The rapid development and wide application of the IoT (Internet of Things) has pushed toward the improvement of current practices in greenhouse technology and agriculture in general, through automation and informatization. The experimental and accurate determination of soil moisture is a matter of great importance in different scientific fields, such as agronomy, soil physics, geology, hydraulics, and soil mechanics. This paper focuses on the experimental characterization of a commercial low-cost “capacitive” coplanar soil moisture sensor that can be housed in distributed nodes for IoT applications. It is shown that at least for a well-defined type of soil with a constant solid matter to volume ratio, this type of capacitive sensor yields a reliable relationship between output voltage and gravimetric water content.

Soil erosion during rainfall events is affected by several factors, such as topography, soil type, land management, and vegetation cover. In this study, a series of tests investigates the influence of selected perennial herbaceous plants with a deep and strong rooting system, called MC1, on runoff generation and soil erosion. The tests on the investigated nature-based solution have been performed in the Cape Fear experimental hillslope with natural and artificial rainfall and for different vegetation heights. For all the experiments, runoff, soil moisture, and erosion data were observed and collected. The results obtained in this study suggest the following conclusions: (1) MC1 is effective in terms of soil erosion reduction already with a minimum vegetation height equal to 30 cm; (2) MC1 maximum efficiency, in terms of soil loss reduction, has been reached for a vegetation height equal to 70 cm; (3) In terms of the eroded material, the use of MC1 allows for a reduction of soil loss up to 300 times higher than the bare soil condition; (4) The use of MC1 allows for a reduction in the runoff coefficient up to 1/3 of the corresponding value in the bare soil condition.

The use of low-cost embedded devices with ubiquitous connectivity systems is a possible strategy to monitor the consumption of water used in agriculture even in countries that do not have good economic resources. In this paper, we propose a low-cost system based on a measuring approach of capacitive soil water content sensors never explored previously. This solution takes advantage of the sensor properties to respond to the need to measure at the same time salinity and soil volumetric water content. For this purpose, a bi-functional system based on a modified commercial capacitive sensor and an AD5933 impedance converter integrated circuit is described. The considered frequency range for impedance measurements is 10-100 kHz, which is a “low-frequency” range compared with typical operating frequencies of professional systems devoted to water content measurements. Measurements are carried out to check the system accuracy and to characterize the impedance of the sensor both in the air and in water, which represent the two boundaries of possible operating conditions in physical soils in terms of the real part of the electrical permittivity. Variations of the imaginary part of the electrical permittivity are taken into account using water with conductivity between 1 and 2300 μS/cm. Experimental results are compared with the measurements obtained by using a laboratory LCR meter and a maximum error of +6.12% for the capacitance and +5.6% for the conductance is obtained. The proposed system is also employed to characterize silica sandy soil with different water contents and conductivities showing quite promising results useful to overcome the well-known limits of low-cost soil water content sensors.