Accumulation of macronutrients in jambu plants as a function of organic fertilizer application

Jambu is a vegetable native to the Amazon region. Among its management practices, organic fertilization is used to increase the crop’s productive potential. This study aimed to evaluate the effect of the application method of organic fertilizers castor bean cake (CBC) and hoof and horn powder (HHP) on the accumulation of macronutrients in jambu. Experiments were conducted in two production areas: Botucatu-SP and São Manuel-SP. Eight treatments were evaluated in a 2 x 4 factorial scheme, comprising two organic fertilizers (CBC and HHP) and 3 forms of application (100% before planting; 100% as topdressing; and 50% before planting + 50% as topdressing), plus a control without fertilizer. The dry mass of inflorescences (DMI), dry mass of vegetative parts (DMV), and total dry mass (DMT) were evaluated in both areas, while macronutrient accumulation was assessed only in Botucatu. Compared to the control, topdressing treatments resulted in increases of 129%, 134%, and 134% in São Manuel, and 284%, 70%, and 85% in Botucatu, for DMI, DMV, and DMT, respectively. The three most abundant nutrients in jambu plant tissues were potassium, nitrogen, and calcium.