Nitrogen Immobilization and Mineralization Kinetics of Cattle, Hog, and Turkey Manure Applied to Soil

Nitrogen mineralization and immobilization following manure application are critical processes influencing plant N supply and offsite N losses. We conducted laboratory experiments to examine the influence of these two processes in addition to N oxide gas production on N availability for 180 d following manure addition. A Tara loam (fine‐silty, mixed, superactive, frigid Aquic Hapludoll) and a Webster clay loam (fine‐loamy, mixed, superactive, mesic Typic Endoaquoll) amended with liquid dairy ( Bos taurus ) manure (LD) were incubated at 25 and 10°C, while Tara soil amended with solid dairy manure (SD) and turkey ( Meleagris gallopavo ) manure (T), and Webster soil amended with liquid hog ( Sus scrofa ) manure (H), were incubated at 25°C. Maximum net N immobilization was 14 and 40% of the initial NH 4 + concentration in H and LD, respectively, and persisted for 35 to 180 d. In LD‐, H‐, and T‐amended soils, net manure N mineralization was not apparent, and there was good agreement between initial NH 4 + content and available inorganic N from the manure. These data suggest that, for these manure types, estimates of first‐season available N would be improved by measuring manure NH 4 + In contrast, in soil amended with SD, which had the lowest initial NH 4 + content, 22% of organic N was mineralized. Gaseous N losses were <1% of the added N in all treatments. The previously developed model NCSOIL was used to predict plant N availability and NO 3 − leaching potential with various manure incorporation dates. Under climate conditions typical of the Upper Midwest, no clear advantage of late fall compared with spring incorporation of manure with regard to N availability could be shown, but NO 3 − leaching potential seemed high with early fall incorporation.