Produtividade de milho cultivado em solo de cerrado amapaense submetido a adubação potássica e fosfatada

Abstract

Mineral nutrition, especially phosphorus (P) and potassium (K), is essential for increasing the productivity of crops such as maize. Potassium plays a key role in grain quality, while phosphorus is often a limiting nutrient in Cerrado soils, making phosphate fertilization indispensable. In this context, studies evaluating appropriate doses of these nutrients are necessary to enable and enhance maize production in low-fertility soils. This study aimed to evaluate the productivity of maize cultivated in Cerrado soil from Amapá under potassium and phosphorus fertilization. The experiment was conducted at the experimental farm of the Federal Institute of Education, Science and Technology of Amapá (IFAP), Porto Grande Agricultural Campus. A randomized complete block design was used, arranged in a 4 × 4 factorial scheme with four replications, totaling 64 experimental units. Treatments consisted of four potassium doses (35, 70, 140, and 280 kg ha−1 of K2O) applied as potassium chloride (KCl) and four phosphorus doses (45, 90, 180, and 360 kg ha−1 of P2O5) applied as single superphosphate. The soil of the experimental area was classified as a dystrophic Yellow Latosol, and liming was performed 30 days before sowing. At 76 days after cultivation, plant height, number of grains per ear, 100-grain weight, and total grain weight per plot were evaluated. The results showed a significant interaction between phosphorus and potassium doses. Phosphorus was the most limiting nutrient, requiring high application rates to overcome soil fixation and enable maize production in the Cerrado of Amapá. Phosphorus doses significantly influenced all evaluated agronomic variables, whereas potassium had a significant effect on plant height and grain yield. The highest productivity was achieved with the combined application of 180 kg ha−1 of P2O5 and 280 kg ha−1 of K2O, highlighting the efficiency of integrated nutrient management. Therefore, this combination is recommended to maximize the productive potential of maize in the region.