Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2006
Publication Date: 3/15/2006
Citation: Cusick, P.R., Powell, J.M., Kelling, K.A., Hensler, R.F., Munoz, G.R. 2006. Dairy manure nitrogen mineralization estimates from incubations and litterbags. Biology and Fertility of Soils. DOI 10.1007/s00374-006-0071-z. Interpretive Summary: Estimates of dairy manure nitrogen (N) availability for crop use are difficult to make. Manure is a mixture of urine, feces and bedding and each component may decompose differently in soil. To assist in the prediction of manure N availability for crop uptake, a laboratory trial was conducted to determine the relative mineralization of urine, feces and bedding components of dairy manure after application to a silt loam soil. During the 168 days following manure application to soil, 14 to 19% of N in feces and bedding, and 50 to 60% of the N in urine was converted to plant available (ammonium plus nitrate) N. A field trial showed that during the 154 days following manure application, approximately 67% of total manure N decomposed in soil. These trials show the importance of conserving urine N, the dairy manure N component most readily available for crop use.
Technical Abstract: A laboratory incubation trial and a field litterbag study were conducted to determine the rate and magnitude of 15N labeled and unlabeled dairy urine, feces, and straw bedding decomposition in a south central Wisconsin silt loam soil. Dairy manure components were incubated with soil at 11, 18, or 25ºC and samples were taken at 14, 21, 42, 84, and 168 days thereafter and analyzed for mineralized N (ammonium- plus nitrate-N) and 15N abundance in the inorganic and organic fraction (only at day 168). Nylon mesh (38 µm) litter bags filled with 15N labeled manure (2000) or unlabeled manure (2002) were placed 7.5 cm below the surface and excavated at 7, 14, 21, 28, 35 (2000 only), 42, 56, 84, 98, 126 days after burial and at corn (Zea mays L.) harvest, 142 days in 2002 and 154 days in 2000. In the incubation study, 50 to 60% of applied urine N was mineralized showing the importance of this manure N component as a source of plant available N. About 14 to 19% of applied N mineralized from fecal and bedding components. In the litterbag experiment, approximately 70% of the dry mass and 67% of the N was released from the litterbags with similar amounts measured using either labeled of unlabeled N. Rates of organic matter decomposition and N mineralization were best predicted using single exponential models for both years with most of the release occurring in the first 21 days.