The effect of two phosphatic fertilizers on growth, yield components and yield of maize (Zea mays)

This study was carried out during season 1999-2000, at the Agricultural Research Corporation (ARC) farm, at Wad Medani, to investigate the effect of Nitrophoska (NPKa 18:18:5) fertilizer, on growth, yield components and yield of maize (Zea nats). Nitrophoska has been introduced very recently in Sudan, as a nitrogenous fertilizer, under experimentation, in an attempt to promote crop yield. Because NPKa contains an appreciable amount of P ( 18P2 O5), it was tested here as a phosphatic fertilizer against the ever used triple superphosphate (TSP 46P2 O5). Each fertilizer (NPKa and TSP) was applied to the soil at a rate of OP, 1P 1.5P, and 2P (1P=43 kg P2O5ha-1). N was applied in urea form as a basic nutrient at a fixed rate of 2N (2N= 86 kg Nha-1). The N content of the NPKa treatment were calculated and adjusted to 2N by urea application. Urea was applied by broadcasting, on soil surface before sowing, while NPKa and TSP were applied by banding also before sowing. The results of this study showed that NPKa fertilizer was superior to TSP fertilizer in growth, yield components and yield, particularly at higher doses. Also the results showed that NPKa source led to significantly higher uptake of NPK as compared to TSP source. This might be partially due to the synergistic interactions between P and N, partially due to the two forms of N (NO3 and NH4) and partially due to the secondary and some trace elements that NPKa source contains. Therefore NPKa fertilzer could be used as a dual fertilizer to supply N and P, in addition to the secondary and some trace elements. The laboratory data of some soil samples taken after the termination of the experiment showed that the total nitrogen and the available phosphorus decreased with increasing rate of P application, but their decrease was not beyond the soil before fertilizer application. This was true for both fertilizer (NPKa and TSP), a matter which indicates their residual effect. However, the effect was more pronounced for NPKa source than for TSP source. This means that NPKa has longer residual effect than TSP source. The experiment was not economically evaluated for the difficulty in obtaining the really true price of the maize grain in Sudan