Effects of sewage sludge application on contents of heavy metals in the soil and growth of maize

Through pot experiments, the effects of various sludge loadirigs(0, 40, 80, 120, 200, 280 t.ha(-1)) on growth of maize and sewage sludge application on contents of heavy metals in the soil were studied using sewage sludge from An-fling Plant of Wastewater Treatment of Lanzhou City. The results showed land application of sewage sludge increased significantly the contents of Pb, Cu, Zn in the soil. The contents of Pb, Cu, Zn in the soil did not exceed the standard of Environmental quality standards for soils for Grade II (GB-1518-1995) in china. Maize obtained good growth activities after land application of sewage sludge, maize height and biomass were increased significantly and were better than the control. Land application of sewage sludge inhibited maize seedling emergence and maize root length, showing the effects of dose-effect relationship with sludge application increasing. Maize root length was restrained significantly by heavy metals in the soil, the effects of heavy. metals in the soil on plant root system should be considered with land application of sewage sludge. The optimal land application of sewage sludge is 80-120 t.ha(-1).