Assessing the effects of harvesting with and without burning and vinasse application in sugarcane crops: Evaluation of soil fertility and phosphorus pools in different ethanol production systems

•The application of vinasse reduced the pH and surface availability of nutrients.•The application of vinasse increased the availability of K+ and labile P with depth.•Cultivation without burning with straw deposition did not increase P content.•The maintenance of straw on the soil surface reduces the pH values.•All cultivation systems were efficient in forming the legacy of P in the soil. Ethanol is recognized worldwide as a clean and renewable energy source. In tropical and subtropical countries, it is produced from sugarcane (Saccharum officinarum). In this study, we investigated the effects of sugarcane management systems: a) burning of sugarcane for harvest for 37 years (SCB37); b) burning of sugarcane for 3 years after 5 years of fallow (SCB3); c) sugarcane field without burning for harvest for 3 years (SCWB), and d) burning for harvest with the application of vinasse for 3 years (SCV), on soil fertility and accumulation of organic and inorganic fractions of phosphorus (P) in sugarcane crops for bioenergy production in south-east Brazil. Soil samples were collected at depths of 0–5, 5–10, 10–20, and 20–40 cm between planting rows in each management system and submitted for evaluation of soil fertility and accumulation of P fractions via sequential fractionation. We observed that application of vinasse reduced the pH (3.7–4.2) and the availability of Ca2+, Mg2+, and K+ on the surface, associated with the increase in Al3+ content and potential acidity. However, its use increased the availability of K+ and inorganic P content of higher lability (extracted with NaHCO3) in the subsurface. The maintenance of straw on the surface promoted reductions in pH values and an increase in the potential acidity and was inefficient in the accumulation of organic and inorganic fractions of P, compared to the system with the application of vinasse. Overall, we observed that the moderately labile fraction (organic and inorganic) represented on average 60 % (higher participation) of the total P content of soil in the experimental areas and was more significant in the soil under vinasse application and less evident in the treatments without burning and in the 3-year burning. This fraction can represent an important reserve of P (legacy) for the crops, reducing the use of phosphate mineral fertilizers over the years. Our findings are important for the selection and implementation of efficient and sustainable sugarcane cultivation systems, with implications for the ethanol i