Desenvolvimento de sensores microcontrolados para avaliação da umidade e temperatura do solo

Abstract

Precision agriculture is an emerging concept whose main objective is to optimize the management of agricultural activities by observing, measuring and responding to the temporal and spatial variations of the crops, through the implementation of technologies in the field such as geolocation, sensing and control. In this sense, this study aimed to develop a soil moisture measurement system composed of three steps: smart soil moisture sensors, concentrator unit and monitoring unit. This system aims to assist in the monitoring of rural properties and the segmented management of water resources. The soil moisture sensors consist of an analog circuit, two probes and a temperature sensor. The capacitive method of measurement is applied, in which soil moisture is obtained from the dielectric constant and the capacitance of the electrode-soil matrix. The developed sensor presented error less than 3%, with correlation coefficient of 0.9785. The concentrator unit allows the connection of multiple sensors and has the function of grouping the data referring to the humidity and temperature of each one. The monitoring unit aims to enable remote monitoring of the concentrator unit by the implementation of a long-distance wireless communication link, eliminating the need of physical access to obtain the data. Link tests were performed with a max distance of 2.41 km in an urban region and 5.39 km in a rural region.