Field experiments were conducted during 2016 and 2017 cropping seasons in the derived agro-ecological zone of Nigeria to study the combined and sole effect of zinc and boron fertilizers on the growth, seed yield, and quality of groundnut (Arachis hypogaea L).e experiment was laid out in randomized complete block design (RCBD), replicated four times. ree levels of zinc (0, 4, and 8 kg·ha − 1 ) and four levels of boron (0, 300, 600, and 900 ml·ha − 1 ) were combined and evaluated. Groundnut seeds were analyzed at the end of the experiments to determine nutrient elements and some heavy metal contents. Data collected were subjected to Statistical Analysis of Variance using SAS 2000. Treatment means were compared using the Duncan multiple range test at 0.05 level of probability. e effect of zinc was not significant on the vegetative parameters, while application 8 kg Zn·ha − 1 significantly increased number of seeds, weight of seeds, seed yield per hectare, and seed quality though the values were similar to the application of 4 kg Zn·ha − 1 only on the seed yield and its parameters. Application of 600 and 900 ml B·ha − 1 gave higher and statistically similar values for vegetative parameters, yield, and yield parameters, while 600 ml B·ha − 1 significantly improved the seed quality. It can therefore be recommended that for optimum yield and seed quality, application of 8 kg Zn·ha − 1 combined 600 ml B·ha − 1 is sufficient in the study area without increasing the heavy metal concentration of groundnut seed.Means in a column under any given treatment followed by the same letters do not differ significantly at 0.05 level of probability using the Duncan multiple range test (DMRT). * Significant at 0.05 level of probability.

AbstractNutrients 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.

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Background: The optimum rate of nutrient must be defined with reference to soil properties for individual crops and soil. Objective: Field experiments were carried out in 2015 and 2016 cropping seasons to determine the various levels (0, 40, 80, 120 and 160 kg ha-1) of potassium fertilizer (muriate of potash , KCl), on soil chemical properties, leaf nutrient contents, performance and proximate quality of sweet potatoes (Ipomoea batatas L.). Method: The five treatments were arranged in a randomized complete block design with three replicates. Results: Studies showed that K fertilizer in both the years significantly influenced N, P and K concentrations compared with the control and also increased the soil concentrations of these nutrients from 0 - 160 kg ha-1 K fertilizer. However, soil K only increased up to 80 kg ha-1 fertilizer after which there was a decrease. There was a reduction in the values of Ca and Mg in the soil as the levels of K increased. Leaf nutrient concentration of the sweet potato was consistent with the values of soil chemical properties recorded. 80 kg ha-1 K fertilizer was observed to be the highest value of sweet potato growth and tuber yield after which there was a reduction. The yield decrease was adduced to excessive K application leading to imbalanced sweet potato plant nutrition compared with N, P, Ca and Mg. K fertilizer significantly influenced moisture, vitamin C and carbohydrate compared with the control. The highest values of fibre and protein were obtained at 80 and 40 kg ha-1 K fertilizer, respectively. Dry matter and fat contents of the sweet potato reduced by K application from 0 - 160 kg ha-1 application rate. Conclusion: For best tuber yield, quality and economic response of K fertilizer to the sweet potato in the agro-ecological zone or in other similar soil conditions elsewhere in the tropics could be achieved by applying 80 kg ha-1 K fertilizer.

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Background: Soil health is an important factor for producing a higher yield and obtaining good quality products. Nitrogen fertilizer is one of the most important and valuable agricultural inputs for increasing crop production. Objective: Experiments were conducted in 2017 and 2018 in the cropping seasons to determine the performance and nutritional qualities of sweet pepper in response to organic and inorganic sources of N fertilizers. Methods: Ten kilograms (10 kg) capacity black polythene bags were filled with topsoil and were arranged randomly on the field. Treatment combination included: - 0 NPK + 0 PM (T1), 40 NPK + 0 PM (T2), 32 NPK + 8 PM (T3), 24 NPK + 16 PM (T4), 0 NPK + 40 PM (T5), 8 NPK + 32 PM (T6), 16 NPK + 24 PM (T7) and 20 NPK + 20 PM (T8). Experiments were laid out in a completely randomized design and were replicated four times. Vegetative, flowering, and quality parameters were collected and analyzed using the GenStat Discovery, 2014 statistical analysis software. Separation of means was determined by the Duncan Multiple Range Test (DMRT) at a probability level of 5%. Results: Results indicated that high rates of an organic source of N fertilizer produced higher values for vegetative and yield parameters, which was similar to the sole application of inorganic fertilizer. There was no significant effect of the sole application and combined organic and inorganic sources of N fertilizer on heavy metals and nitrates accumulation, but their effects were able to increase the values for nitrites above the recommended limits as suggested by the Joint FAO/WHO Expert Committee on Food Additives. Conclusion: Our results showed that 20 NPK + 20 PM is the best treatment without any health implications in the study area, which also improved the yield and, therefore, can be considered economical.