Nutrient content, acidity, and soil texture in areas degraded by mining in the biogeographic Chocó

Abstract

Mining is one of the economic activities that most destroy ecosystems in the biogeographic Chocó. Therefore, it is necessary to know the effects of mining on the physicochemical conditions of the soil with a view to its restoration. In this context, in the present study, we evaluated the changes in the edaphic conditions of areas degraded by mining with different successional ages in the region. For this, five permanent plots of 625 and 2,500 m2 were established in the areas with 15 and 30 years of recovery, respectively. Subsequently, composite soil samples were taken at a depth of 20 cm to determine their nutrient contents, pH, and texture. We found that the soils were acidic (pH = 4.73), with a high percentage of sand, organic matter (OM) (6.62%), total N (0.34%), available P (28.21 ppm ), K (0.38 meq/100 g), and Al (2.15 meq/100 g) but with low amounts of Ca (2.28 meq/100g) and Mg (1.37 meq/100 g). Furthermore, the availabilities of P and K were high in both successional ages whereas the OM, total N, Ca, Mg, effective cation exchange capacity (ECEC), Al, and the percentage of sand increased with the succession while the pH and the clay decreased. In summary, an increase in the availability of sand and nutrients was evidenced but also an increase in acidity and Al toxicity with the succession. Likewise, we confirmed that the recovery of the physicochemical conditions of the soil in mines is conditioned by the effect of organic matter and vegetation.