To address the problems of soil acidity (pH values below 4.4) in surface and subsurface soil layers and improve soil chemical fertility, this study evaluated three methodologies for surface application of limestone (LS) (ensuring that calcium (Ca)²⁺ occupied 70%, 60% or 50% of cation exchange capacity (CEC) at a depth of 0.0–0.2 m) and gypsum (GP, phosphogypsum) (ensuring that Ca²⁺ occupied 60%, 50% or 40% of effective cation exchange capacity (ECEC) at a depth of 0.2–0.4 m). LS and GP were applied in a conventional pasture system (CPS), no-till system (NTS), and agropastoral system (APS) in an Arenic Hapludult in Brazil. Surface application of LS and GP using these three methodologies corrected surface and subsurface acidity and improved soil chemical fertility. Specifically, Ca²⁺ content increased in the CPS, NTS, and APS at a depth of 0.0–0.2 m and in the CPS and APS at a depth of 0.2–0.4 m; sulfur (S)-SO₄²⁻ content and Ca²⁺/ECEC increased in the CPS, NTS, and APS at a depth of 0.2–0.4 m; base saturation (BS) increased and aluminum (Al)³⁺ content decreased in the NTS and APS at depths of 0.0–0.2 m and 0.2–0.4 m; and pH, magnesium (Mg)²⁺ content, CEC, Ca²⁺/CEC, and Mg²⁺/CEC increased and total acidity decreased in the NTS and APS at a depth of 0.0–0.2 m.

This study aimed to evaluate which of five commonly used methodologies for agricultural gypsum application in no-tillage systems under tropical agricultural conditions is the most efficient in sandy soils. The evaluation focused on soil chemical and physical properties, nutrient movement through the soil profile, and crop productivity. Methods: Soil layers of 0–0.20 m and 0.20–0.40 m were analyzed. Data were subjected to analysis of variance, and means were compared using Student’s t-test (p < 0.05). Principal component analysis (PCA) and multivariate analysis were also performed. Results: An increase in calcium (Ca), potassium (K), and sulfur (S) contents was observed at the analyzed soil depths, along with a reduction in subsurface aluminum saturation (m%). Gypsum application also increased the dry matter yield of cover crops. Conclusions: For sandy soils under no-tillage systems with high nutrient export, aiming to improve soil fertility and aggregation, the gypsum application methodologies proposed by Caires and Guimarães or Raij and collaborators are recommended. According to multivariate analysis, these methodologies showed the best correlation with base saturation (V%), a key indicator of soil fertility. Additionally, the Caires and Guimarães method demonstrated a stronger correlation with maize productivity. However, none of the evaluated methodologies increased soybean yields.