CaHPO4 center dot 2H(2)O and NH4H2PO4 were used for fertilizing the CaCO3 and/or red clover straw-contg. lessive, medium heavy and fertile soils (P doses 100-200 mg/kg) used for growing maize and buckwheat in pot expts. The fertilization resulted in an increase in plant biomass yield and in P uptake by the plants. The presence of lime and straw resulted in increasing the biomass yield and P uptake. The methods used for detn. of P content (Yanai, Egner-Riehm P active and P desorption after Huay) gave quite different results.