Effects of phosphorus and zinc fertilizers on their contents in soil, plant and grains of corn

Experiments were conducted for two seasons 2000/01 and 2001/02 to study the effects of phosphorus and zinc fertilizers and their interactions on their soil extractable forms, their contents in corn (Zea mays L.) leaf tissue, and their grain uptake. The study was conducted on Remaitab soil series (fine, smectitic, isohyperthermic, typic Haplusterts) at the Gezira Research Station Farm, Agricultural Research Corporation, Wad Medani, Sudan. Phosphorus was applied as triple superphosphate at three rates (0, 43 and 86 kg P2O5 ha-1). Zinc was added to the soil as zinc sulphate (Zn SO4.7H2O) at three rates (0, 5 and 10 kg Zn ha-1).  The experiments were arranged in a split-plot design with four replicates. The main plots were assigned to phosphorus rates and .the sub plots were assigned to those of zinc. The treatments were completely randomized within each replicate. The results indicated that application of both nutrients significantly (P < 0.05) increased most of the parameters studied. Extractable soil Zn measured at 14 and at 70 days after sowing (DAS) and available soil P measured at 70 DAS were significantly reduced by the interaction of soil application of phosphorus and zinc fertilizers and both nutrients tended to reduce the concentration of each other in leaves especially when one of them was not added, and this was more pronounced in the cases of added P treatments on leaf tissue content of Zn. The results indicated that the major P-Zn interaction did not take place in the plant but in the soil where the availability of Zn was reduced by P and this was readily corrected by application of Zn. Application of both phosphorus rates in combination with zinc improved grain uptake of both nutrients, compare-ed to treatments receiving the same amounts of phosphorus but without zinc or treatments receiving no phosphorus with or without zinc applic-ation