Project Overview
Commodities
- Agronomic: grass (misc. annual), grass (misc. perennial), hay
- Animals: bovine, sheep
- Animal Products: dairy, meat
Practices
- Animal Production: feed/forage, grazing management, rangeland/pasture management
- Education and Training: extension, on-farm/ranch research
Abstract:
Effect of recurring flooding on greenhouse gas emissions, soil C and N contents and forage quality in grazing and hay fields.
Recent rainfall and weather projections show strong evidence suggesting to an increase in the frequency and magnitude of flooding events in the central U.S., because of changes in both seasonal rainfall and temperature across the region. In Ohio, areas prone to recurring short-term flooding are cultivated with perennial forages and make up an important part of the productive area for farms such that increased recurrence of flooding challenges farm productivity. Previous studies suggest that long-term flooding is associated with reduced forage nutritive values and increased stem heights and elongation rates. However, the effects of recurring short-term flooding on forage quality and production remain unexplored. The effects of flooding on greenhouse gas (GHG) emissions also remain underexplored. This project explored flooding effects in the south and north regions of Ohio on forage quality, dry mass production, greenhouse gas emissions, and soil C and N contents. Overall, recurring short-term flooding did not affect forage production in any of the locations, but negatively affects some of the forage quality parameters in the north region. For high-flooding areas, lower forage crude protein and higher neutral detergent fiber were found, while acid detergent fiber, digestibility, and lignin were not affected. Overall, recurring short-term flooding did not consistently increase GHG emissions in any location, rather a tendency to decrease emissions was observed in highly inundated soil in the north region. These findings support the efforts of the Ohio Department of Agriculture Working Lands Buffer Program (WLBP), which supports conversion of flood-prone areas to perennial forages, to reduce nutrient loss. Results of this study indicated that the conversion is also helpful to reduce nutrient loss to air, via greenhouse gas emission, when simultaneously providing high-yielding forage mass. Learning outcomes are the understanding of flooding effects on forage quality and production, which was a question farmers had with the WLBP was launched. We expect that the results will increase farm adoption to the Program. The collaborating farmer in the North Region was happy to share results at the Ohio Forage and Grassland Council meeting, to share with other farmers that the conversion from row crops to forages in the flooded sites was beneficial economically and environmentally.
Project objectives:
The project objective was to understand the effects of flooding on greenhouse gas emissions from soils, C and N contents and forage quality in historically grazed pastures and hay fields, in south and north OH. Originally, in the north region we had proposed to compare flooded forages and crop fields. The objective was modified to evaluate the same parameters but at different levels of flooding intensity and management (historically grazed and hayfields). The reason was that during a farm visit in the North region we observed three different levels of flooded hayfields: non-flood, light flood, and heavy flood. Considering the lack of information regarding effects of flooding on perennial areas, and the interest of the Working Lands Buffer Program (WLBP) in converting croplands to forage lands, we decided to focus sample collection on the different levels of flooding in forage areas. The change was described further in the mid-project report.
To address the problem, I identified pseudo-replicates with naturally occurring flooding in two farms in Ohio. In the south region, pastures had a long-term history of grazing or hay (over 10 years) and were flooded and non-flooded. In the north region, I identified three levels of flooding intensity (non-flooded, low-flooding, and high-flooding), in fields that were converted to hay (from corn-soybeans rotation) as part of the WLBP. In both locations, and throughout the growing seasons of 2021 and 2022, I evaluated forage quality parameters, greenhouse gas emissions from pasture soils, and soil C and N contents.