McConkey, B.G.Lemke, R.Wang, H.Selles, F.2018-08-062018-08-062005-02-17http://hdl.handle.net/10388/9493The long-term practice of no-till (low-disturbance direct seeding) is an effective method to increase the soil organic matter (SOM) content of the soil. If that increased soil organic matter is traded as an offset for greenhouse-gas emissions, then we need to know what happens to SOM if, for whatever reason, the soil is tilled. The results in southwestern Saskatchewan indicated that if the land is cropped, there is evidence of large losses of SOM from single tillage on long-term (13-yr) no-till on sandy loam soil but little loss of SOM on a loam and clay soil from single tillage of long-term (23-yr and 13-yr) no-till. However, if the land was summerfallowed, there were large losses of SOM. As the pioneers discovered when they broke the land, we also found that the faster the SOM is decreased, the greater the release of nutrients, especially nitrogen (N), from SOM. Through this release of N, summerfallow on long-term continuously cropped notill increased the release of the potent greenhouse gas, nitrous oxide (N2O).enAttribution-NonCommercial-NoDerivs 2.5 CanadaPoster Presentation