INFLUÊNCIA DE DOSES DE FOSFATO DE ROCHA NA DISPONIBILIDADE DE NUTRIENTES EM DIFERENTES CLASSES DE SOLOS DO TOCANTINS

Abstract

Phosphate fertilization is essential for agricultural crops on Cerrado soils, and identifying alternative sources
of phosphorus is critical to reduce dependency on the international market and ensure the sustainability of
Brazilian agribusiness. This study aimed to evaluate the availability of plant nutrients in response to different
rates of rock phosphate incubated in four soil types from Tocantins. The incubation test was conducted in the
laboratory using a completely randomized design with four replications. Treatments followed a 4x5 factorial
scheme, combining four soil types (Neossolo Quartzarenico, Latossolo Vermelho, Latossolo VermelhoAmarelo, and Gleissolo) and five rates of rock phosphate (0, 2, 4, 6, and 8 t/ha). Rock phosphate application increased soil pH only in Latossolo Vermelho, from 5.43 to 5.49 at 8 t/ha. Phosphorus availability, measured using the Mehlich 1 extractant, peaked at 8 t/ha in Neossolo Quartzarenico (78.47 mg dm-³), Gleissolo (67.69 mg dm-³), Latossolo Vermelho-Amarelo (31.73 mg dm-³), and Latossolo Vermelho (35.96 mg dm-³). Using the ion exchange resin extractant, P content at 8 t ha-1 reached 49.12 mg dm-³, 31.12 mg dm-³, 16.35 mg dm-³, and 14.64 mg dm- ³, respectively. Calcium content significantly increased in Neossolo Quartzarenico, Latossolo Vermelho, and Latossolo Vermelho-Amarelo, reaching 3.29, 2.40, and 2.06 cmolc dm-³, respectively, at 8 t ha-1. Magnesium and potassium contents were not significantly affected, nor were potential acidity (H+Al) and base saturation (V%). These findings indicate that rock phosphate application improves phosphorus and calcium availability in certain soil types without impacting other essential soil attributes.