Raising Water Table Depth on Peatlands and Impacts on Grazing Herds Welfare

Peatlands restoration is a mitigation action of importance in the fight against climate change. Researchers encourage agriculture sector stakeholders to rewet deep-drained lands on organic soil to a shallow water table to eliminate ongoing carbon emissions while keeping farming activities. Raising water table depth under grasslands will likely affect local temperature and increase air humidity, with uncertain consequences during heat waves on cattle welfare.

Air temperature and relative humidity were collected from a selection of peatlands involved in meteorological research and in temperate and continental climates through seasons, with varying water table levels. We compared them with the same variables, collected on neighbouring lands on non-organic soil to evaluate the impact of water level depth.

Peatlands with shallow water levels had lower air temperatures and higher relative humidity than surrounding lands on average, compared to those with deep water tables. The overall Temperature Humidity Index (THI), a cattle welfare indicator used in dairy farms, decreased, especially at night in the temperate region, except for coastal peatlands. Variations from deep to shallow water table did not significantly affect the length of time with THI above stress thresholds; however, this time decreased at submerged lands. Our results suggest that increasing water table depth on drained peatlands, as advised by researchers, will slightly improve cattle welfare with reduced THI during heat waves. It also indicates that raising it to ground level in sections of grasslands could provide “heat waves shelters” and increase cattle resilience while contributing to the global reduction of carbon emissions.