摘要
A field experiment with cotton was conducted on a well drained, calcareous, clay loamy Typic Xerochreptto investigate the utility of sewage sludge as a partial substitute for fertilizers and the influence of its application on the basic soil properties and heavy metal concentrations. The experimental design was completelyrandomized blocks with five treatments replicated four times each. Sewage sludge came from the treatmentplant of the municipality of Volos, Central Greece, with the following characteristics: organic matter content36.6 %, pH (H2O 1:5) 6.89, CaCO3 53.4 g kg-1 , total N 26.5 g kg--1, total P 33.5 g kg--1 , and total K 968mg kg--1 soil. Heavy metal concentrations were Cd 5.24, Pb 442, Ni 38, Cu 224, Zn 1 812, and Mn 260 mgkg--1 dry weight, respectively. The soil was high in potassium (K) and poor in available phosphorus (P). Theresults showed that sewage sludge application increased cotton yield and K and P concentrations in cottonleaves. Soil pH was reduced in the case of higher sewage sludge rate. Electrical conductivity, organic mattercontent, total N, and available P were significantly increased. Total concentrations of Zn, Pb, and Cu wereslightly increased. DTPA-extractable Zn, Cu and Mn were also significantly increased. Available forms ofall heavy metals, except Cd, were significantly correlated with organic matter content in a positive way andnegatively with soil pH.
INTRODUCTIONTheneedoftreatingsewageeffiuentstomaintainhighqualitydischargesintoreceivingwatersleadstotheproductionofappreciableamountsofsewagesludgewhichmustbedisposedinaneconomicandsafeway.Sewagesludgecontainshighamountsofelementslikenitrogen(N),pho...
