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

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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Numerical Modeling of Water Movement from Buried Vertical Ceramic Pipes through Soils

Journal of Engineering ◽

10.31026/j.eng.2018.06.06 ◽

2018 ◽

Vol 24 (6) ◽

pp. 72

Author(s):

Zena Kamil Rasheed ◽

Maysoon Basheer Abid

Keyword(s):

Hydraulic Conductivity ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Transient Flow ◽

Initial Conditions ◽

Irrigation System ◽

Pipe Length ◽

Ceramic Pipe ◽

Initial Soil

The problem of water scarcity is becoming common in many parts of the world, to overcome part of this problem proper management of water and an efficient irrigation system are needed. Irrigation with a buried vertical ceramic pipe is known as a very effective in the management of irrigation water. The two- dimensional transient flow of water from a buried vertical ceramic pipe through homogenous porous media is simulated numerically using the HYDRUS/2D software. Different values of pipe lengths and hydraulic conductivity were selected. In addition, different values of initial volumetric soil water content were assumed in this simulation as initial conditions. Different values of the applied head were assumed in this simulation as boundary conditions. The results of this research showed that greater spreading occurs in the horizontal direction. Increasing applied heads, initial soil water contents and pipe hydraulic conductivities, cause increasing the size of wetting patterns but in a few increases. Also, the results showed that the empirical formulas which can be used for expressing the wetted width and depth in terms of applied head, initial soil water content, application time, pipe hydraulic conductivity, and pipe length, are good and can be used as design equations.

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Numerical Modeling of Water Movement from Buried Vertical Ceramic Pipes through Coarse Soils

Al-Khwarizmi Engineering Journal ◽

10.22153/kej.2017.06.003 ◽

2018 ◽

Vol 13 (4) ◽

pp. 164-173

Author(s):

Zena Kamil Rasheed ◽

Maysoon Basheer Abid

Keyword(s):

Hydraulic Conductivity ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Transient Flow ◽

Vertical Direction ◽

Empirical Formulas ◽

Pipe Length ◽

Ceramic Pipe ◽

Initial Soil

Problem of water scarcity is becoming common in many parts of the world. Thus to overcome this problem proper management of water and an efficient irrigation systems are needed. Irrigation with buried vertical ceramic pipe is known as a very effective in management of irrigation water. The two- dimensional transient flow of water from a buried vertical ceramic pipe through homogenous porous media is simulated numerically using the software HYDRUS/2D to predict empirical formulas that describe the predicted results accurately. Different values of pipe lengths and hydraulic conductivity were selected. In addition, different values of initial volumetric soil water content were assumed in this simulation as initial conditions. Different values of applied head were assumed in this simulation as a boundary conditions. In general, a good agreement was obtained when comparing the predicted results with available measured values. The results of this research showed that greater spreading occur in vertical direction. Increasing applied heads, initial soil water contents, pipe hydraulic conductivities, cause increasing the size of wetting patterns. Also the results showed that the empirical formulas which can be used for expressing the wetted width and depth in terms of applied head, initial soil water content, application time, pipe hydraulic conductivity, and pipe length, are good and can be used as a designing equations.

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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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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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