Impacto da adubação durante a vedação de pastagem

Abstract

The objective of this study was to assess the impact of fertilization on enclosed pasture, aiming for increased forage production for use during the dry season. The experiment was conducted at the Federal University of Northern Tocantins (UFNT), on the Araguaína-TO campus, at the Center for Agricultural Sciences (CCA) in the Nucleus of Studies on Ruminant Production in the Legal Amazon (NEPRAL). The experiment began on April 10, 2023, and concluded on October 10, 2023, totaling 180 experimental days. It was subdivided into 90 days of enclosure, from the beginning of the period until July 10, and 180 days of enclosure, from the beginning of the period until October 10. The experimental design used was a randomized complete block design (RCBD) with three fertilization levels, each with four replications. The planned fertilizations according to the treatments totaled 30, 60, and 90 kg ha⁻¹ of N and K₂O for low, medium, and high levels, all with 40 kg ha⁻¹ of P₂O₅, and were applied in the early days of the experiment. Evaluations were performed at the end of each period, with samples collected at 15 cm above the ground, considering the grazing horizon of the animals. The variables studied included total dry matter forage mass (MST - kg ha⁻¹), dry matter of leaf blade (MSLF - kg ha⁻¹), dry matter of stem (MSC - kg ha⁻¹), and from these variables, forage accumulation rate and leaf/stem ratio (F/C) were calculated. In the 90-day period, the MST of the high and low treatments did not differ, with an average of (3.57 ton MS ha⁻²), producing more than the medium treatment. This result was reflected in the forage accumulation rate (TAcF) due to total productions. The other variables did not differ from each other. In the 180-day enclosure period, no variable differed statistically, showing that higher fertilization did not increase dry matter forage. Therefore, the application of 30 kg of N ha⁻¹ would be recommended for good forage accumulation during the dry season, under similar edaphoclimatic conditions to those in the experiment.