Wheat and field beans grown on Gault Clay or a soil-forming material amended with paper-mill sludge

Re-establishment of vegetation on landfill sites, as required by UK planning consents, frequently means establishing viable arable agriculture rather than grassland. However, there is currently little information on crop suitability or yield, especially where the land has been restored with clay subsoils. Results are presented from two years growing field beans and wheat on a landfill site just outside Brighton, England, which has been restored with Gault Clay. The site was restored in two ways. One area had a 1 m depth of Gault Clay applied to the top of the engineered landfill cap. The other area had 300 mm of Gault Clay overlain by 700 mm of potentially topsoil-forming material, formed mainly of screened building waste materials which looked suitable for use as a soil-forming material. The amendments tested were mineral fertiliser and paper-mill sludge. The results show that nothing grew well on the Gault Clay, even when amended. Furthermore, growth was better on the soil-forming material, but yields were still unsatisfactory even when fertilised with mineral fertiliser. The paper-mill sludge produced little improvement in growth and actually suppressed growth significantly on the Gault Clay, and the combination must therefore be questioned as a solution to restoration of capped landfill, 'brownfield' or contaminated land situations.