TY - JOUR
T1 - Amino acid, peptide and protein mineralization dynamics in a taiga forest soil
AU - Jones, David L.
AU - Kielland, Knut
PY - 2012/12/1
Y1 - 2012/12/1
N2 - The availability of inorganic N has been shown to be one of the major factors limiting primary productivity in high latitude ecosystems. The factors regulating the rate of transformation of organic N to nitrate and ammonium, however, remain poorly understood. The aim of this study was to investigate the nature of the soluble N pool in forest soils and to determine the relative rate of inorganic N production from high and low molecular weight (MW) dissolved organic nitrogen (DON) compounds in black spruce forest soils. DON was found to be the dominant N form in soil solution, however, most of this DON was of high MW of which >75% remained unidentified. Free amino acids constituted less than 5% of the total DON pool. The concentration of NO 3 - and NH 4 + was low in all soils but significantly greater than the concentration of free amino acids. Incubations of low MW DON with soil indicated a rapid processing of amino acids, di- and tri-peptides to NH 4 + followed by a slower transformation of the NH 4 + pool to NO 3 -. The rate of protein transformation to NH 4 + was slower than for amino acids and peptides suggesting that the block in N mineralization in taiga forest soils is the transformation of high MW DON to low MW DON and not low MW DON to NH 4 + or NH 4 + to NO 3 -. Calculated turnover rates of amino acid-derived C and N immobilized in the soil microbial biomass were similar with a half-life of approximately 30 d indicating congruent C and N mineralization.
AB - The availability of inorganic N has been shown to be one of the major factors limiting primary productivity in high latitude ecosystems. The factors regulating the rate of transformation of organic N to nitrate and ammonium, however, remain poorly understood. The aim of this study was to investigate the nature of the soluble N pool in forest soils and to determine the relative rate of inorganic N production from high and low molecular weight (MW) dissolved organic nitrogen (DON) compounds in black spruce forest soils. DON was found to be the dominant N form in soil solution, however, most of this DON was of high MW of which >75% remained unidentified. Free amino acids constituted less than 5% of the total DON pool. The concentration of NO 3 - and NH 4 + was low in all soils but significantly greater than the concentration of free amino acids. Incubations of low MW DON with soil indicated a rapid processing of amino acids, di- and tri-peptides to NH 4 + followed by a slower transformation of the NH 4 + pool to NO 3 -. The rate of protein transformation to NH 4 + was slower than for amino acids and peptides suggesting that the block in N mineralization in taiga forest soils is the transformation of high MW DON to low MW DON and not low MW DON to NH 4 + or NH 4 + to NO 3 -. Calculated turnover rates of amino acid-derived C and N immobilized in the soil microbial biomass were similar with a half-life of approximately 30 d indicating congruent C and N mineralization.
KW - Biodegradation
KW - Boreal forest
KW - Coniferous forest
KW - Dissolved organic carbon
KW - Nitrogen mineralization
UR - http://www.scopus.com/inward/record.url?scp=84864073572&partnerID=8YFLogxK
U2 - 10.1016/j.soilbio.2012.06.005
DO - 10.1016/j.soilbio.2012.06.005
M3 - Article
AN - SCOPUS:84864073572
VL - 55
SP - 60
EP - 69
JO - Soil Biology & Biochemistry
JF - Soil Biology & Biochemistry
SN - 0038-0717
ER -