Water‐table management in lowland UK peat soils and its potential impact on CO₂ emission

Abstract

The rate of oxidation of peat soils is highly seasonal and varies with temperature and soil moisture content. Large variations in soil moisture content result in wet–dry cycles that can enhance peat degradation. Water‐table management plays a crucial role in controlling and damping the effect of these environmental factors. However, maintaining high ditch water levels in fields bounded by ditches does not guarantee a high field groundwater level. The effect of installing subsurface irrigation at different spacings on water table elevation was studied in a low‐lying peat grassland. The water table elevation data were compared against values predicted with a water balance model. In addition, greenhouse experiments were carried out on undisturbed soil core samples collected from the peat grassland as well as a low‐lying peatland under intensive arable faming to measure CO2 evolution under different water regimes. The field data from the peat grassland suggest that sub‐irrigation spacing as low as 10 m is necessary during summer periods to maintain groundwater levels similar to those in the ditches. Over the same period of observation, the difference in water level between the ditches and the non‐irrigated fields is as high as 0.7 m. Modelled outputs are in good correlation with the field observations, and demonstrate that simple water balance models can provide an effective tool to study the effect of water management practices and potential changes in subsurface conditions, climate and land use on water‐table levels. The measurement of CO2 emission from undisturbed peat soil columns shows that the rate of oxidation of soil organic matter from peat soils is highly seasonal and that drainage exacerbates the rate of peat mineralization.

Thinning Intensity Affects Soil-Atmosphere Fluxes of Greenhouse Gases and Soil Nitrogen Mineralization in a Lowland Poplar Plantation

“…However, a significant and negative correlation between water table and CO 2 emission was detected in this study (Table 1). This result does not support the observation reported by many investigations, where CO 2 emissions increased following the lowering of the water table level [58]; however, it is in agreement with the results reported in Berglund and Berglund [48] and Kechavarzi et al [59], where CO 2 emission rates were higher in the peat soil with a high water table level.…”

Influence of water table level and soil properties on emissions of greenhouse gases from cultivated peat soil

“…Contrary to our results, many investigations have reported increasing CO 2 emissions following lowering of the groundwater level (Eggelsman, 1976;Renger et al, 2002;Wessolek et al, 2002). Findings supporting our results, with a higher emission rate at intermediate groundwater levels compared with low (dry soil), have been reported by Davidson et al (1998), Chimner and Cooper (2003) and Kechavarzi, C. et al (2007). Nieveen et al (2005) found that the distance to the groundwater did not influence the emission of CO 2 and Aerts and Ludwig (1997) and Maljanen et al (2001) reported similar results.…”

Greenhouse Gas Fluxes from Dutch Peatland Water Bodies: Importance of the Surrounding Landscape

“…Schrier-Uijl et al (2010a) as well as Dias et al (2010) reported higher fluxes (~1 and 0.03 mg CH 4 m −2 h −1 ), but earlier work of suggest that intensively used well-drained grassland is a net sink for CH 4 (−0.003 mg CH 4 m −2 h −1 ). At the same time, these drained peatlands emit substantial quantities of CO 2 and N 2 O, and all should be included when estimating a full greenhouse gas balance (Hendriks et al 2007;Kechavarzi et al 2007;Veenendaal et al 2007). Since water may cover anywhere between 6 and 43% in these peatlands (Vermaat and Hellmann 2010), our findings imply that landscapescale assessments of methane fluxes require separate estimates of terrestrial and aquatic fluxes, where the latter need to take into account productivity and groundwater table (Kechavarzi et al 2007) of the adjacent land.…”

“…At the same time, these drained peatlands emit substantial quantities of CO 2 and N 2 O, and all should be included when estimating a full greenhouse gas balance (Hendriks et al 2007;Kechavarzi et al 2007;Veenendaal et al 2007). Since water may cover anywhere between 6 and 43% in these peatlands (Vermaat and Hellmann 2010), our findings imply that landscapescale assessments of methane fluxes require separate estimates of terrestrial and aquatic fluxes, where the latter need to take into account productivity and groundwater table (Kechavarzi et al 2007) of the adjacent land. We did a tentative landscape-scale estimate using our own aquatic CH 4 fluxes at annual mean temperature, terrestrial estimates from Dias et al (2010), and a methane emission estimate for dairy cattle from Veenendaal et al (2007).…”