Recovery of Residual Nitrogen (15N) from Urea in the First Ratoon of Irrigated Sugarcane

Abstract

Despite many losses, nitrogen may remain in the soil for more than one cycle. It can benefit the culture of sugarcane due to its longevity. The objectives of this study were to evaluate the yield of stalks and the recovery of residual N from urea applied to sugarcane (plant-cane cycle), which could be used by sugarcane ratoon subjected to different levels of water replacement and residual nitrogen doses. The experiment was conducted at an experimental area belonging to the Federal Institute Goiano, campus Rio Verde, Brazil, using plastic pots containing dystrophic Red Latosol from Cerrado and cattle manure. The experimental design was completely randomized with three replications analyzed in 3 × 3 split plots. The treatments consisted of three levels of water replacement (75, 50 and 25% of field capacity) and three residual N doses (60, 120 and 180 kg ha−1) in the form of urea enriched with 15N applied to plant-cane in a preceding cycle. Residual N doses influenced the stalk yield. The highest stalk yields was achieved by high water replacements. The nitrogen recovery was high in the residual N dose of 60 kg ha−1 initially applied to plant-cane when associated with water replacement at 75%. Regardless of the N dose applied, the use of residual N was less than 7.06% of the amount originally applied to plant-cane.