Use of By-Products Reduces Nitrogen Fertilizer Requirements for Sugarcane Production in Brazil.

Sugarcane is an important crop for food and energy production in Brazil. The main by-products generated in the process of sugar and ethanol production are filter cake and vinasse, which contain nutrients and are usually applied in sugarcane fields. In areas with historical usage of these amendments, there has been observed a decrease in N fertilizer requirement for sugarcane production. This study hypothesized that continuous application of vinasse in sugarcane fields will decrease N fertilizer requirement. Two field trials were set up in São Paulo State, Brazil, in areas with (site 1) or without (site 2) previous usage of vinasse. A randomized complete block experimental design was adopted in each trial, including five treatments (check-plot, 50, 100, 150, 200 kg ha-1 N) and five replications. Fertilizers were applied manually on soil surface, and yield was measured after a 12-m crop cycle period. As expected, nitrogen fertilization increased sugarcane stalk yield in site 2, whereas no effect of N fertilizer occurred in site 1. The results indicate a potential reduction in nitrogen fertilizer application in fields with historical use of nutrient containing by-products.