Brookings, S.D.-South Dakota State University (SDSU) research suggests that ash left over from producing ethanol can be used as fertilizer. According to Prof. Ron Gelderman, manager of the SDSU soil testing laboratory, it’s the dried distillers grains with solubles, or DDGS, that have the potential. Geldeman explained that the ash material is produced when DDGS is heated at high temperatures under limited oxygen to make synthesis gas for products such as bioplastics and lubricants. That sparked an interest in whether the ash, usually discarded in landfills, could be applied to fields as a soil nutrient. “I think everybody recognizes that if we take off organic material and then utilize it for its energy, we’re going to be removing nutrients and minerals from the soil, and so these really should be put back onto the soil,” Gelderman offered, “or at least placed on soils that need these particular nutrients so we can sustain the soils that we have and not run into problems with low organic matter and lower fertility down the road.” An SDSU greenhouse study found that dried distillers grain ash resulted in about the same increase in corn growth as fertilizer phosphorus. Use of dried distillers grain ash as a source of potassium in that study was inconclusive, since the selected soil supplied adequate plant potassium. However, a separate field study at SDSU showed that DDGS ash was just as effective as fertilizer phosphorus and potassium in providing both nutrients for corn production, Gelderman said. The problem, he added, is physically handling the material, which is very fine and blows in the wind and doesn’t really lend itself to fertilizer spreader-type application. That suggests that further processing of the material – possibly into pellets, as a liquid slurry, or mixed with manure or lime – might be necessary to get it back onto the land.
Transparency Across the Fertilizer Value-Chain