Synergistic and antagonistic effects of soil applied P and Zn fertilizers on the performance, minerals and heavy metal composition of groundnut

Nutrients use efficiency of plants could be affected by the antagonistic or synergistic effects of two or more elements in the soil leading to decreased or increased yield. Field experiments were conducted in 2017 and 2018 cropping seasons at the Landmark University Teaching and Research farm, Omu-Aran, Nigeria, to determine the interaction between zinc (Zn) and phosphate (P) fertilizers on growth, yield, nutrient elements and some heavy metals composition of groundnut grown on an Alfisol. Treatments consisted of four levels of phosphorus (0, 40, 80 and 120 kg P ha-1) and three levels of zinc (0, 4 and 8 kg Zn ha-1). The experiment was laid out in a Randomized Complete Block Design (RCBD), replicated four times. The following parameters were taken: plant height, plant spread, total biomass, number of pods/plot, weight of pods/plot, number of seeds/plot, weight of seeds/plot. Laboratory analysis of some chemical constituents of groundnut seed was carried out to determine the nutrient and heavy metals composition. Results indicated that application of 8 kg Zn ha-1 and 120 kg P ha-1 had a synergistic effect on the growth parameters and antagonistic effect on the yield, yield parameters, some nutrient elements and beneficial heavy metals. Application of 8 kg Zn and 80 kg P ha-1 is therefore recommended on an Alfisol without necessarily increasing the concentration of non-beneficial heavy metals in groundnut seed