Submitted to: American Society of Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2003
Publication Date: November 2, 2003
Citation: Griffin, T.S., He, Z., Honeycutt, C.W. 2003. Transformation of dairy manure nitrogen fractions to plant available forms. American Society of Agronomy Abstracts. Technical Abstract: Differences in the inorganic nitrogen (N) and soluble N (SON) content of dairy manures continue to make prediction of plant available N (PAN) difficult. A 150 d incubation experiment examined changes in soil N following application of 11 different dairy manures, containing a wide range of ammonium (NH4-N) and SON. Manures were applied to moist soil at a rate equivalent to 100 mg organic N/kg soil, and soil NH4 and nitrate (NO3-N) concentration were determined at 0, 3, 7, 14, 28, 56, 108, and 176 d after application. Soil moisture was maintained at 65% of water filled pore space, and samples were stirred and repacked at each sampling date. For manures containing significant NH4, the dominant N transformation was nitrification, indicated by accumulation of NO3 over time. As expected, manures containing higher amounts of carbon (as bedding) either immobilized N in the short-term, or exhibited no net nitrification or immobilization. The amount of NO3 accumulated during the incubation was most strongly related to the amount of NH4 applied. There was little indication that significant net mineralization of manure SON or of more recalcitrant organic N fractions occurred during the incubation, even though conditions were optimal for mineralization.