scholarly journals Analysis of the Variability in Soil Moisture Measurements by Capacitance Sensors in a Drip-Irrigated Orchard

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5100
Author(s):  
Jesús María Domínguez-Niño ◽  
Jordi Oliver-Manera ◽  
Gerard Arbat ◽  
Joan Girona ◽  
Jaume Casadesús
Keyword(s):  
Soil Moisture ◽  
Low Cost ◽  
Natural Variability ◽  
Water Dynamics ◽  
Virtual Sensors ◽  
Soil Moisture Sensors ◽  
Order Of Magnitude ◽  
Recorded Data ◽  
Maintenance Requirements ◽  
Possible Cause

Among the diverse techniques for monitoring soil moisture, capacitance-type soil moisture sensors are popular because of their low cost, low maintenance requirements, and acceptable performance. However, although in laboratory conditions the accuracy of these sensors is good, when installed in the field they tend to show large sensor-to-sensor differences, especially under drip irrigation. It makes difficult to decide in which positions the sensors are installed and the interpretation of the recorded data. The aim of this paper is to study the variability involved in the measurement of soil moisture by capacitance sensors in a drip-irrigated orchard and, using this information, find ways to optimize their usage to manage irrigation. For this purpose, the study examines the uncertainties in the measurement process plus the natural variability in the actual soil water dynamics. Measurements were collected by 57 sensors, located at 10 combinations of depth and position relative to the dripper. Our results showed large sensor-to-sensor differences, even when installed at equivalent depth and coordinates relative to the drippers. In contrast, differences among virtual sensors simulated using a HYDRUS-3D model at those soil locations were one order of magnitude smaller. Our results highlight, as a possible cause for the sensor-to-sensor differences in the measurements by capacitance sensors, the natural variability in size, shape, and centering of the wet area below the drippers, combined with the sharply defined variation in water content at the soil scale perceived by the sensors.

scholarly journals Tree Water Dynamics in a Semi-Arid, Pinus brutia Forest

Water ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 1039 ◽  
Author(s):  
Marinos Eliades ◽  
Adriana Bruggeman ◽  
Hakan Djuma ◽  
Maciek Lubczynski
Keyword(s):  
Soil Moisture ◽  
Sap Flow ◽  
Water Dynamics ◽  
Hydraulic Redistribution ◽  
Sap Flux ◽  
Sap Flux Density ◽  
Pinus Brutia ◽  
Soil Moisture Sensors ◽  
Air Temperatures ◽  
Semi Arid

This study aims to examine interactions between tree characteristics, sap flow, and environmental variables in an open Pinus brutia (Ten.) forest with shallow soil. We examined radial and azimuthal variations of sap flux density (Jp), and also investigated the occurrence of hydraulic redistribution mechanisms, quantified nocturnal tree transpiration, and analyzed the total water use of P. brutia trees during a three-year period. Sap flow and soil moisture sensors were installed onto and around eight trees, situated in the foothills of the Troodos Mountains, Cyprus. Radial observations showed a linear decrease of sap flux densities with increasing sapwood depth. Azimuthal differences were found to be statistically insignificant. Reverse sap flow was observed during low vapor pressure deficit (VPD) and negative air temperatures. Nocturnal sap flow was about 18% of the total sap flow. Rainfall was 507 mm in 2015, 359 mm in 2016, and 220 mm in 2017. Transpiration was 53%, 30%, and 75%, respectively, of the rainfall in those years, and was affected by the distribution of the rainfall. The trees showed an immediate response to rainfall events, but also exploited the fractured bedrock. The transpiration and soil moisture levels over the three hydrologically contrasting years showed that P. brutia is well-adapted to semi-arid Mediterranean conditions.

scholarly journals Hydrotropic Root Behavior in Water-Saving Cultivation: A High-Resolution Monitoring Study of Soil Water Dynamics

2021 ◽  
Author(s):  
Qichen Li ◽  
Toshiaki Sugihara ◽  
Sakae Shibusawa ◽  
Minzan Li
Keyword(s):  
Soil Moisture ◽  
High Resolution ◽  
Water Content ◽  
Root System ◽  
Soil Water ◽  
Water Saving ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Soil Moisture Sensors ◽  
Wet Zone

Abstract BackgroundSubsurface irrigation has been confirmed to have high water use efficiency due to it irrigating only the crop root zone. Hydrotropism allows roots to grow towards higher water content areas for drought avoidance, which has research interests in recent years. However, most hydrotropism studies focused on a single root and were conducted in air or agar systems. The performance of hydrotropism in subsurface irrigation is not clear. ResultsWe developed a method to observe and analyze hydrotropism in soil under water-saving cultivation. A wet zone was produced around the whole root system based on using subsurface irrigation method and micro soil water dynamics were observed using high-resolution soil moisture sensors. This method enabled the observation and analysis of plant water absorption activities and the hydrotropic response of the root system. In the analysis, we first applied a high-pass filter and fast Fourier transform to the soil water dynamics data. The results indicated that the plant’s biological rhythm of photosynthetic activities can be identified from the soil moisture data. We then observed root growth in response to the dynamics of soil water content in the wet zone. We quantified root distribution inside and outside the wet zone and observed the shape of the root system from the cross-section of the wet zone. The results showed that the root hydrotropic response is not uniform for all roots of an individual plant. ConclusionsThis study verified the feasibility of using high-resolution soil moisture sensors to study root hydrotropic responses in soil during water-saving cultivation. To further evaluate a plant’s hydrotropic ability, it is necessary to use statistical analysis and/or a non-deterministic approach. Future studies may also explore developing an automated experimental system and robotic manipulations for getting steady repeatable observation of hydrotropism in water-saving cultivation.

Impact of soil wetness on plant litter decomposition using low-cost soil moisture sensors and off-the-shelf tea bags

2020 ◽  
Author(s):  
Angelika Xaver ◽  
Taru Sandén ◽  
Heide Spiegel ◽  
Luca Zappa ◽  
Gerhard Rab ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Moisture ◽  
Soil Organic Matter ◽  
Litter Decomposition ◽  
Environmental Variables ◽  
Low Cost ◽  
Plant Litter ◽  
Soil Moisture Sensors ◽  
Plant Litter Decomposition ◽  
The Relationship

<p>Soil organic matter plays a key role within the nutrient cycle, serves as an agent to improve soil structure, and is also known to impact concentrations of greenhouse gases and stabilize soil pollutants. Thus, the soil organic matter content and its potential losses through decomposition are of high interest, especially in the light of a changing climate. As the decomposition process is significantly influenced by climatic conditions, it is important to understand the relationship between decomposition and environmental variables. Previous studies primarily focused on determining the influence of air temperature and precipitation on litter decomposition, but the impact of soil moisture has hardly been investigated.</p><p>In this study, we evaluate the relationship between plant litter decomposition, using commercial tea bags (Green and Rooibos tea) as standardized plant litter, and soil moisture, observed with low-cost sensors used within the European citizen science project GROW Observatory (GROW; https://growobservatory.org/). The low-cost soil moisture sensors were placed alongside the tea bags at eight different locations, covering four different land cover types, within the Hydrological Open Air Laboratory (HOAL), a small agricultural catchment in Petzenkirchen, Austria. Data has been collected for two years providing decomposition rates (k) and stabilization factors (S) for the four different seasons of both years. Apart from soil moisture, we investigate air and soil temperature, precipitation and soil parameters as drivers for litter decomposition.</p><p>We will show preliminary results on the relationship between decomposition and different environmental variables, in particular soil moisture, throughout all seasons and various land cover classes.</p><p> </p><p>This study was funded by the GROW Observatory project of the European Union’s Horizon 2020 research and innovation programme (https://growobservatory.org/).</p>

scholarly journals Monitoring and Controlling Ebb-and-flow Subirrigation with Soil Moisture Sensors

HortScience ◽  
2015 ◽  
Vol 50 (3) ◽  
pp. 447-453 ◽  
Author(s):  
Rhuanito Soranz Ferrarezi ◽  
Marc W. van Iersel ◽  
Roberto Testezlaf
Keyword(s):  
Soil Moisture ◽  
Nutrient Solution ◽  
Water Movement ◽  
Water Dynamics ◽  
Data Logger ◽  
Bottom Part ◽  
Shoot Height ◽  
Nutrient Runoff ◽  
Soil Moisture Sensors ◽  
Ebb And Flow

Subirrigation can reduce water loss and nutrient runoff from greenhouses, because used nutrient solution is collected and recirculated. Capacitance moisture sensors can monitor substrate volumetric water content (θ) and control subirrigation based on minimum θ thresholds, providing an alternative to timers. Our objectives were to automate an ebb-and-flow subirrigation system using capacitance moisture sensors, monitor moisture dynamics within the containers, and determine the effect of five θ thresholds (0.10, 0.18, 0.26, 0.34, or 0.42 m3·m−3) on hibiscus (Hibiscus acetosella Welw. ex Hiern.) ‘Panama Red’ (PP20,121) growth. Subirrigation was monitored using capacitance sensors connected to a multiplexer and a data logger and controlled using a relay driver connected to submersible pumps. As the substrate θ dropped below the thresholds, irrigation was turned on for 3 min followed by 3-min drainage. Capacitance sensors effectively controlled subirrigation by irrigating only when substrate θ dropped below the thresholds. Each irrigation cycle resulted in a rapid increase in substrate θ, from 0.10 to ≈0.33 m3·m−3 with the 0.10-m3·m−3 irrigation threshold vs. an increase in θ from 0.42 to 0.49 m3·m−3 with the 0.42-m3·m−3 irrigation threshold. Less nutrient solution was used in the lower θ threshold treatments, indicating that sensor control can reduce water and thus fertilizer use in subirrigation systems. The water dynamics showed that the bottom part of the pots was saturated after irrigation with θ decreasing quickly after an irrigation event, presumably because of drainage. However, the water movement among substrate layers was slow with the 0.10-m3·m−3 irrigation threshold with water reaching the upper layer 5.5 to 20 h after irrigation. The 0.10-m3·m−3 θ threshold resulted in 81% fewer irrigations and 70% less nutrient solution use compared with the 0.42-m3·m−3 θ threshold. However, the 0.10-m3·m−3 θ threshold also reduced hibiscus shoot height by 30%, shoot dry weight 74%, and compactness by 63% compared with the 0.42-m3·m−3 θ threshold. Our results indicate that soil moisture sensors can be used to control subirrigation based on plant water use and substrate water and to manipulate plant growth, thus providing a tool to improve control over plant quality in subirrigation systems.

scholarly journals Monitoring and Management of Pecan Orchard Irrigation: A Case Study

2006 ◽  
Vol 16 (4) ◽  
pp. 667-673 ◽  
Author(s):  
Jeffery C. Kallestad ◽  
Theodore W. Sammis ◽  
John G. Mexal ◽  
John White
Keyword(s):  
Soil Moisture ◽  
Root Zone ◽  
Low Cost ◽  
Graphical Analysis ◽  
Irrigation Scheduling ◽  
Soil Moisture Sensors ◽  
Scheduling Model ◽  
Inflection Points ◽  
Moisture Extraction ◽  
Use Of Internet

Optimal pecan (Carya illinoiensis) production in the southwestern United States requires 1.9 to 2.5 m of irrigation per year depending on soil type. For many growers, scheduling flood irrigation is an inexact science. However, with more growers using computers in their businesses, and with soil moisture sensors and computerized data-collection devices becoming more inexpensive and accessible, there is potential to improve irrigation and water use efficiencies. In this project two low-cost soil monitoring instruments were introduced to a group of pecan producers. They were also given instruction on the use of Internet-based irrigation scheduling resources, and assistance in utilizing all of these tools to improve their irrigation scheduling and possibly yield. The objectives were to determine whether the technology would be adopted by the growers and to assess the performance of the sensors at the end of the season. Three out of the five growers in the project indicated they used either the granular matrix (GM) sensors or tensiometer to schedule irrigations, but compared to the climate-based irrigation scheduling model, all growers tended to irrigate later than the model's recommendation. Graphical analysis of time-series soil moisture content measured with the GM sensors showed a decrease in the rate of soil moisture extraction coincident with the model's recommended irrigation dates. These inflection points indicated the depletion of readily available soil moisture in the root zone. The findings support the accuracy of the climate-based model, and suggest that the model may be used to calibrate the sensors. Four of the five growers expressed interest in continued use of the tensiometer, but only one expressed a desire to use the GM sensor in the future. None of the participants expressed interest in using the climate-based irrigation scheduling model.

scholarly journals Smart Farm Irrigation: Model Predictive Control for Economic Optimal Irrigation in Agriculture

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1810
Author(s):  
Gabriela Cáceres ◽  
Pablo Millán ◽  
Mario Pereira ◽  
David Lozano
Keyword(s):  
Soil Moisture ◽  
Energy Consumption ◽  
Crop Yields ◽  
Low Cost ◽  
Water Dynamics ◽  
Sensors And Actuators ◽  
Predictive Controller ◽  
Farm Scale ◽  
Different Depths

The growth of the global population, together with climate change and water scarcity, has made the shift towards efficient and sustainable agriculture increasingly important. Undoubtedly, the recent development of low-cost IoT-based sensors and actuators offers great opportunities in this direction since these devices can be easily deployed to implement advanced monitoring and irrigation control techniques at a farm scale, saving energy and water and decreasing costs. This paper proposes an economic and periodic predictive controller taking advantage of the irrigation periodicity. The goal of the controller is to find an irrigation technique that optimizes water and energy consumption while ensuring adequate levels of soil moisture for crops, achieving the maximum crop yield. For this purpose, the developed predictive controller makes use of soil moisture data at different depths, and it formulates a constrained optimization problem that considers energy and water costs, crop transpiration, and an accurate dynamical nonlinear model of the water dynamics in the soil, reflecting the reality. This controller strategy is compared with a classical irrigation strategy adopted by a human expert in a specific case study, demonstrating that it is possible to obtain significant reductions in water and energy consumption without compromising crop yields.

scholarly journals Applicability of soil moisture sensors for monitoring water dynamics in rock: A field test in weathered limestone

2021 ◽  
Author(s):  
Pedro A. M. Leite ◽  
Bradford P. Wilcox ◽  
Kevin J. McInnes ◽  
John W. Walker
Keyword(s):  
Soil Moisture ◽  
Field Test ◽  
Water Dynamics ◽  
Soil Moisture Sensors

scholarly journals A Wireless Sensor Network Deployment for Soil Moisture Monitoring in Precision Agriculture

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7243
Author(s):  
Jaime Lloret ◽  
Sandra Sendra ◽  
Laura Garcia ◽  
Jose M. Jimenez
Keyword(s):  
Soil Moisture ◽  
Wireless Sensor Network ◽  
Sensor Network ◽  
Precision Agriculture ◽  
Low Cost ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
Received Signal Strength Indicator ◽  
Soil Moisture Sensors ◽  
The Cost

The use of precision agriculture is becoming more and more necessary to provide food for the world’s growing population, as well as to reduce environmental impact and enhance the usage of limited natural resources. One of the main drawbacks that hinder the use of precision agriculture is the cost of technological immersion in the sector. For farmers, it is necessary to provide low-cost and robust systems as well as reliability. Toward this end, this paper presents a wireless sensor network of low-cost sensor nodes for soil moisture that can help farmers optimize the irrigation processes in precision agriculture. Each wireless node is composed of four soil moisture sensors that are able to measure the moisture at different depths. Each sensor is composed of two coils wound onto a plastic pipe. The sensor operation is based on mutual induction between coils that allow monitoring the percentage of water content in the soil. Several prototypes with different features have been tested. The prototype that has offered better results has a winding ratio of 1:2 with 15 and 30 spires working at 93 kHz. We also have developed a specific communication protocol to improve the performance of the whole system. Finally, the wireless network was tested, in a real, cultivated plot of citrus trees, in terms of coverage and received signal strength indicator (RSSI) to check losses due to vegetation.

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