Landfill leachate nutrient recovery by willow short rotation coppice II. Soil quality

摘要

The application of landfill leachate to willow short rotation coppice (SRC) has been shown to enhance the growth of the crop and has lead to substantial offtakes of constituent chemical components (GODLEY et al., 2004). Despite the attenuation of leachate by crop growth there is potential for soil contamination in particular from sodium (Na) and chloride (Cl) constituents. A study of the soil chemical conditions at the Hatfield trial site (GODLEY et al., 2004) demonstrated that while there were significant increases in soil Cl and Na concentrations following leachate application, the effects were short lived and winter leaching from the soil returned levels similar to those of the control plots after 7 months without leachate irrigation. The Hatfield willow SRC trial showed that there were no significant effects (P > 0.05) from leachate application on the soil concentrations of total calcium, total magnesium, total phosphorus, cadmium, chromium, copper, mercury, nickel, lead and zinc. Additions of these components were negligible compared to the mass already present in the soil, therefore it was unlikely that leachate application would have significantly changed their soil concentration. Ammonium-nitrogen (NH4-N) was similarly unaffected by leachate applications, however elevated soil nitrate-N (NO3-N) contents in leachate treated soil indicated that nitrification processes convert a proportion of the NH4-N applied to NO3-N. Leachate irrigation raised the plant available K, Mg and B contents of the soil by a small amount but levels remained within the ranges of crop nutrient status.