, the demonstration was the primary use of frequency combs in an agricultural setting. The transportable system was arrange inside a trailer parked subsequent to the feedlot. The laser mild was specifically amplified and filtered to focus on particular gases.
Researchers measured gases alongside two 100-meter paths each upwind and downwind from pens containing about 300 cows. The experiment targeted on methane and ammonia as a result of emissions from livestock, primarily cattle, are the biggest U.S. supply of anthropogenic methane, a serious greenhouse gas, and ammonia is a crucial atmospheric pollutant.
The measurements captured emissions from each the cattle’s digestive processes and manure on the bottom. The agricomb measured each methane and ammonia concentrations at parts-per-million ranges with a precision of 25 components per billion. The agricomb outcomes for methane have been similar to these from a business sensor that sampled the air at multiple inlets alongside the perimeters of the feedlot. The comb system was notably helpful for ammonia as a result of this gas is sticky and troublesome to measure with inlet-based methods. In addition, the agricomb can measure many gases concurrently, which is difficult for typical methods.
Finally, whereas the business sensors measured exact background ranges sooner, the agricomb extra exactly captured downwind plumes and will then higher characterize the gas sources, in keeping with the paper. The elevated precision can be crucial for deliberate future measurements of methane from sparsely distributed cows in a pasture, which is a way more difficult downside.
The settlement of the previous and new strategies evokes confidence that the agricomb can be utilized to precisely quantify gases in agricultural contexts, the paper suggests. Advantages of the agricomb embrace sensitivity to a broad vary of infrared mild, excessive precision, calibration-free detection of multiple gases without delay, and suppleness of the measurement setup. Pairing two combs with completely different spacings of “teeth” for figuring out precise colours of sunshine makes the evaluation extra exact.
Estimating methane emissions from livestock is difficult due to variations in administration practices and cattle traits in business farms. In addition, what the cattle eat impacts emissions however is unaccounted for in nationwide inventories, resulting in massive uncertainties in greenhouse gas emission fashions, in keeping with the paper. The cattle on the Kansas feedlot ate a mixture of hay and corn silage.
“For the future our plan is to work with KSU to do a pasture measurement, where the cattle eat native grasses,” NIST physicist Brian Washburn mentioned. “The different feed, plus microbial activity in grassland soils that consumes methane, may mean less atmospheric methane production in the pasture than in the feedlot. The cattle spend about 75% of their life in the pasture, so this measurement would be more representative of the net methane production. This would also be a harder measurement, since it would take place over a larger area, about 500 meters by 500 meters, with fewer animals, about 40 head.”
The researchers counsel the agricomb can help precision agriculture — the usage of new know-how to spice up yields — by measuring many gases concurrently over massive spatial scales, making it attainable to design cleaner and extra productive farms.
This work was funded partially by the National Science Foundation, the ARPA-E MONITOR program, the William and Joan Porter Endowment, and the Habiger Heritage Fund.