Multisite response of sugarcane to nitrogen rates and split application under Brazilian field conditions

Abstract

AbstractBrazil is the world's largest sugarcane (Saccharum spp.) producer, with 8.5 million ha and 643 million t of stalks produced annually. Sugarcane production has a significant impact in the Brazilian economy due to the large production of sugar, ethanol, and energy. The low N use efficiency is a challenge for sugarcane production and may be due to a lack of synchrony between fertilizer application and maximum N demand. This study tested the hypothesis that split N application can improve sugarcane yield by matching fertilizer application and crop demand. We conducted 25 green sugarcane field trials in south‐central Brazil (15 in the first ratoon stage [Year 1] and 10 in the second ratoon stage [Year 2]) divided into three harvest periods: autumn, winter, and spring. We adopted a factorial design at the autumn and winter sites, evaluating N rates and methods of application (total or split), and a complete block design in spring, evaluating N rates. Measurements included stalk yield, total recoverable sugars, and sugar yield. Nitrogen responsiveness was higher in sugarcane harvested in autumn compared with winter or spring. Split N application (i.e., applying half of the N soon after harvest and half at the beginning of the rainy season) showed the potential to increase yields by 3–7 Mg ha−1 in autumn but not in winter. Among the seven responsive sites, the yield gain was 9–10.5 Mg ha−1, and the average yield at 0.8 kg N Mg−1 was statistically similar to those at 1.0, 1.2, and 1.4 kg N Mg−1.