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Soluble Carbon and Nitrogen Pools of Prairie and Cultivated Soils: Seasonal Variation
Author(s) -
DeLuca T. H.,
Keeney D. R.
Publication year - 1994
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1994.03615995005800030029x
Subject(s) - soil water , mineralization (soil science) , biomass (ecology) , chemistry , nitrogen , organic matter , total organic carbon , nitrogen cycle , environmental chemistry , agronomy , botany , biology , ecology , organic chemistry
Recent evidence indicates that long‐term cultivation of prairie soils reduces the ambient concentrations of soluble amino N and soluble sugars. It is not known whether cultivation has affected how these constituents fluctuate with season. This study was performed to determine if cultivation has affected how soluble sugars, soluble C, and soluble amino N fluctuate with season and whether this fluctuation corresponds with seasonal changes in microbial biomass and extractable N. Soils were sampled bimonthly and analyzed for 0.5 M K 2 SO 4 soluble sugars (anthrone‐reactive carbon [ARC]), soluble organic C, microbial biomass, and 2 M KCl extractable amino N, NH 4 , and NO 3 . Cultivation has clearly reduced the levels of microbial biomass C, soluble ARC, and soluble amino N in these soils. Microbial biomass C was greatest in late February after thaw. Soluble ARC generally was greater in prairie soils than in cultivated soils but did not increase in concert with microbial biomass. Soluble amino N declined when microbial biomass and N mineralization increased in February. The ratio of soluble ARC to NO 3 ‐N indicates that there is generally insufficient C available, as soluble sugars, to allow for immobilization of ambient NO 3 in cultivated soils throughout the course of a year. The high ratio of soluble C to biomass C in cultivated soils may also be evidence of a reduction in organic matter quality as higher levels of soluble C appear to support lower levels of microbial biomass. Cultivation has reduced concentrations of soluble sugars and amino N and has affected how these constituents change with season. However, the relation of soluble sugars and amino N to microbial biomass is not clear.