Physical properties of low-lying agricultural peat soils in England

The drainage of low-lying peatland for agriculture and subsequent conservation measures adopted on some of these peatlands has led to differing degrees of change in the physical and hydraulic characteristics of the soil. We assessed the degree of peat decomposition and measured the soil organic matter (SOM) content, particle density, dry bulk density, saturated hydraulic conductivity, and water retention and shrinkage characteristics for a range of peat soil horizons sampled in two low-lying agricultural peatland in England. The physical and hydraulic properties of the peats considered were significantly influenced by the degree of decomposition. Higher decomposition resulted in lower SOM content, higher bulk density and lower porosity. In addition, pedogenic alterations due to intensive drainage and land use lead to a greater degradation of the soil structure in the upper soil layers. Less decomposed peats had a higher propensity to shrink under increasing water potentials. They had a lower air entry pressure and drained faster than degraded peats. In addition, they had a higher saturated hydraulic conductivity. This shows that decomposition and pedogenic alterations lead to the loss of structural pores. Hence decomposition and humification result in the degradation of the soil structure and a reduction in the soil capacity to store, retain and transmit water.