Variabilidade espacial de atributos do solo e dinâmica da cobertura vegetal após queima acidental em área de sucessão soja-milho

Abstract

Accidental fires in agricultural areas can alter soil chemical, physical, and biological properties, potentially compromising soil quality and the sustainability of agricultural production systems. In this context, this study aimed to evaluate the effects of an accidental fire on soil properties and vegetation cover dynamics in an area under a long-term no-tillage system. The study was conducted in Dourados, Mato Grosso do Sul, Brazil, in an agricultural area under soybean–maize succession for more than 15 years. A total of 50 georeferenced sampling points were systematically distributed across a regular grid, including 18 points in the burned area and 32 in the unburned area. Soil samples were collected at depths of 0–10 and 10–20 cm approximately 11 months after the fire to determine soil chemical and physical properties and acid phosphatase activity. The spatial variability of soil properties was assessed using geostatistical analysis, while vegetation cover dynamics were evaluated using the Normalized Difference Vegetation Index (NDVI), derived from Sentinel-2 satellite imagery acquired before and after the fire and during the establishment of the subsequent crop. The results revealed few differences in soil properties between burned and unburned areas, with no statistically significant differences in the evaluated physical properties. Acid phosphatase activity showed a numerical reduction in the burned area, although this difference was not statistically significant. Geostatistical analysis revealed predominantly strong to moderate spatial dependence among the evaluated soil properties. Temporal NDVI analysis indicated a reduction in vegetation cover associated with the fire, followed by recovery after the establishment of the soybean crop. In conclusion, under the conditions evaluated, the accidental fire had limited effects on soil properties 11 months after its occurrence, although it caused temporary changes in vegetation cover.