Miss Marie-Elise Samson1,2,3, Dr. Martin Chantigny2, Dr. Anne Vanasse1, Dr. Safya Menasseri-Aubry3, Dr. Denis Angers2
1Laval University, Québec, Canada, 2Agriculture and Agrifood Canada, Québec, Canada, 3Agrocampus Ouest, Rennes , France
In a unifying framework based on the MEMS model, Robertson et al. (2019) recently suggested that the heavy-particulate OM fraction (composed of litter fragments and microbial residues associated to mineral surfaces) could play an important role in soil nutrient cycling and be a precursor of stable C in soil. Maillard et al. (2015) showed that dairy cattle manure application resulted in a preferential accumulation of C this heavy-particulate OM fraction. Because they contain microbial metabolites, we hypothesized that animal manures in general foster the formation of heavy particulate OM and therefore sustain both C storage and N supply soil functions. We tested this hypothesis using a long-term (9 years) agronomic trial located in eastern Canada. This factorial experiment evaluated the effect of different fertilizer sources (no-N control (PK), complete mineral fertilization (NPK), liquid pig, liquid dairy cattle, and solid poultry manures) on two soil types (silty clay and sandy loam). Soil samples (0-7.5 cm) were collected and fractionated using a size-density method (Maillard et al. 2015). In both soil types, the heavy-particulate OM fraction was the most sensitive to treatments with greater C and N accumulation in that fraction with poultry manure and liquid dairy manure as compared to the NPK and no-N control treatments. In the silty clay, there was also C and N accumulation in the finer and presumably more stable organo-mineral complexes, but not in the sandy loam. We propose that the heavy-particulate OM (i) is a meaningful fraction in terms of nutrient cycling likely linked to manure legacy effect, and (ii) is a precursor to long-term accumulation of stable C and N forms where soil texture allows the formation of finer organo-mineral associations.
Maillard, E. et al. 2015. Agriculture Ecosystems and Environment. 202: 108-119.
Robertson, A.D. et al. 2019. Biogeosciences. 16: 1225-1248.
Biography: Marie-Élise Samson is a Ph.D. student in soil conservation at Laval University (Canada) and Agrocampus Ouest (France) in collaboration with Agriculture and Agri-Food Canada. She was recently granted the prestigious Vanier Canada Graduate Scholarship for her work on soil organic matter in agricultural soils. Together with her group, she studies the effects of different management practices on carbon and nitrogen cycling. In addition to participating in several conferences in France and Canada, she was recently invited as a guest speaker at the Living Soil Symposium held in Montreal in March 2019.