Canada’s Beef Cattle Research Council (BCRC) has funded several multi-year studies examining how the nutrients in distiller’s dried grains with solubles (DDGS) impact manure, according to Ethanol Producer magazine. The research indicates that increased phosphorous and nitrogen levels will require feedlots to spread the manure over greater land base to avoid negatively impacting soil quality.
Studies were carried out by researchers at the University of Guelph in Ontario, the University of Saskatchewan and Agriculture and Agri-Food Canada’s Lethbridge Research Center in Alberta.
Diets containing varying amounts of DDGS derived from corn and wheat were fed to feeder steers or heifers weighing 925 to 1050 lb., during a three-week periods. The nutrient content of the manure, specifically nitrogen and phosphorous, was compared to a control group after each feed rotation period. Because there is no starch in distiller's grains, researchers were not surprised to find that the nitrogen and phosphorous contents in manure resulting from DDGS diets were higher. However, they also found that as the amount of DDGS is increased in cattle diets, there is a point at which the animal does not absorb any more of the nutrient, thus even greater amounts are excreted. Distiller’s grains are less digestible than feedgrain so the amount of manure produced is greater than corn. More concentrated manure means a larger land base is required to spread the manure, he says.
The amount of phosphorous and nitrogen that can be applied to land varies by province in Canada, so some feedlots may face stricter regulations than others. And, the nitrogen-to-phosphorous ratio is less than optimal in manure, which could lead to a build-up of phosphorous in the soil if manure is applied to meet a crop’s nitrogen needs, Bergen adds.
Depending on how far a feedlot has to haul the manure, feedlots could reach a point at which the price they are willing to pay for DDGS is impacted, according to Bergen. Regional regulations and enforcement will likely play a role in determining the land base requirements. Ongoing studies are being conducted to further test nutrient content of DDGS-derived manure, comparing fresh to composted manure and evaluating its performance on various soil types. Read more about the research at http://www.ethanolproducer.com/articles/8369/studies-evaluate-impact-of-nutrients-in-ddgs-manure .