Relaciones matemáticas entre la resistencia mecánica a la penetración y el contenido hídrico en un suelo inceptisol

Abstract

The mechanical resistance to penetration (RPM) has become a method for identifying compacted soil layers for various reasons. The measurements made with the Field Scout 900 cone penetrometer, as well as the measurement of water content (θ) by means of the TDR 350 probe, stand out for providing real-time field information at low cost and for being easy to use equipment for producers or technicians in the agricultural sector. Technological advances provide new, precise and versatile equipment, with the advantage of being able to carry out several repetitions of data collection in situ in the rhizosphere of most crops, with little effort and in a short time. In Inceptisol soils, spatial variability together with temporal variability are interrelated to the physical properties and the water regime of the area, which can cause periods of contraction - dilation due to its predominant clayey texture. In the present work, mathematical relationships were established between RMP and soil water content of 5 profiles, considering strata of 05 cm in the first 10 cm, and in strata of 10 cm to 40 cm depth, of a plot with banana crop of the Santa Inés experimental farm of the Technical University of Machala, in the study of these 2 variables, 3 mathematical regression models were evaluated: linear, logarithmic and polynomial; with the water contents: volumetric moisture TDR; volumetric moisture by weight difference (θ_v), gravimetric moisture (θ_g), and saturated relative humidity (θ_v/θ_s ), determining that the mathematical model that best fits for all moisture contents in the first and last stratum (00-05 and 30-40) is the logarithmic one with an R^2 of 0. 649 and 0791 respectively; except for the case of θ_v TDR, where its R^2 was 0.602 and 0.705; it was also determined that the logarithmic model presents the best fit for θ_v: in the stratum from 10 to 20 cm with an R^2of 0.475. While for the remaining strata it was obtained that the polynomial model is the one that presents the best fit, being for θ_v TDR: stratum from 05 to 10 cm an R^2 0.618; stratum from 10 to 20 cm an R^2 of 0.692 and stratum from 10 to 20 cm an R^2 of 0.790. For θ_v: stratum from 05 to 10 cm an R^2 0.562; stratum from 20 to 30 cm an R^2 of 0.744. For θ_G: stratum from 05 to 10 cm an R^2 0.562; stratum from 10 to 20 cm an R^2 0.468 and stratum from 30 to 40 cm an R^2 0.775. For θ_v/θ_s: stratum from 05 to 10 cm an R^2 0.562; stratum from 10 to 20 cm an R^2 0.468 and stratum from 30 to 40 cm an R^2 0.860.