Impact of climate on mineralogy and formation of Luvisols in Borborema province, northeastern Brazil

Approximately 3.6 million people in the semi-arid region of Brazil depend on agriculture, making it highly susceptible to climatic impacts. Luvisols are highly fertile soils in this region, with irregular rainfall patterns. However, the effect of climate on the development of these soils has not yet been thoroughly studied. We intended to illustrate how variations in rainfall quantity influence the formation of Luvisols, thereby affecting soil morphology and mineral composition. Three Luvisol profiles were morphologically described, sampled for physical, chemical, mineralogical, and micromorphological analyses, and classified under different mean annual precipitation (415, 673, and 777 mm) and evapotranspiration (1447, 1335, and 1220 mm) conditions. The results obtained showed that argillation, rather than clay illuviation, is the predominant process in Luvisol formation under different rainfall conditions. Pedogenetic processes were consistent across all soils but were enhanced by increased rainfall, leading to alterations in soil morphology. Soil color is affected by rainfall, resulting in a reddish hue in a wetter environment because of the higher amount of pedogenic oxides created. Luvisols in dry areas feature prominent cracks due to the prevalence of smectites, whereas in wetter regions, they are mainly kaolinitic and do not exhibit any cracks, implying that Luvisols formed under higher precipitation conditions have better potential for agricultural use.