“Critical levels and sufficiency ranges for leaf nutrient diagnosis in cowpea grown in the Northeast region of Brazil”, Rev. Ciênc. Agron., vol. 51, nº 4, p. 1–9, set. 2020, Acesso em: 25º de abril de 2026. [Online]. Disponível em: https://periodicos.ufc.br/revistacienciaagronomica/article/view/88831