EFFECT OF MINERAL AND ORGANIC-MINERAL FER TILIZERS ON YIELDS OF CROPSAND ON SOIL FERTILITY FACTORS

The use of adequate amounts of fertilizers is important for soil and c rop management. The objective of this study was to determine the effec t of mineral and organic-mineral fertilizers and of poultry manure on soil fertility factors and on yield of wheat, soybeans, and oats. Mine ral sources of NPK were ammonium sulphate, triple superphosphate and p otassium chloride and organic sources were lignite, peat and poultry m anure. Significant differences were obtained between mineral and organ ic-mineral fertilizers in soil P in five samplings. No differences wer e determined in eight samplings in other soil fertility factors (pH in water, pH in SMP buffer solution, K, organic matter, and exchangeable Al and Ca+Mg). Poultry manure applied to the soil without any previou s treatment promoted similar yields as mineral fertilizers. Average yi elds from plots receiving equal amounts of NPK either through organic or mineral sources, were not statistically different. However, the cos t per unit NPK of the organic-mineral fertilizers was about twice as m uch as that of mineral fertilizers.