Influence of Phosphorus forms on Growth and Yield of Cowpea, Kales and Amaranth Vegetable Species

Maximum production potential of leafy vegetable is limited by phosphorous (P) deficiency in the soils. This is due to the high cost of the phosphate fertilizer and the fixed form of the available phosphorous in the soil. There is therefore, need for farmers to use alternative and cheaper sources of P that are economic friendly to supply the required mineral nutrition to their crops. Rock phosphate is widely available but has a challenge in solubilization to make P available to the crops. In the current study, the aim was to evaluate the effect phosphate forms and acidulate rock phosphate on growth and yield of selected leafy vegetables. The experiment was laid out in Randomized Complete Block Design in split-plot arrangement, with three leafy vegetables (cowpeas, kales and amaranth) being the main plots, and various sources of P (Triple super phosphate (TSP) Mijingu Phosphate Rock(MPR), Mijingu phosphate Rock + sulphur (MPR)PR+S and control) constituting the subplots with three replicates. The collected data included: root dry weight, leaf area, shoot fresh weight and leaf area and was subjected to SAS for ANOVA and where there were significant differences between means were further separated using the Fischer’s LSD at 5% level of significance. The results revealed that there were significant increase in the growth parameters of the vegetables as an effects of phosphorus application compared with the control. TSP elicited the best results in all the tested parameters in 5 WAP, 6 WAP and 7 WAP respectively in both seasons The highest value of root dry weight (11.2 g), leaf area (1905.0 cm2), number of branches (40.67) shoot fresh weight (236.8 g) as influenced by TSP application in the vegetable species. The MRP + sulphur also followed in superiority of increasing the growth parameters which is an indication that sulphur can be used in solubilizing rock phosphate and making it a suit alternative for farmers. Thus, farmers are advised to directly apply rock phosphate and sulphur to soil as a possible alternative to the more expensive soluble phosphate fertilizers in tropical cropping system.