Terraços com cultivo irrigado na recuperação de áreas degradadas na geração de serviços ambientais

Abstract

The Brazilian semiarid, being a region marked by water scarcity scenarios, found new development perspectives in irrigated agriculture, however, it has suffered over the years the impacts of poorly managed agricultural activities. The theme of environmental services brings new perspectives of coexistence between production in irrigated agriculture and the preservation of the environment, ensuring sustainability and balance. Therefore, the objective of this research is to use agro- hydrological modeling to verify whether irrigation associated with conservation practices, as a technique adopted in the agricultural activity, is capable of promoting the achievement of environmental services in the hydrographic basin of the middle Salitre in the Brazilian semiarid region. The experimental site is divided into two areas: recovered and degraded, and located in Campo Formoso, Bahia, Brazil. The recovered area corresponds to an area with the presence of a terrace with two levels and cultivated with irrigated grass, next to it is the degraded area with 12% slope towards the river bed, exposed soil and presence of gullies. Between January 17 and April 28, 2019, the meteorological monitoring of the variables: temperature, precipitation, relative humidity, wind speed and solar radiation was carried out at the study site, through the installation of a complete climatological station, as well as the humidity in the ground through electronic sensors. Sensors were manufactured and calibrated in the laboratory. Samples of deformed and undisturbed soils from both areas were collected at depths of 0-25 cm and 25-50 cm for analysis of chemical and physical soil quality indicator properties and organic matter content. The Hydrus 1D Agro- hydrological model was used to establish the hydraulic properties of the soil via inverse modeling through an evaporation experiment in a greenhouse. The SWAP hydrological model was used to simulate the water balance in the study areas. The results demonstrate that the sensors calibration was efficient to represent, with reliability, the humidity variations until the field capacity. In the soil analysis, it is observed that the soil in the recovered area has better physical and chemical quality, although there are no differences in the organic matter content between the areas. As for the hydraulic properties, the soil in the recovered area presents greater water retention at a depth of 0-25 cm and a lower value of hydraulic conductivity (Ks), when compared to the soil in the degraded area. There are no retention differences between the areas for depths of 25-50 cm, and the recovered area has higher Ks. The differences observed in the water balance between the study areas made it possible to demonstrate the relevance of management and irrigation in improving environmental conditions in the recovered area, which positively and directly implies gains for the ecosystem. Only in soil water storage the recovered area presented 29.41% more than the degraded area. The improvement of environmental conditions could be qualified through the indication of regulatory ecosystem services linked to it.