Dry Bean Response to Fertilization Using Minjingu Phosphate Rock and Composted Tughutu (Vernonia subligera O. Hoffn)

Abstract

Aims: The objectives of the study were toevaluate the effects of organic materials from Tughutu (Vernonia subligera O. Hoffn) and locally available Minjingu phosphate rock or commercial Triple super phosphate fertilizer on the plant growth and amount of phosphorus (P) and calcium (Ca) content in bean shoots (Phaseolus vulgaris L.) and their residual effects in the soil after harvest. Study Design: The experiments were set up as a randomized complete block design Place and Duration of Study: Field experiments were conducted in famers’ fields in the Western Usambara Mountains in Tanzania. Methodology: Each farmer’s field was assigned as a replicate. The experimental treatments consisted of six plots as follows: control, Minjingu Phosphate Rock (MPR) or Triple Super Phosphate (TSP) each at 26 kg P ha-1, Tughutu at 2.5 t dry matter ha-1 and Tughutu at 2.5 t dry matter ha-1 combined with Minjingu Phosphate Rock or Triple Super Phosphate at 26 kg P ha-1. Results: The dry matter yield and amount of P and Ca in bean shoots significantly increased by supplying the organic and inorganic fertilizers above the control treatment. Addition of P fertilizers alone or in combination with Tughutu also modified the soil pH and significantly increased the concentration of P and Ca in the soil at harvest. Conclusion: Overall, combination of Minjingu phosphate rock or Triple super phosphate with Tughutu enhanced the effectiveness of these fertilizers and resultedin better growth and greater P and Ca amount in the shoots as well as their concentration in the soil at harvest.