Uso de resíduos de peixe como biofertilizante no cultivo de espinafre-amazônico (Alternanthera sessilis)

Abstract

This study evaluated the effect of using a fertilizer based on fish residues from South American silver croaker (Plagioscion spp.) on the cultivation of Amazonian spinach (Alternanthera sessilis). To this end, the fertilizer was produced through a composting process using filleting residues from this fish species. Subsequently, to evaluate the resulting compost (biofertilizer), spinach samples were cultivated in the following substrates: T1 (= soil + 59 g of fish residue compost) and T2 (= soil + 27.6 g of fish residue compost); and controls T3 (= no fertilizer added to the soil), T4 (= soil + 3 g of NPK), and T5 (= soil + 3 g of chicken litter), all placed in black plastic bags. The cultivation period lasted 60 days, and during this experimental period, plant survival and height were evaluated every two weeks as indicators of the efficiency of the fish residue compost as a fertilizer. The results showed that, after 60 days, the survival rate reached 100% in all substrates except T4 (80%). Although plant height did not differ significantly after 30 days of cultivation, after 60 days, plants fertilized with fish compost exhibited greater growth than those cultivated in the other substrates. Regarding leaf number, the highest values were observed after 60 days in substrate T1, which contained the highest amount of fish residue biofertilizer. Fertilization with fish residue biofertilizer provided sufficient nutrients for adequate plant growth compared with the other substrates tested. Therefore, the use of fish residue compost contributed effectively to the cultivation of Amazonian spinach.