Soil remineralization and recovery of degraded areas: an experience in the tropical region

Descrição

Many activities related to the expansion of food supply, energy and infrastructure result in great environmental impacts, whose most visible features are observed in the degradation of large areas. The present study demonstrates how the combined use of stonemeal technology and agroforestry systems can help to reverse such impacts, allying the recovery of degraded areas with agricultural and forest production. The study area is located in a hydroelectric reservoir affected by the siltation process and soil erosion in the hydrographic basin of the San Francisco River, Brazil. An Experimental Unit (EU) was set up in the Ecological Station of Pirapitinga (Três Marias reservoir). The design of the EU was based on a factorial design, with seven treatments applied on six native tree species, with three replications (21 blocks). The germination and establishment data of each species were considered in the different treatments. The oxides concentration and fertility level of sediments were analyzed for the determination of the sampling points in the reservoir. The experiment and evaluation were conducted over six years, and the sediments analysis presented high levels of the essential macronutrients K2O, MgO and TiO2, while CaO and Na2O levels were significantly low, due to their high solubility and mobility. The P2O5 also showed equally low values. After two years, soil pH was balanced, especially in the blocks with mineral inputs. P, K, Ca and Mg concentrations were increased up to 5 times more than those of original soil of the EU, and the highest values were found in the remineralizer + sediment treatment. The use of geological material (e.g. mining waste) and organic compost was proved to be an adequate and sustainable technology to mitigate degradation processes. Besides, locally available sources of organic matter enhanced.