Possibilities of Using Sewage Sludge as Nitrogen Fertilizer for Maize

Abstract

The objective of this study was to determine the effects of nitrogen fertilizer sources of ammonium sulphate and municipal sewage sludge on yield, N content and uptake of the maize (Zea mays L.). Nutrient and heavy metals were determined in soil and plant. The experiment with three sludge rates ( 256, 513 and 1026 kg total N ha(-1) or 9.5, 18.0 and 38.1 t ha(-1) sludge), two nitrogen rates ( 80 and 160 kg N ha(-1)) and zero-N control were conducted on a clay loam soils under irrigated conditions in Eastern Anatolia region in Turkey. Treatments were arranged in a randomized complete block design with four replications. Yield, N content and total N uptake of maize increased significantly with sludge application. 9.5 t and 19.0 t ha(-1) sewage sludge applications did not significantly affect heavy metal content of leaf and grain. However, 38.1 t ha(-1) sludge applications increased leaf Pb and Zn. DTPA-extractable Cd, Cu, Fe, Pb and Zn concentrations of the soil increased at applications of 38.1 t ha(-1) sewage sludge, whereas applications of 9.5 t and 19.0 t ha(-1) sludge only resulted in elevated levels of Cu and Zn. We conclude that if sewage sludge is to be used in production of maize, applications rate up to 19 t ha(-1) could be accepted. However, this means also that the N requirement of maize crop is not covered by the sludge; therefore, the rest of nitrogen could be supplied as inorganic N.