A field experiment has been carried out in one of Yousifia village fields – Baghdad Province to investigate the effect of dried sewage on some chemical proprites in calcarious clay loam textured soil and their effect on the growth and yield of Lettuce plant uses randamized complete block design (RCBD) of triplicates. The experiment includes two treatments : the first one using mineral fertilizers and the second treatment uese mineral fertilizers with 40 ton.ha-1 of dried sewage sludge , mixed with soil to a depth of 30 cm. Mineral fertilizers are applied to all treatments in an average of 180, 220 and 80 kg.ha-1 of Urea (46% N) , super phosphate (20% P) and Potassium sulphate (41.7% K) respectively. Lettuce is planted at 2/11/2012 and irrigated with a river water after consumption of 75% of available water. In 18/2/2013 the plants have been harvested randomly from each replicate , fresh and dry weight measured . Soil and leaves samples from all treatments are taken for analysis.
Results showed: a Significant increase in each of these chemical properties : Electrical conductivity ( from 3.80 to 4.16 dS.m-1),cation exchange capacity (24.28 – 25.36 Cmol+kg-1),soil content of organic matter (8.70 – 11.89 concentrations of soluble ions , available nitrogen ( 0.42 – 0.81 ) , available phpsphorus ( 8.6 – 19.81 , yield and notsigniricant increase in sodium adsorption ratio values (2.54 – 2.80 (mmol/L)½) , while there is a significant decrease in soil reaction values (7.74 – 7.61 ) and decrease in concentrations of available potassium
The results confirm the possibility of using sewage sludge as a good organic fertilizer in Iraqi calcareous soils .