137-9 Minnesota Soil Survey Sites Revisited: Long-Term Trends In Soil Carbon.



Monday, October 17, 2011
Henry Gonzalez Convention Center, Hall C, Street Level

Deborah Allan1, Karina Fabrizzi1, Keith Piotrowski1, Greg Larson2 and Megan Lennon2, (1)University of Minnesota, Saint Paul, MN
(2)Board of Water and Soil Resources, Saint Paul, MN
Sites in different ecoregions of Minnesota were resampled and analyzed in 2009 and 2010 to compare C concentrations to those from archived soil survey samples stored for 30-40 years. Overall findings of the project show that for 102 sites, mean C concentration had increased significantly for forest soils (+38%) and decreased in cropped soils (-13%) over mean depths of 60-75 cm.  Grassland soil C increases were not significant due to small sample numbers (n=9).  When averaged for each horizon, carbon increased significantly in the top two horizons (0-10 cm and 10-33 cm) at forest sites, while grassland sites had significant increases only in the second horizon (20-41 cm).  Cropland sites had mean decreases of 24% in the surface horizon. Where sites had undergone changes from cropland to grassland, C concentration increased 53% (from 12.2 to 18.8 g C kg-1 soil for 12 sites), but site numbers were too small to see C differences for other management conversions. Regional differences in C changes reflected the predominant managements sampled in each area.
See more from this Division: S06 Soil & Water Management & Conservation
See more from this Session: Agricultural Practices to Increase Nitrogen-Use Efficiency, Carbon Sequestration, and Greenhouse Gas Mitigation : II