Adubação de sistemas: eficiência da aplicação antecipada de nitrogênio na palhada de plantas de cobertura para a produtividade do milho

Abstract

Nitrogen fertilization plays a fundamental role in maize (Zea mays L.) productivity, being the most demanded nutrient by the crop. The anticipation of nitrogen fertilization on the straw of a cover crop mix has been identified as an efficient strategy to improve nitrogen availability throughout the production cycle. This study evaluated the effects of early nitrogen fertilization, using urea, on the straw of black oat, hairy vetch, and forage radish, compared to conventional topdressing application. The experiment was conducted at the experimental station of the Instituto de Desenvolvimento Rural do Paraná (IDR-PR), Pato Branco, in a clayey-textured Rhodic Hapludox. The experimental design was a 2×4 factorial randomized complete block, with two factors: early nitrogen application (150 kg ha of N) or absence, and increasing nitrogen topdressing rates (0, 50, 100, and 150 kg ha). The evaluated variables included maize grain yield, thousand-grain weight (TGW), number of rows per ear, and number of grains per row. Early nitrogen fertilization resulted in a maximum yield of 6,837 kg ha and higher TGW (437 g), regardless of the nitrogen topdressing rates. In treatments without early nitrogen application, grain yield responded linearly to increasing N doses; however, even at the highest rate (150kg ha), the values remained lower than those observed in the early fertilization treatment. The number of rows per ear and grains per row were not influenced by treatments, reinforcing their genetic determination. The results indicate that early nitrogen fertilization is an agronomically efficient and sustainable strategy, promoting higher productivity, better nitrogen use efficiency, and reducing the need for high topdressing rates. Thus, this practice proves to be a viable approach to maximize fertilizer efficiency, reduce costs, and contribute to the sustainability of no-till farming systems.