Effects of various agro-industrial residues on soil fertility and yield and quality of potatoes.

Nine combinations of production residues of agro-industries, urban wastes and mineral fertilizers were applied to potatoes (Solanum tuberosum var. Marabel) in a field experiment, and the effect of these combinations on soil characteristics, on yield and on various quality parameters of tubers were determined. The applications significantly affected soil pH, CaCO3 and organic matter content. Total N and available P and K levels of soils showed significant differences between the applications. The content of available Zn and Mn in the soil differed significantly between the applications. Sufficient levels of N, P and K were not attained in leaves in any application. Significant differences were observed between the P content of the leaves of the control and of the other applications. Potassium and Na content of the leaves showed significant variations between the applications. Manganese was at a statistically higher level in the leaves of some combinations. The nitrogen, P and Mn contents of tubers differed significantly between the applications. Phosphorus, K, Mg and Cu levels were found to be sufficient, but Fe, Zn and Mn were low in tubers. Tuber yield was statistically highest in the Wastes P + Mineral NK combination. Reduced sugar and protein content of the tubers was affected significantly by the applications. Significant correlations were found between soil, leaf and tubers.