the effects of rose water distillation residues on mechanical strength and water holding capacity of soil and the growth of barley

rose water residues are by-products of rose water industries. these residues do not have any industrial usage and they are returned to soil as crop fertilizer. in this research, the effects of adding rose water distillation residues to soil in different particle sizes and weight proportion were investigated and changes in mechanical strength, and water holding capacity of soil and the growth of barley were determined. the experiments were performed using a 3 × 3 factorial design in which the weight proportions of the residues were in three levels of 4%, 8% and 12%. the second factor was the size of the residues in three sieves meshes of 6, 16 and 20. the results indicated that with increase in the weight level of residue more moisture was retained by the soil, and the size of the soil particles had lower effect on water holding capacity of the soils. the mechanical strength of the soil decreased with increase in both weight proportion and the particle size of the residues. the length of the stems and roots did not show any definite trend with the variations in factors. in this research, the change in moisture content of the soil was expressed as a linear function of time and residues weight proportionas well as the particle size. the resulting model was well fitted to the experimental data (r2>0.98).