Рубрики:
AMMONIA DIFFUSION METHOD
NITROGEN ISOTOPES
ORGANIC-MATTER
NITRATE
CARBON
LAND
TRANSFORMATIONS
ADAPTATION
DELTA-N-15
TURNOVER
AMMONIA DIFFUSION METHOD
NITROGEN ISOTOPES
ORGANIC-MATTER
NITRATE
CARBON
LAND
TRANSFORMATIONS
ADAPTATION
DELTA-N-15
TURNOVER
Аннотация: The availability of C and N to the soil microbial biomass is an important determinant of the rates of soil N transformations. Here, we present evidence that changes in C and N availability affect the N-15 natural abundance of the microbial biomass relative to other soil N pools. We analysed the N-15 natural abundance signature of the chloroform-labile, extractable, NO3-, NH4+ and soil total N pools across a cattle manure gradient associated with a water reservoir in semiarid, high-desert grassland. High levels of C and N in soil total, extractable, NO3-, NH4+ and chloroform-labile fractions were found close to the reservoir. The delta N-15 value of chloroform-labile N was similar to that of extractable (organic + inorganic) N and NO3- at greater C availability close to the reservoir, but was N-15-enriched relative to these N-pools at lesser C availability farther away. Possible mechanisms for this variable N-15-enrichment include isotope fractionation during N assimilation and dissimilation, and changes in substrate use from a less to a more N-15-enriched substrate with decreasing C availability.
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Держатели документа:
No Arizona Univ, Dept Biol Sci, Flagstaff, AZ 86011 USA
RAS, Inst Forest SB, Krasnoyarsk 660036, Russia
No Arizona Univ, Colorado Plateau Stable Isotope Lab, Flagstaff, AZ 86011 USA
No Arizona Univ, Sch Forestry, Flagstaff, AZ 86011 USA
No Arizona Univ, Merriam Powell Ctr Environm Res, Flagstaff, AZ 86011 USA
Доп.точки доступа:
Dijkstra, P...; Menyailo, O.V.; Doucett, R.R.; Hart, S.C.; Schwartz, E...; Hungate, B.A.