Dinâmica de formas de fósforo em Latossolo Vermelho Distrófico psamítico sob efeito de calagem e adubação fosfatada, em área de expansão de cana-de-açúcar

Abstract

Phosphorus (P) is an essential nutrient for the development and productivity of sugarcane, but its natural availability in tropical soils is limited due to the parent material and its high fixation capacity, which compromises crop nutrition. Sugarcane is one of Brazil's main agricultural commodities and finds favorable conditions for expansion in the Central-West region. However, the costs of amendments and fertilizers are high, and inadequate doses, sources, and application methods can limit agronomic and economic efficiency. In this context, management strategies such as liming, gypsum application, and corrective phosphate fertilization, combined with different incorporation methods, can contribute to improving nutrient availability and crop productivity. This study aimed to evaluate, under field conditions, the effects of liming, gypsum application and corrective phosphate fertilization, applied in different ways and at different depths, on soil phosphorus fractions, mineral nutrition and sugarcane productivity. The experiment was conducted on a psammitic Dystrophic Red Latosol in the municipality of Juti, Mato Grosso do Sul, using a randomized block design with split-plot and sub-split-plot arrangements. Management systems involving combinations of lime and gypsum rates and incorporation methods, different corrective phosphorus rates, and fertilizer sources applied in the planting furrow were evaluated. Soil and leaf samples were collected at different times, and soil P fractions, foliar P content, stalk yield (SHP), and sugar yield (SHP) were evaluated. The results showed that corrective phosphorus fertilization alone was not capable of increasing foliar P content to sufficient levels in either the cane plant or the first ratoon crop, demonstrating the strong phosphorus fixation in tropical soils. The average values remained below the range considered adequate (≥1.8–2.0 g kg⁻¹), characterizing persistent nutritional deficiency. Despite this, sugarcane and sugar productivity were significantly influenced by the management systems. The Traditional C system, which included more intensive soil preparation with deep plowing, harrowing, fractional liming, and gypsum application, promoted higher yields in the first harvest, regardless of the phosphorus corrective doses. This result was attributed to better incorporation and distribution of correctives and fertilizers, greater availability of Ca²⁺ and SO₄²⁻, reduced acidity and Al³⁺ toxicity, and improved root environment. In the first ratoon crop, a positive effect was observed from the combination of deep tillage (Traditional C) and localized fertilization with a soluble phosphorus source, resulting in greater tillering, vegetative vigor, and sucrose accumulation, reflected in gains in TCH and TAH. These results indicate that the productive response of sugarcane depends not only on the amount of phosphorus applied, but also on the application method and the chemical and physical conditions of the soil that favor nutrient uptake. Overall, it was concluded that phosphorus deficiency was consistent across all years and treatments, but productivity was more sensitive to integrated soil fertility management than to the isolated application of P amendments. Strategies that combined liming, gypsum application, deep tillage, and localized fertilization proved more effective in enhancing nutrient uptake and sustaining sugarcane productivity. These results reinforce the need for integrated, medium-term management to overcome the low phosphorus availability in highly weathered tropical soils, ensuring greater efficiency in the use of inputs and the sustainability of sugarcane fields.