ARS | Publication request: AGGREGATE ASSOCIATED CARBON, NITROGEN, AND PHOSPHORUS DYNAMICS

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: June 18, 2005
Publication Date: November 7, 2005
Citation: Green, V.S., Dao, T.H., Cavigelli, M.A., Flanagan, D.C. 2005. Aggregate associated carbon, nitrogen, and phosphorus dynamics [abstract]. American Society of Agronomy Meetings [CDROM]. Poster No. 285-17.

Technical Abstract: During a soil erosion event, water-soluble forms of C, N, and P can move with runoff while complexed forms of C, N, and P can move with suspended sediments and colloids. Previous studies on this soil type have shown that concentrations of C, N, and P vary among aggregates of different sizes with greater concentrations in macroaggregates than microaggregates. Soil samples (0-5 cm) from a no-till (NT) cropping system and was separated into five aggregate size classes from less than 0.05 to greater than 2 mm by wet sieving. Aggregate samples were incubated at 25 C at 60% WHC for 56 days. Headspace was sampled regularly to measure CO2 evolution; soil samples were taken from the incubation vessels periodically to measure water extractable P (WEP), EDTA-extractable P (EDTA-P), and EDTA- phytase hydrolysable P (EDTA-PHP), representing labile and complexed inorganic and organic bioactive P forms. Soil samples were also analyzed for NO3- to determine N-mineralization rates. Cumulative CO2 evolution and N-mineralization were greatest in the macroaggregates sizes. Concentration of P in the different P-fractions was greater in macroaggregates, but a shift among P-fractions over time was observed. These data represent the fate of C, N, and P in the different aggregate sizes.