|Fortuna, Ann Marie|
|Larkin, Robert - Bob|
|Torbert, Henry - Allen|
|Powell, J Mark|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2011
Publication Date: 11/16/2011
Citation: Fortuna, A., Honeycutt, C.W., Marsh, T.L., Griffin, T.S., Larkin, R.P., He, Z., Sistani, K.R., Albrecht, S.L., Woodbury, B.L., Torbert Iii, H.A., Powell, J.M., Hubbard, R.K., Eigenberg, R.A., Wright, R.J. 2011. Links among nitrification, nitrifier communities and edaphic properties in contrasting soils receiving dairy slurry. Journal of Environmental Quality. 41:262-272. Interpretive Summary: A significant portion of the manure generated in the U.S. is not recycled to cropland. Current nutrient excesses need to be reduced through the incorporation of more accurate predictive measures of manure N availability in land use management guidelines. New research is needed to incorporate soil type and microbial community processes into N availability indices. Nmin is a nationally coordinated laboratory and field research project conducted by a team of USDA-ARS scientists to develop predictions of manure N availability. The inclusion of soils from varying climatic regions enabled us to assess which chemical and physical characteristics of a given soil had the strongest influence on N cycling and nitrification. The quantity and type of clay minerals present in a soil was the single most important factor in determining the quantity of inorganic N present in manured and unmanured managements. Manure applications doubled or tripled nitrification potentials on all soils except the Brooksville Vertisol. Soils with a history of high N inputs and buffering capacity had greater potential nitrification rates. Soils with low N inputs showed the greatest increase in nitrification rate with manure addition. Determining variations in the timing and release of N from manure can reduce loss of manure N and improve best management practices. Manure applications should be adjusted to reflect a soil capacity to nitrify.
Technical Abstract: Nitrogen (N) availability from animal manure is affected by various soil-related biotic and abiotic factors. Predictions of manure N availability must therefore account for the influence of soils on processes controlling N turnover. In this study, a range of soils were collected from six USDA-ARS research sites and used in a 28 d incubation with and without dairy slurry (Bos taurus) amendment applied at a rate of ~300 kg N ha-1. Sub-samples were removed at multiple intervals for analyses of 2 M KCl extractable N and measurement of nitrification potential. The 28 d incubation provided information on short-term decomposition of dairy slurry N and its contribution to plant available N. Nitrification potential proved to be a sensitive indicator of soil related factors and manure management. Soils containing 20 to 30% clay and 15 to 20% sand had the highest nitrification rates (10 - 11 mg N kg-1 soil d-1) when unamended. Nitrification potentials in manure amended soils ranged from 2.6 to 20 mg N kg-1 soil d-1. Manuring doubled or tripled nitrification potentials on all soils except a Vertisol. Soils with a history of high N inputs and levels of total soil N and C had greater potential nitrification rates. Soils with low N inputs showed the greatest increase in nitrification rate with manure addition. This research showed that quantity and type of clay minerals present in a soil were the most important factors influencing nitrification potential. It also follows that manure applications should be based not only on crop N demand, but also on the given soil’s capacity to nitrify.