236-8 Root, Residue and Removal-C and -N Pools Compared to Above Ground Production for Forage-Based Management Practices.



Tuesday, October 18, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Vern S. Baron, Plant and Soil Section, Agriculture and Agri-Food Canada, Lacombe, AB, Canada, Reynald L. Lemke, Soil Science, Agriculture and Agri-Food Canada, Saskatoon, SK, Canada, John A. Basarab, Alberta Agriculture and Rural Development, Lacombe, AB, Canada and Alan Iwaasa, Semiarid Prairie Agricultural Research Center, Agriculture and Agri-Food Canada, Swift Current, SK, Canada
Sustainable forage-based management practices should have high above ground production (AGP) and leave high quantities of root and residue C and N in the ecosystem. The objective was to compare hay and pasture systems with an old grass (OG) baseline on the basis of C and N pools of above ground residue, roots, harvested removals and AGP (removal plus residue). The OG baseline was treated as hay with no inputs; other treatments were: fertilized-N barley silage (FB); 3 yr-old meadow bromegrass (MB) hay and pasture, each with control, alfalfa mixture and fertilized-N sub-treatments. All parameters were subjected to ANOVA. A bi-plot analyses was conducted between AGP-C and root plus residue (RR)–C and AGP-N and RR-N to determine the best system combinations of high AGP and RR retained in the ecosystem for C and N pools. Pasture systems had half the C-removals and twice the residue-C levels as hay systems. Pastures returned greater than 90% of AGP-N to the residue pool. The pasture MB-alfalfa mixture was identified as having high AGP and high RR for both C and N pools. The OG and pasture controls had low AGP, but high RR-N and RR-C. The OG had high root-C and N, but low AGP.  The FB had high AGP, but low RR-C and -N values due to high removals and very low root- C and -N pools. For MB hay and pasture systems fertilizer-N and alfalfa mixture tended to increase AGP and residues over controls. At completion the study will determine greenhouse gas emissions for systems expressed on an AGP basis.
See more from this Division: C06 Forage and Grazinglands
See more from this Session: Forage Ecology and Physiology