Physical, chemical and mineralogical characteristics of soils from the meadows of Sousa (Paraíba State – Brazil) were studied, as well as the effect of alkaline and alkaline-earthy cations on humic substance stability. Furthermore, criteria of environmental distinction used by the small farmers and different forms of land use in the studied region were identified. Profiles from the classes Ustifluvents (Neossolo Flúvico), Haplustalfs (Luvissolo), Natrustalfs (Planossolo nátrico), and Usterts (Vertissolo crómico) were therefore selected, sampled and analyzed. Besides sodium, magnesium also […]