Agronomic performance of sugarcane cultivated under quantities of sugarcane straw on the soil surface

Abstract

Mechanized harvesting is increasingly present in the sugarcane production system. The straw removed during harvest can be converted to ethanol or used to generate electricity by burning, it is important to determine the amount of biomass that may be removed without damage to the crop. We evaluated the agronomic performance of sugarcane, variety RB92579, grown under different quantities of sugarcane straw on the soil surface, in the first and second year of cane crop. We used the experimental randomized block in split plot design, with four replications. In the first year the plots received five quantities of straw (0, 4.5, 9.0, 13.5 and 18 Mg ha^-1), and six times assessments (60, 120, 180, 240, 300, 360 days after planting) arranged in the subplots. In the second year, the plots received the same quantities of straw and four times assessments (60, 120, 240 and 540 days after the regrowth) in subplots. Biometric indexes, components of production and crop yield were evaluated. The data were submitted to variance analysis and study of polynomial regression (p <0.05). Increasing quantities of sugarcane straw deposited on the soil surface reduces the number and diameter of the stem at the beginning crop establishment, and number of sheets for the first year. The maximum productivity of stems is achieved by maintaining 9,6 Mg ha^-1 of straw for first year and 4,7 Mg ha^-1 of straw for second year of cane crop.