Effects of municipal sewage sludge on the concentration of macronutrients in soil and plant and some agronomic traits of wheat

Application of sewage sludge as a cheap and waste material is increasing for supporting plant essential elements especially in the soils of arid and semiarid regions. In the present greenhouse research, the effect of Ardabil municipal sewage sludge on N, P, K, Pb, Cr, Ni and Cd concentrations in soil and plant and also spring wheat yield and growth indices was studied as a randomized complete block design with 5 treatments and 4 replications. Treatments were: zero (control), 30, 60, 120 and 180 tons of sludge/ha. The results showed that all rates of sludge application (30 to 180 tons/ha) significantly increased organic carbon (21.94 to 176 percent), total nitrogen (81 to 310.34 percent), extractable phosphorus (16.7 to 123 percent) and extractable potassium (5.34 to 117.8 percent) in the soil under growth of wheat. The concentration of nitrogen, phosphorus and potassium in grain increased significantly in 180 tons/ha treatment about 36.04, 112.34 and 86.64 percent compared with control, respectively. Sewage application increased grain yield and wheat growth indices such as shoot dry weight, height, and grain weight and leaf area. The effect of sludge application rates on the concentration of Pb, Cr, Ni and Cd was not significant in soil. Generally, with consideration the high electrical conductivity of used sludge, the 120 tons/ha treatment can be recommended as suitable application rate for improving chemical quality of soil.