Submitted to: Agronomy Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 11/3/2004
Publication Date: 11/3/2004
Citation: Mikha, M.M., Rice, C.W. 2004. Aggregate carbon and nitrogen dynamics during laboratory incubation. Agronomy Abstracts. Presented at the American Society of Agronomy Annual Meeting. Nov. 2-6, 2004. Denver, Colo. Interpretive Summary:
Technical Abstract: Soil aggregation protects soil organic matter (SOM) against microbial decomposition. We examined the effect of long-term (10 yr) tillage (no-tillage (NT), conservation tillage (CT) and N sources (manure (M), and NH4NO3 fertilizer (F)) on soil aggregate stability and SOM dynamics during laboratory incubation. Aggregate dynamics were studied a laboratory incubation (328 days). Subsamples were separated into four aggregate size classes (20-53, 53-250, 250-2000, and <2000 micron) by wet sieving 7 times during the incubation for aggregate size distribution and aggregate-associated C and N. At the end of the incubation (328 d), the mass of microaggregates (250-2000 and >2000 micron) decreased, while the mass of microaggregates (53-250 micron) increased by more than 50% for M and F while the mass of microaggregates (20-53 micron) significantly increased 32% and 9% for M and F, respectively. Aggregates >2000 micron from NT conserved total C and N for a longer period during the incubation than from CT. The >2000 micron aggregates from CT disaggregated after 114 and 56 days for M and F, respectively. In general, NT had greater macroaggregate stability and aggregate-associate C and N compared with CT. The combination of NT and M further improved aggregate stability and C and N conservation.