2. Jerry Didur Prairie Fire 1992

3. Every year it is estimated that 800 000 000 tons (0.8 Pg) of C are released due to agriculture (Schlesinger, 1995). In Canada, since cultivation of croplands began, approximately 25 % of the C originally present in the A horizon has been lost, 1.1Pg of C, released as CO 2 (Hengeveld, 2008).

4. Louis-Pierre Comeau Professor Angela Bedard-Haughn Quantity and Fate of Carbon Rhizodeposition in Lentil, Pea, Canola and Wheat

5. What is Rhizodeposition and why it’s important Rhizodeposition: release of organic compounds from roots to soil Microbial activity Nutrient cycling Soil organic matter dynamic Pedogenesis GHGs emission/sequestration Exudates Secretions Root cells, Root fragments

6. Rhizodeposition Up to 20% of photosynthetically fixed C is exudated by the roots Exudates: NH 4 + NO 3 - Carbohydrates Amino acids Organic acids 65-85% exudates is rapidly respired by microorganisms Wheat roots produce ~2300 kg C ha -1 / growing season 56-64% organic input to soil is produced by rhizodeposition Clayic soils retain more exudates than sandy soils

7. Questions & hypotheses In which SOM pool rhizodeposits are going? Is there some effect of soil type on rhizodeposition? Is there some crop effect on rhizodeposition?

8. Objective The aim of this study was to evaluate the quantity and destiny of newly produced soil organic C captured at the end of a single growing season of canola (Brassica napus), lentil (Lens culinaris), pea (Pisum sativum) wheat (Triticum aestivum) in two prairies ecoregion.

9. Study sites

10. 13 CO 2 13 C-SOM 2 hours labeling / week 8 weeks 33% 13 C enrichment 380 ppm CO 2 Dissolved organic matter 0-1 g/ml light fraction 1-1.7 g/ml light fraction >1.7 g/ml heavy fraction Fulvic acid humic acid Humin sand Humin clay Method

11. Results & discussion

16. Likelihood to have the highest 13 C enrichment in soil fraction

17. Further studies: 10-20 cm 13 C enrichment 2 sd grow season Estimation total new C produce by hectares by year

18. Acknowledgements Special thanks to James Hnatowich

19. soil typepH% C% clayCEC (cmol c *kg -1 ) AAFC ScottOrthic Dark Brown Chernozem5.73.42821 AAFC Swift CurrentOrthic Brown Chernozem6.422219