Application of the TDR Sensor and the Parameters of Injection Irrigation for the Estimation of Soil Evaporation Intensity

Abstract

The objective of the study was to develop a precise method of determination of the evaporation rate in a soil irrigated with the use of a mobile injection irrigation system. Two methods of constructing functions approximating the value of evaporation have been developed. In the first method, the domain comprises the parameters of injection irrigation, i.e., the dose and the depth of injection, and in the second, the volumetric moisture of soil in the layer immediately below the soil surface, which was measured with time-domain reflectometry (TDR) sensors. For that purpose, a laboratory experiment was carried out, based on 12 physical models. The study was conducted on a natural soil material, with particle size distribution of its mineral parts corresponding to that of a loamy sand soil. It was demonstrated that evaporation intensity increases with irrigation and decreases with increase in the depth of water application. Using TDR sensors, it was also shown that evaporation intensity increases proportionally to the weighted arithmetic mean of the volumetric moisture. Comparison of the two methods indicates that the evaporation intensity of injection-irrigated soil can be estimated with higher accuracy when the domain of the approximating function is the injection depth and dose than when the domain of the function is the weighted mean of volumetric moisture of the surface horizon of the soil. However, the method using TDR sensors for the estimation of evaporation intensity of an injection-irrigated soil has a greater potential for the construction of universal approximating models. In addition, the advantage of the method based on the use of TDR sensors is that it uses arguments for the approximating function, f2θ, in real time.

Dynamics of Volumetric Moisture in Sand Caused by Injection Irrigation—Physical Model

“…The results had an identical character-the rate of soil moisture increase decreased with increasing distance from water emitters. Also, a similar character of the volumetric moisture changes was obtained during measuring the intensity of evaporation caused by induced irrigation [11]. In this work, the moisture content of the top layer of the monolith during a water injection was measured.…”

“…The bulk density of the monolith was 1.70 g•cm −3 , and porosity was 0.425 (-) [41]. Water application to the porous medium under high pressure was conducted with the use of a unique device developed by the MSINiN project team [11,42]. The device allows precise dosage of water with the accuracy of ±10% of the volume of the injected liquid [43], at a pressure corresponding to the conditions of the water supply network The key element of the device is the injector, with length of 20 cm, outer diameter of 1 cm and inner diameter of 0.5 cm.…”

“…The dimensions of the monolith, injec tion depth, and the volume of the applied water doses with the required outflow intensity were determined on the basis of the theoretical considerations presented in the introduction and verified in pilot experiments. Water application to the porous medium under high pressure was conducted with the use of a unique device developed by the MSINiN project team [11,42]. The device allows precise dosage of water with the accuracy of ±10% of the volume of the injected liquid [43], at a pressure corresponding to the conditions of the water supply network.…”

“…An increasing popularity is also observed in the case of water-saving drip lines, for which the area of use in 2030 will be doubled relative to that of 2000 [8]. Selected features of those irrigation systems became the base point for a concept of an injection irrigation system for crop plants, which is being realized within the framework of the project "Mobile system of injection irrigation and fertilisation meeting the individual requirements of the plant" by the consortium Mobile Irrigation and Fertilisation (MSINiN) [9][10][11]. The concept consists in subsurface application of a specific dose of water, within soil space containing plant root systems, which is characteristic of the subsurface drip line.…”

Combined Punctual and Diffused Monitoring of Concrete Structures Based on Dielectric Measurements

“…Microwave reflectometry is an electromagnetic (EM) measurement technique, employed for a number of diagnostics and monitoring applications. While one of the major application fields remains soil moisture content monitoring [ 29 , 30 , 31 , 32 ], this technique is also largely used for applications such as leak localization in underground pipes [ 33 , 34 , 35 ]; the characterization of devices [ 36 ]; etc.…”