Manejo da adubação fosfatada em cana-de-açúcar: efeitos de fontes de fertilizantes fosfatados na dinâmica do fosfóro em solo arenoso

Abstract

Brazil is the largest producer of sugarcane (Saccharum spp. L.; Poaceae), with approximately 8.2 million hectares cultivated in the 2022/2023 season, generating an estimated production of 625 million tons. This crop plays a crucial role in the economy, not only in sugar production but also in the generation of renewable energy and animal feed. In this context, efficient phosphorus (P) management in the soil becomes essential, since most Brazilian soils are naturally low in this nutrient. The experiment was conducted in a commercial area of a sugar-energy mill located in Monte Castelo, São Paulo State, Brazil, during two consecutive growing seasons (2020/21 and 2021/22). Two phosphorus sources were evaluated: conventional monoammonium phosphate (MAP) and polymer-coated monoammonium phosphate, applied at different rates and management strategies. Soil phosphorus availability was determined using the Ion Exchange Resin and Mehlich-1 extraction methods at different depths of the soil profile, in addition to evaluating the plant nutritional status and productive attributes. Chapter I presents the results related to soil phosphorus availability and the nutritional response of the crop as affected by phosphate fertilizer sources and rates. Chapter II discusses phosphorus lability in soil cultivated with sugarcane through the fractionation of different forms of the nutrient in the soil. The results show that the interaction between fertilizer sources, rates, and application methods significantly influences phosphorus dynamics in the soil, highlighting the potential of coated fertilizers to reduce adsorption reactions and increase nutrient use efficiency. Therefore, proper management of phosphorus fertilization is a key strategy to optimize phosphorus availability, promote greater agronomic efficiency, and contribute to more sustainable production systems in sugarcane cultivation.