Characterization of Anaerobic Digestates for their Nitrogen Fertility Value and Improved Nutrient Management
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Abstract
The purpose of this research was to determine the nitrogen fertility benefits of anaerobic digestates (AD) applied to agricultural soils for crop production. The kinetics of nitrogen release in soils amended with AD were measured in 6-week laboratory incubation studies. Nitrification occurred within the first 3-4 weeks. Mineralization was not statistically significant over time. Soil samples from field trials in the 2012 - 2013 cropping year showed nitrification and mineralization occurred in the six weeks after AD application. Most soil inorganic-N was taken up by the crop before harvest. Early growth of maize (Zea mays L.) in soil amended with AD was investigated in a greenhouse trial. Field trials in 2012 and 2013 measured grain yield response and stover production of maize in soils treated with AD, urea, or manure (2013 only). These experiments confirm that inorganic-N in digestate and urea is equally available, and that ADs are a comparable nitrogen source to liquid manure (FNEs of 34% and 31%, respectively).