Evaluación de la sonda tdr para el seguimiento de la humedad de un suelo franco bajo el cultivo de banano

Abstract

In agriculture, water is a main factor that directly affects production, supplemental irrigation is applied to meet the water needs of crops in order not only to increase productivity, but also to reduce the inter-annual variability in crop yields, especially in the time when there is no more rainfall, taking into account these periods of low rainfall in the province of El Oro, because of this it is very important to know in real time the water content in the soil in order to understand the behavior of crops against variations in it. Among the methods for measuring water in the soil is the TDR capacitance probe, which is a direct measurement equipment that allows obtaining the moisture content in the soil in an accurate and instantaneous way. In order to determine an efficient irrigation water management in the banana farm "El Márquez" located in the parish La Peaña of the Pasaje canton, moisture content readings were taken during 12 weeks, geo-referencing each sampling site, data was taken every 15 days during the months of August to November, sampling and recording of readings was completely random throughout the farm, readings were taken with the TDR capacitance probe with 20cm long rods to obtain the volumetric water content in real time, for the comparison of the data, soil samples were taken at 20cm depth in the same sites, the gravimetric moisture content was determined, and considering its bulk density, its volumetric content was calculated in the soil laboratory of the University of Machala. For the determination of certain physical properties of the soil such as apparent density (Da), real density (Dr) and total porosity, the same soil samples were used. Thematic maps of the area were drawn with the water contents in the soil at 20 cm depth with the values obtained both with the TDR probe, as well as those obtained in the laboratory, using ArcGIS software, which allowed visualizing the various sectors with moisture content in the soil in August and September. With this information, it is possible to carry out an adequate planning of the agronomic design, calculating, among other things, the irrigation times and frequencies in each specific zone of the farm, helping to reduce the costs of applying the sheets due to the differences in moisture levels. To evaluate the behavior of the TDR probe readings with the values obtained by the gravimetric method, the Pearson correlation coefficient (0.991) was evaluated. The coefficient of determination (R^2=0.8298), and the linear regression equation (y= 1.033x-1.2015), indicating that the TDR probe in comparison with the gravimetric method, is a reliable instrument for the determination of the water film in the soil profile and is ideal for irrigation estimations.