Maize was grown in monoculture throughout the consecutive years 2003-2007 in Nowa Wieś Królewska (52^o26’ N; 17^o57’ E). A two factorial field experiment was established on a slightly acidic soil, moderately rich in available phosphorus. Experimental factors were as follows: 1) chemical formulation of the fertilizer (simple superphosphate – SSP, triple superphosphate – TSP, partially acidulated phosphate rock – PAPR), 2) nitrogen rate: 80 and 140 kg N·ha^-1. A phosphorus unfertilized treatment (control) was also considered. The yield forming effect of TSP and PAPR (at the rate 26.4 kg P·ha^-1) was similar, irrespective of nitrogen fertilization. Mean agronomical efficiencies of phosphorus (AE-P) for TSP amounted to 13.2 and 19.1 kg·kg^-1, respectively for 80 and 140 kg N·ha^-1, whereas in the case of PAPR, 14.4 and 17.8 kg·kg^-1. respectively. In relation to calcium phosphate from superphosphate, the partially acidulated phosphate rock may be considered as an alternative source of phosphorus for maize grown for grain. The influence of sulphur from SSP on maize grain yield was higher after the application of the lowest nitrogen rate. The deficiency of phosphorus in the control treatment has led to a grain yield decrease in the order 9-19% as a result of both the low number of kernels per cob and the weight of 1000 kernels (TKW).

71-79