Making renewable natural gas from manure and agricultural residue could make farmers more money, farming more sustainable and – based on a new long-term, on-farm study by Iowa State University researchers – farmland soil richer in carbon.
Digestate, the byproduct of using anaerobic digestion to turn biological matter such as corn stalks and cattle manure into fuel, can boost soil organic carbon levels when applied to fields, according to an analysis of 12 years of data collected on a farm in southeast Iowa where digestate has replaced nearly all of the synthetic nitrogen fertilizer on corn fields.
Researchers studying anaerobic digestion’s potential benefits have expected digestate to be a valuable fertilizer and soil amendment, but there are few studies of how the slurry-like product affects soil organic carbon on a commercial-sized farm, said agronomy professor Fernando Miguez, co-author of the study recently published in the Journal of Agriculture and Food Research.
“Smaller studies don’t necessarily translate to the commercial level,” Miguez said. “But now we’ve shown that this practice can be successful at a scale that matters.”
Source : iastate.edu