Gas Flux in Tillage Field That Have Been in No-Tillage for 12 Years (GRACEnet).

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 1^st 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 (1^st and 2^nd 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.