Landfill Leachate as Irrigation Water for Tree and Vegetable Crops

The effects of landfill leachate (from Gin Drinker's Bay landfill, Hong Kong) on the growth of tree and vegetable crops were studied in a greenhouse. Higher yields were obtained for Brassica chinensis (Chinese White Cabbage) and B. parachinensis (Flowering Chinese Cabbage) with 5, 10, 20 and 40% leachate dilutions than in the non-leachate control. Yield was reduced for Acacia confusa (Acacia) under all concentrations of leachate treatments. Inhibition of root growth was also observed in the three species with 40% leachate treatment. Leachate-treated soil had elevated levels of electrical conductivity, total-, ammonia) and nitrate-N, exchangeable Na and P. For all heavy metals analysed, only Mn significantly ( p < 0.05) accumulated in soil after leachate irrigation. Uptake of N, Na, Fe and Mn was evident for all test species after leachate irrigation. The degree of uptake was positively correlated ( p < 0.05) with the leachate concentrations used for irrigation.