Dados do Trabalho

Título

NITROGEN FERTILIZER (15N) ON AGRONOMIC PERFORMANCE AND NUTRITION OF CORN IN BRAZILIAN CERRADO OXISOL

Resumo

Abstract  Nitrogen (N) is  the nutrient required in greater quantity and is the highest share cost in the production of corn (Zea mays L) in Brazil. Urea is the most widely used N fertilizer in  the country and in the world, due to its comparative advantages, mainly in terms of final cost to the farmer. The dynamics of N in the soil-plant system and consequent nitrogen use efficiency (NUE) by plant, is mainly influenced by the cultivation system, type of fertilizer, forms of management and soil and climatic conditions. The aim of this study was to evaluate the effect of N rates on corn yield and fertilizer NUE urea-15N. The study was carried out in Selvíria, State of Mato Grosso do Sul, Brazil, in an Oxisol (Rhodic Haplustox), under no-tillage system. The experimental design was in randomized blocks, with four replicates. The treatments were four N rates 30, 60, 120 and 180 kg ha-1, as urea (15N), applied in topdressing, at five leaves stage. The average corn grain yield was 5.50, 6.80, 8.05 and 8.28 t ha-1, respectively, with the application of 30, 60, 120 and 180 kg N ha-1, whose data fit the quadratic regression model: y = 4078.7 + 54.175x – 0.1717x2 (R2 0.997). The N use efficiency by corn was on average of 48% (14.5 kg ha-1); 48% (29.0 kg ha-1); 50% (60.0 kg ha-1); and 35% (63.3 kg ha-1), respectively, with the application of 30, 60, 120 and 180 kg N ha-1. The N rate of 120 kg N ha-1 provided the higher benefit/cost ratio compared to the other N rate. On average, the NUE by corn plant (straw + grains) was 45.5% of the N rate applied. Regardless of N rate, 65% of the absorbed N accumulated in the grains, and 35% in the straw (crop residues). The soil N (native N) was the main source of this nutrient for corn, which highlights the need to emphasize soil management practices and crops that supply N to the soil-plant, for the long term maintenance of its productive potential of the soil.

Palavras-chave

Zea mays L.; Urea; Grain yield; 15N isotope dilution technique.

Instituição financiadora

To FAPESP and CNPq.

Agradecimentos

UNESP - Campus de Ilha Solteira.