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Nitrogen Transformations and Microbial Population Dynamics in Soil Amended with Fermentation Residue
Author(s) -
Volz M. G.,
Heichel G. H.
Publication year - 1979
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1979.00472425000800030033x
Subject(s) - loam , population , growing season , residue (chemistry) , agronomy , denitrifying bacteria , chemistry , dry weight , zoology , fermentation , soil water , nitrogen , biology , denitrification , ecology , food science , organic chemistry , sociology , biochemistry , demography
To evaluate the fate of N in an agricultural soil treated with an N‐rich industrial byproduct, fermentation residue was applied to Yalesville fine, sandy loam at a loading rate of 75 dry metric tons/ha, or 2,130 and 1,780 kg N/ha during 1975 and 1976, respectively. Treated and control plots were planted to soybeans ( Glycine max L. Merr.) each year. The treated plots yielded 4,350 kg/ha of soybean grain compared with 3,600 kg/ha for the controls in 1975, and 4,100 kg/ha compared with 3,700 kg/ha in 1976. Yield enhancements attributable to fermentation residue application were significant ( P = 0.05) each year despite the severe repression of nodulation on treated plants compared with controls. During the growing season, NO 3 − ‐N accumulations >80 µ g/g oven dry soil were observed in the top 5 cm of treated soil, compared with accumulations of 15 µ g/g or less in the control. Further, elevated NO 3 − ‐N levels were observed in the top 91 cm of treated soil throughout the fallow and growing seasons, when compared with control plots, suggesting that some of the applied N may have been transported to the water table as NO 3 − . Populations of five physiological groups of microorganisms closely mirrored soil levels of NO 3 − ‐N and NH 4 + ‐N in both experiments. Denitrifying bacteria reached population densities of 3.0 × 10 9 /g oven dry treated soil compared with a maximum of 6.8 × 10 5 /g for control soil during the growing season. Enhanced N transforming activity by microorganisms in soil receiving fermentation residue compared with the control soil was supported by the elevated populations of NH 4 + and NO 2 − oxidizing bacteria, and NO 3 − reducing‐, denitrifying‐, and heterotrophic aerobic bacteria observed throughout the fallow and growing seasons. Although application of fermentation residue significantly increased soybean yields, the limited recovery of added N by the crop and the likelihood of substantial N losses suggest a reassessment of application rates or efforts to stabilize N applied to soils from fermentation residues.