Olive cultivation (Olea europaea L.) covers approximately 11 million hectares worldwide and has been expanding in Brazil as an alternative for agricultural diversification. The intensification of production systems has increased productivity but has also intensified the extraction of nutrients from the soil. In this context, soil organic matter (SOM) stands out as an essential component for maintaining soil quality. Its most labile fractions are particularly sensitive to changes in management practices and serve as important indicators of soil quality. Despite this, information on the dynamics of organic carbon in olive cultivation systems remains limited, especially in Brazil. Thus, this study aims to evaluate changes in soil organic matter and chemical properties under olive cultivation (CA) and forest cover (FA) in the Serra da Mantiqueira region. Four deformed composite soil samples were collected from 0-5, 5-10, 10-20, and 20-40?cm layers. Soil fertility, including macronutrients and micronutrients, and soil organic carbon (SOC) were evaluated. For macronutrients (K, Ca, Mg), the application of mineral fertilizers resulted in the highest values in the CA profile compared to the FA. However, for the micronutrients (Cu and Fe), the highest values were concentrated in the superficial soil layer in FA. SOM values ranged from 1.38 to 3.49 g kg?¹, with the lowest value observed in area CA 5-10 and the highest in area FA 0-5. SOC ranged from 8.97 (CA 20-40) to 26.16 g kg?¹ (FA 0-5). The conversion of forest land to olive orchards induces changes in soil chemical properties, often enhancing nutrient availability. Nevertheless, declines in soil organic carbon (SOC) can negatively affect soil quality, highlighting the need for conservation practices (e.g., mulching) to support the restoration of soil carbon stocks.

The application of boron in soybeans in Oxisols of the Brazilian Cerrado is frequently integrated into complex tank fertilizer mixtures with multiple components via foliar application. This study investigated the interactive effects of varying spray application rates (40, 70, 100, and 130 L ha-1) and adjuvant types (organosilicone surfactant; methylated seed oil; and a water control) on boron deposition and the resulting physiological status. The organosilicone surfactant provided superior technical stability and deposition efficiency, allowing for a reduction in application rates to volumes between 40 and 70 L ha-1 maintaining a stable foliar B status across the evaluated range. In contrast, the performance of the methylated oil was strictly dependent on physical deposition, being effective only at intermediate rates, while the use of water alone represented a high risk of technical failure at reduced volumes. Furthermore, the NDRE index proved to be more responsive and robust than NDVI for monitoring delivery efficiency in high-density canopies, as it avoided signal saturation. Finally, Multivariate Analysis helped to observe that soybean yield in the Cerrado is primarily governed by the mitigation of water and thermal stress (TVDI), with optimized boron application acting as a key facilitator of reproductive success and yield stability under these environmental constraints.