Physicochemical characterization of the first 5 millimeters of precipitation obtained from a sampler for use in irrigation of urban agriculture in Tangará da Serra, Mato Grosso, Brazil

Abstract

Analyzing the quality of rainwater to use it in agricultural practices in the urban region of Tangará da Serra, Mato Grosso, is essential as urban development strategies, since the municipality has faced a water crisis in recent years. Thus, the present work aimed to classify the quality of the first five millimeters of rainwater to understand the condition of initial disposal, evaluating the feasibility of its use in the irrigation of urban agriculture according to the guidelines of the United Nations Food and Agriculture Organization (FAO), as well as the possible generating sources of the chemical compounds measured. To this end, laboratory and statistical analyses of rainwater quality parameters were carried out, such as: hydrogenionic potential, bicarbonates, electrical conductivity, total dissolved salts, calcium, magnesium, total hardness, chlorides, sodium and potassium, from samples collected from October 2019 to April 2020. The results showed that the concentrations of the chemical compounds evaluated were higher in the initial millimeter of rain, improving water quality throughout the precipitation. The classification carried out with the FAO guidelines pointed out that there is no restriction on the use of rainwater in the municipality for irrigation of urban agriculture. However, it is possible that both natural and anthropogenic sources influenced the concentrations of monitored chemical compounds. Thus, as the local atmosphere can provide elements that are related to the alteration of the natural characteristics of rainwater, the disposal of the initial millimeters and the use of this water is a viable option for the irrigation of species cultivated in the building’s backyard.