Avaliação das perdas de solo e água por erosão hídrica laminar em área com pastagem degradada submetida a restauração da Floresta Atlântica, com plantio de mudas e adubação verde, Mendes - RJ

Abstract

The Payment for Environmental Services (PES) for water has been established as a political and economic instrument over the last two decades in Brazil, with the premise of guaranteeing or recovering the Ecosystem Services (ES) provided by nature. Although the expansion of water PES programs throughout the national territory is a reality, their monitoring and use of methodologies capable of evaluating the real results generated are still not comprehensive and efficient. This research aimed to evaluate the effect of different forest restoration strategies on physical and chemical indicators of soil quality and hydro-sedimentological parameters, such as surface runoff, soil loss rate and matrix suction on a property covered by the Project: “Produtores de Água e Floresta” (PAF) Sub-Basin of the Sacra Família River, in the municipality of Mendes in the state of Rio de Janeiro. The methodology consisted of installing Wischmeier model erosion control plots in dimensions 22mx4m connected to 1000L water tanks, together with pluviometers and GMS sensors, where four different treatments were adopted in order to compare: total planting, total planting with green manure, fallow and exposed soil. To obtain the runoff volumes generated, a calibration test of the tanks used was carried out, generating a linear regression applicable to the value of the measurements obtained in the field. The determination of soil loss and its properties was obtained through laboratory analyzes for: texture, soil and particle density, porosity, stability of aggregates and organic matter, adopting the analysis of variance (ANOVA) and Tukey Test for interpretation of these. The result of the soil analysis in (T0) indicated that in the study area the soils have predominantly clayey and sandy-clay granulometry, the average density of the soil before planting was (1.64 g/cm³), as well as particle density (2.67 cm³), porosity (38.56%), organic matter content (18.09 g/kg-1) and its aggregation index (83.12%). The parameters monitored in the plots referring to the runoff, the rate of soil loss and the matrix suction showed the contribution of the different strategies adopted throughout the experiment, indicating that the change in the type of land use has a great influence on the behavior of these parameters. One year after the beginning of the forest restoration, with the result of new analyses, it was concluded that in general there was a reduction in the soil density, as well as an increase in the total porosity, however, a reduction in the stability index of the aggregates and in the organic matter of all plots analyzed. Therefore, the potential of this study is linked to the provision of subsidies related to monitoring in water PES projects, in such a way that it is possible to outline more comprehensive methodologies that help in the valuation of environmental services.