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

Abstract

Abstract Brazil 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 .