Effect of water table management and elevated CO on radish productivity and on CH and CO fluxes from peatlands converted to agriculture.

Anthropogenic activity is affecting the global climate through the release of greenhouse gases (GHGs) e.g. CO and CH. About a third of anthropogenic GHGs are produced from agriculture, including livestock farming and horticulture. A large proportion of the UK's horticultural farming takes place on drained lowland peatlands, which are a source of significant amounts of CO into the atmosphere. This study set out to establish whether raising the water table from the currently used -50cm to -30cm could reduce GHGs emissions from agricultural peatlands, while simultaneously maintaining the current levels of horticultural productivity. A factorial design experiment used agricultural peat soil collected from the Norfolk Fens (among the largest of the UK's lowland peatlands under intensive cultivation) to assess the effects of water table levels, elevated CO, and agricultural production on GHG fluxes and crop productivity of radish, one of the most economically important fenland crops. The results of this study show that a water table of -30cm can increase the productivity of the radish crop while also reducing soil CO emissions but without a resultant loss of CH to the atmosphere, under both ambient and elevated CO concentrations. Elevated CO increased dry shoot biomass, but not bulb biomass nor root biomass, suggesting no immediate advantage of future CO levels to horticultural farming on peat soils. Overall, increasing the water table could make an important contribution to global warming mitigation while not having a detrimental impact on crop yield.