Poster Number 547
Tuesday, 7 October 2008
George R. Brown Convention Center, Exhibit Hall E
Throughout the years, no-tillage (NT) systems prove to have many benefits. These benefits include increase surface soil organic matter (SOM), improved soil aggregation, high soil water content, decreased risks of soil erosion, and reducing greenhouse emission (especially carbon dioxide, CO2). Long-term NT could have some disadvantage (such as pathogens and weeds). Some studies suggest that one or a few tillage operation could help reduce pathogens and/or weed populations. This study is concerned with the changes that a single tillage operation after many years of NT has on CO2 gas flux and soil water content. In 2004, the CO2 flux experiment was initiated on a farmer’s field that has been under no-till management for 12 years. The treatments include: (i) conventional tillage (CT) for 4 growing seasons; (ii) NT for the first season and CT for the next 3 growing seasons; (iii) NT for 2-growing seasons and CT for the next 2 growing seasons; and (iv) NT for 3 growing seasons and CT for one growing season. In 2004, the CO2 flux was 70% grater with the 1st time tillage than with no-tillage (NT) especially during the first 2 seconds after running a v-blade sweep in the surface 10 cm of soil. While the CO2 flux was only 40% greater than NT with the treatment that was tilled for the second year (in 2005). After 1 hour of tillage, CO2 flux with both tillage treatments (1st and 2nd year tillage) was almost the same and it was greater than NT by 55%. At the 24 hour to 4 week period, the CO2 flux was positively affected by soil water content (SWC). Greater SWC after 2 weeks of tillage increase CO2 flux by more than 37% with tillage treatments compare with NT. This increase could be due to SOM decomposition which was promoted by tillage practice. No-tillage showed 80% less CO2 flux and 11% greater SWC compared with both tillage treatments even after 4 weeks of measurement.