Metode za merjenje vsebnosti vode v tleh

Water has a significant influence on fundamental biophysical processes in the soil. It is one of the limiting factors for plant growth, which is why monitoring the water content in the field is particularly important in agriculture. In this article we present the methods currently used to measure the soil water content. We have described their functional principles, advantages, disadvantages and possible applications. Due to their widespread use in agriculture, we have focused on dielectric sensors, which are classified as electromagnetic methods. We have investigated the influence of soil properties on measurements with dielectric sensors and described possible methods for soil-specific calibration. In agriculture and environmental sciences, measurements of soil water content are particularly important for irrigation management. Irrigation based on measurements enables us to optimize the use of water resources and reduce the negative impact on the environment. For the correct functioning of such sensors it is necessary to check the suitability of the factory calibration function. Special attention is required when installing the sensors, as the presence of air gaps causes errors in the measurements.

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Time series outlier and intervention analysis: Irrigation management influences on soil water content in silty loam soil

Agricultural Water Management ◽

10.1016/j.agwat.2012.05.008 ◽

2012 ◽

Vol 111 ◽

pp. 105-114 ◽

Cited By ~ 12

Author(s):

Basem Aljoumani ◽

Jose A. Sànchez-Espigares ◽

Nuria Cañameras ◽

Ramon Josa ◽

Joaquim Monserrat

Keyword(s):

Time Series ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Irrigation Management ◽

Intervention Analysis ◽

Silty Loam ◽

Loam Soil

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Evaluation of Improved Model to Accurately Monitor Soil Water Content

Water ◽

10.3390/w13233441 ◽

2021 ◽

Vol 13 (23) ◽

pp. 3441

Author(s):

Jingyu Ji ◽

Junzeng Xu ◽

Yixin Xiao ◽

Yajun Luan

Keyword(s):

Organic Matter ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Texture ◽

Irrigation Management ◽

Clay Fraction ◽

Organic Matter Content ◽

Matter Content ◽

Improved Model

The accurate monitoring of soil water content during the growth of crops is of great importance to improve agricultural water use efficiency. The Campbell model is one of the most widely used models for monitoring soil moisture content from soil thermal conductivities in farmland, which always needs to be calibrated due to the lack of adequate original data and the limitation of measurement methods. To precisely predict the water content of complex soils using the Campbell model, this model was evaluated by investigating several factors, including soil texture, bulk density and organic matter. The comparison of the R2 and the reduced Chi-Sqr values, which were calculated by Origin, was conducted to calibrate the Campbell model calculated. In addition, combining factors of parameters, a new parameter named m related to soil texture and the organic matter was firstly introduced and the original fitting parameter, E, was improved to an expression related to clay fraction and the organic matter content in the improved model. The soil data collected from both the laboratory and the previous literature were used to assess the revised model. The results show that most of the R2 values of the improved model are >0.95, and the reduced Chi-Sqr values are <0.01, which presents a better matching performance compared to the original. It is concluded that the improved model provides more accurate monitoring of soil water content for water irrigation management.

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Soil water potential during different phenological phases of coffee irrigated by center pivot

Engenharia Agrícola ◽

10.1590/s0100-69162013000200006 ◽

2013 ◽

Vol 33 (2) ◽

pp. 269-278 ◽

Cited By ~ 1

Author(s):

Adão W. P. Evangelista ◽

Luiz A. Lima ◽

Antônio C. da Silva ◽

Carla de P. Martins ◽

Moisés S. Ribeiro

Keyword(s):

Water Potential ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Irrigation Management ◽

Soil Water Potential ◽

Field Capacity ◽

Limiting Factor ◽

Center Pivot ◽

Phenological Phases

Irrigation management can be established, considering the soil water potential, as the limiting factor for plant growth, assuming the soil water content between the field capacity and the permanent wilting point as available water for crops. Thus, the aim of this study was to establish the soil water potential interval during four different phenological phases of coffee irrigated by center pivot. The experiment was set at the experimental area of the Engineering Department at the Federal University of Lavras, in Brazil. The coffee variety planted is designated as Rubi, planted 0.8 meters apart, with rows spaced 3.5 meters apart. The treatments corresponded to the water depths applied based on different percentages of Kc and reference evapotranspiration (ET0) values. Sensors were used to measure the soil water potential interval, installed 25 centimeters depth. In order to compare the results, it was considered as the best matric potential the one that was balanced with the soil water content that resulted in the largest coffee productivity. Based on the obtained results, we verified that in the phases of fruit expansion and ripening, the best results were obtained, before the irrigations, when the soil water potential values reached -35 and -38 kPa, respectively. And in the flowering, small green and fruit expansion phases, when the values reached -31 and -32 kPa, respectively.

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ESTIMATES OF SOIL WATER CONTENT USING GROUND-PENETRATING RADAR IN FIELD CONDITIONS

Brazilian Journal of Geophysics ◽

10.22564/rbgf.v33i3.742 ◽

2016 ◽

Vol 33 (3) ◽

Author(s):

Marcelo Jorge Luz Mesquita ◽

José Gouvêa Luiz ◽

José de Paulo Rocha da Costa

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Ground Penetrating Radar ◽

Field Conditions ◽

Electromagnetic Properties ◽

Shallow Subsurface ◽

Electromagnetic Methods ◽

Ground Penetrating

ABSTRACT. Electromagnetic methods play an important role in the study of soil water content, mainly because electromagnetic properties in the shallow subsurface area are primarily controlled by the presence of... RESUMO. Os métodos eletromagnéticos são uma importante ferramenta no estudo da umidade do solo, principalmente porque as propriedades eletromagnéticas da subsuperfície rasa são...

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Calibration and evaluation of a capacitance probe in agricultural soils in northeast Brazil

10.5194/egusphere-egu2020-5774 ◽

2020 ◽

Author(s):

Ceres Duarte Guedes Cabral de Almeida ◽

Lais Barreto Franco ◽

José Ediclécio Barbosa dos Santos ◽

Brivaldo Gomes de Almeida ◽

Giuseppe Provenzano

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Agricultural Soils ◽

Irrigation Management ◽

Clay Loam ◽

Sandy Clay Loam ◽

Sandy Clay ◽

Disturbed Soil ◽

Capacitance Probe

Soil water content is an important parameter for irrigation management. Among the indirect methods to determine soil water content (SWC), there are electronic sensors, that need site-specific calibration to increase the accuracy of the measurements. In this research, a capacitance probe (Diviner 2000&#174;, Sentek Pty Ltda., Australia) was calibrated for two agricultural soils. The experiment was carried out in a protected environment at the Federal Rural University of Pernambuco (UFRPE), Brazil. The textural classes of soils were sandy clay loam (66% sand) and sandy (95% sand). Undisturbed and disturbed soil samples were collected in the soil top layer (0-30 cm). The disturbed soil samples were initially air-dried, passed through a 4.75 mm mesh sieve, and then introduced to fill eight vessels (four replications for each soil). These vessels, equipped with drainage holes, have lower and upper diameters of 15 cm and 25 cm, respectively, and height of 22.5 cm (4.66 L). In each pot, a 5 cm layer of gravel with an average diameter of 2 cm covered with bidim&#174; geotextile was disposed before introducing the soil. During filling, the soil was compacted to reach the same bulk density measured on the undisturbed samples (sandy clay loam: 1.54 g cm-3 and sandy: 1.50 g cm-3). In the center of each pot, a PVC access tube was installed. According to the manufacturer's recommendation, during calibration, the probe normalization was performed. The pots were wetted by capillary rise and, once saturated, they were placed on a bench for drainage. After this process stopped each pot was daily weighed at a fixed time (8 a.m.), and the sensor reading was acquired until when the daily mass variations became negligible. Data were used for regression analysis to fit the site-specific calibration equation and to evaluate the mean error. Linear calibration equations, characterized by R2=0.931 and 0.986, were obtained for the sandy clay loam and the sandy soil, respectively. The mean errors (ME) associated with the manufacturer&#8217;s equation resulted in -0.05 and -0.01 for sandy clay loam and for sandy soil and decreased after calibration. The results confirmed the suitability of the manufacturer's equation in sandy soils. On the other hand, the manufacture&#8217;s equation slightly underestimated SWC, in sandy clay loam soil, especially in the range above 0.26 m3 m-3. The Diviner 2000 probe can be therefore successfully used to support irrigation management in irrigated areas with soils similar to those investigated because it is easy to operate and allows fairly accurate estimations of soil water content.

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Evaluation of Soil Water Content Measurements with Capacitance Probes to Support Irrigation Scheduling in a “Red Beaut” Japanese Plum Orchard

Agronomy ◽

10.3390/agronomy10111757 ◽

2020 ◽

Vol 10 (11) ◽

pp. 1757

Author(s):

Sandra Millán ◽

Carlos Campillo ◽

Antonio Vivas ◽

María José Moñino ◽

Maria Henar Prieto

Keyword(s):

Soil Moisture ◽

Water Stress ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Irrigation Management ◽

Irrigation Scheduling ◽

Successful Implementation ◽

Stem Water Potential ◽

Japanese Plum

Advances in electromagnetic sensor technologies in recent years have made automated irrigation scheduling a reality through the use of state-of-the-art soil moisture sensing devices. However, correct sensor positioning and interpretation of the measurements are key to the successful implementation of these management systems. The aim of this study is to establish guidelines for soil moisture sensor placement to support irrigation scheduling, taking into account the physiological response of the plant. The experimental work was carried out in Vegas Bajas del Guadiana (Extremadura, Spain) on a drip-irrigated experimental orchard of the early-maturing Japanese plum cultivar “Red Beaut”. Two irrigation treatments were established: control and drying. The control treatment was scheduled to cover crop water needs. In the drying treatment, the fruit trees were irrigated as in control, except in certain periods (preharvest and postharvest) in which irrigation was suspended (drying cycles). Over 3 years (2015–2017), a series of plant parameters were analyzed in relation to the measurements provided by a battery of frequency domain reflectometry probes installed in different positions with respect to tree and dripper: midday stem water potential (Ψstem), sap flow, leaf stomatal conductance, net leaf photosynthesis and daily fraction of intercepted photosynthetically active radiation. After making a comparison of these measurements as indicators of plant water status, Ψstem was found to be the physiological parameter that detected water stress earliest. The drying cycles were very useful to select the probe positions that provided the best information for irrigation management and to establish a threshold in the different phases of the crop below which detrimental effects could be caused to the crop. With respect to the probes located closest to the drippers, a drop in the relative soil water content (RSWC) below 0.2 would not be advisable for “non-stress” scheduling in the preharvest period. When no deficit irrigation strategies are applied in the postharvest period, the criteria are similar to those of preharvest. However, the probes located between the dripper at 0.15 and 0.30 m depth provide information on moderate water stress if the RSWC values falls below 0.2. The severe tree water stress was detected below 0.1 RSWC in probes located at 60 cm depth from this same position.

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Effect of Initial Soil Water Content on Output Parameters of Sirmod Software Under Types of Different Irrigation Management

Irrigation and Drainage ◽

10.1002/ird.2371 ◽

2019 ◽

Vol 68 (4) ◽

pp. 740-752

Author(s):

Ali Javadi ◽

Behrouz Mostafazadeh‐Fard ◽

Mohammad Shayannejad ◽

Hamed Ebrahimian

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Irrigation Management ◽

Initial Soil

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The Effect of Soil Iron on the Estimation of Soil Water Content Using Dielectric Sensors

Water ◽

10.3390/w12020598 ◽

2020 ◽

Vol 12 (2) ◽

pp. 598

Author(s):

George Kargas ◽

Paraskevi Londra ◽

Marianthi Anastasatou ◽

Nick Moustakas

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Iron Content ◽

Sandy Loam ◽

High Iron Content ◽

Volumetric Soil Water Content ◽

High Iron ◽

The Difference ◽

Dielectric Sensors

Nowadays, the estimation of volumetric soil water content (θ) through apparent dielectric permittivity (εa) is the most widely used method. The purpose of this study is to investigate the effect of the high iron content of two sandy loam soils on estimating their water content using two dielectric sensors. These sensors are the WET sensor operating at 20 MHz and the ML2 sensor operating at 100 MHz. Experiments on specific soil columns, in the laboratory, by mixing different amounts of water in the soils to obtain a range of θ values under constant temperature conditions were conducted. Analysis of the results showed that both sensors, based on manufacturer calibration, led to overestimation of θ. This overestimation is due to the high measured values of εa by both sensors used. The WET sensor, operating at a lower frequency and being strongly affected by soil characteristics, showed the greatest overestimation. The difference of εa values between the two sensors ranged from 14 to 19 units at the maximum actual soil water content (θm). Compared to the Topp equation, the WET sensor measures 2.3 to 2.8 fold higher value of εa. From the results, it was shown that the relationship θm-εa0.5 remained linear even in the case of these soils with high iron content and the multi-point calibration (CALALL) is a good option where individual calibration is needed.

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