Irrigation controlled by a wetting front detector: field evaluation under sprinkler irrigation

Soil Research ◽  
2005 ◽  
Vol 43 (8) ◽  
pp. 935 ◽  
Author(s):  
R. J. Stirzaker ◽  
P. A. Hutchinson
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Unsaturated Flow ◽  
Free Water ◽  
Sprinkler Irrigation ◽  
Field Evaluation ◽  
Wetting Front ◽  
Irrigation Amount ◽  
Irrigation Interval

The accuracy of scheduling irrigation to turf by sprinkler was evaluated using a simple wetting front detector that automatically switched the water off after the wetting front had reached a prescribed depth in the soil. The detector consists of a funnel-shaped container that is buried in the soil. When a wetting front reaches the detector, the unsaturated flow lines are distorted so that the water content at the base of the funnel reaches saturation. The free water produced is detected electronically and this provides the signal to stop irrigation. The performance of the detector was evaluated over 38 consecutive irrigation events to test the theory that the velocity of a wetting front depends on the difference in water content ahead of and behind the front. The experimental data plotting the irrigation amount permitted by the wetting front detectors as a function of the soil water content before and after irrigation yielded a linear relationship with a slope of 0.95 and a correlation coefficient of 0.73. Thus, if the soil is dry before irrigation the front will move slowly and an irrigation of long duration will be permitted, with the converse applying to wet soil. Independent monitoring of soil water content showed that irrigation was, for the most part, scheduled accurately. Irrigation interval was the key variable to control. When the interval was too short then over irrigation occurred.

scholarly journals Estimating Soil Water Content and Evapotranspiration of Winter Wheat under Deficit Irrigation Based on SWAP Model

2020 ◽  
Vol 12 (22) ◽  
pp. 9451
Author(s):  
Xiaowen Wang ◽  
Huanjie Cai ◽  
Liang Li ◽  
Xiaoyun Wang
Keyword(s):  
Winter Wheat ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Deficit Irrigation ◽  
Irrigation Treatment ◽  
Water Dynamics ◽  
Growth Stages ◽  
Irrigation Amount ◽  
Swap Model

Deficit irrigation strategy is essential for sustainable agricultural development in arid regions. A two−year deficit irrigation field experiment was conducted to study the water dynamics of winter wheat under deficit irrigation in Guanzhong Plain in Northwest China. Three irrigation levels were implemented during four growth stages of winter wheat: 100%, 80% and 60% of actual evapotranspiration (ET) measured by the lysimeter with sufficient irrigation treatment (CK). The agro−hydrological model soil−water−atmosphere−plant (SWAP) was used to simulate the components of the farmland water budget. Sensitivity analysis for parameters of SWAP indicated that the saturated water content and water content shape factor n were more sensitive than the other parameters. The verification results showed that the SWAP model accurately simulated soil water content (average relative error (MRE) < 21.66%, root mean square error (RMSE) < 0.07 cm3 cm−3) and ET (R2 = 0.975, p < 0.01). Irrigation had an important impact on actual plant transpiration, but the actual soil evaporation had little change among different treatments. The average deep percolation was 14.54 mm and positively correlated with the total irrigation amount. The model established using path analysis and regression methods for estimating ET performed well (R2 = 0.727, p < 0.01). This study provided effective guidance for SWAP model parameter calibration and a convenient way to accurately estimate ET with fewer variables.

Laboratory and field evaluation of five soil water sensors

2004 ◽  
Vol 84 (4) ◽  
pp. 431-438 ◽  
Author(s):  
Q. Huang ◽  
O. O. Akinremi ◽  
R. Sri Rajan ◽  
P. Bullock
Keyword(s):  
Water Content ◽  
Bulk Density ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Field Evaluation ◽  
Soil Bulk Density ◽  
Laboratory Evaluation ◽  
Engineering Sciences ◽  
Probe Calibration

Accurate in situ determination of soil water content is important in many fields of agricultural, environmental, hydrological, and engineering sciences. As numerous soil water content sensors are available on the market today, the knowledge of their performance will aid users in the selection of appropriate sensors. The objectives of this study were to evaluate five soil water sensors in the laboratory and to determine if laboratory calibration is appropriate for the field. In this study, the performances of five sensors, including the Profile Probe™ (PP), ThetaProbe™ , Watermark™, Aqua-Tel™, and Aquaterr™ were compared in the laboratory. The PP and ThetaProbe™ were more accurate than the other soil water sensors, reproducing soil water content using factory recommended parameters. However, when PP was installed on a loamy sand in the field, the same soil that was used for the laboratory evaluation, it overestimated field soil water, especially at depth. Another laboratory experiment showed that soil water content readings from the PP were strongly influenced by soil bulk density. The higher the soil bulk density, the greater was the overestimation of soil water content. Two regression parameters, a0 and a1, which are used to convert the apparent dielectric constant to volumetric water content, were found to increase linearly with the soil bulk density in the range of 1.2 to 1.6 Mg m-3. Finally, the PP was calibrated in the field and a good calibration function was obtained with an r2 of 0.87 and RMSE of 2.7%. The values of a0 and a1 obtained in the field were different from factory recommended parameters (a0 = 2.4 versus 1.6 while a1 = 12.5 versus 8.4) and were independent of soil depth, bulk density, and texture. As such, individual field calibration will be necessary to obtain precise and accurate measurement of soil water content with this instrument. Key words: Soil water content, Profile Probe, calibration, soil water content sensor

scholarly journals Soil water-balance-based approach for estimating percolation with lysimeter and in field with and without mulch under micro irrigation

2021 ◽  
Vol 16 (5) ◽  
pp. 1-12
Author(s):  
Eugênio Ferreira Coelho ◽  
Marcos de Souza Campos ◽  
Marcelo Rocha dos Santos ◽  
Rafael Dreux Miranda Fernandes ◽  
Jailson Lopes Cruz
Keyword(s):  
Water Balance ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Zone ◽  
Sprinkler Irrigation ◽  
Time Domain Reflectometry ◽  
Soil Water Balance ◽  
Time Intervals ◽  
Reliable Determination

Precise, accurate knowledge of percolation is key to reliable determination of soil water balance and a crop’s water-use efficiency. This work evaluated an approach to estimate the amount of water percolated in the root zone using soil water content (SWC) data measured at different time intervals. The approach was based on the difference of soil water content within and below the effective root zone of banana plants at different time intervals. A drainage lysimeter was used to compare the measured and estimated percolation data. The approach was then used in a banana orchard under drip and micro sprinkler irrigation, with and without the use of mulch. The soil water storage in the banana’s root zone was evaluated within a two-dimensional soil profile with time domain reflectometry (TDR). Mean percolation measured in the lysimeters did not differ from the approach’s estimates using intervals between SWC readings equal to or longer than 6 h from the end of an irrigation event. Percolation estimates under drip and micro sprinkler irrigation in the field, with and without mulch, were consistent with those measured in the lysimeters, considering the 6-h interval of SWC measurements. Percolation was greater under the drip irrigation system with mulch. The amount of water percolated was not influenced by the presence of mulch under the micro sprinkler system. Keywords: localized irrigation, soil water balance, soil water content sensor.

Field Evaluation of the Dual-Probe Heat-Pulse Method for Measuring Soil Water Content

2003 ◽  
Vol 2 (4) ◽  
pp. 552 ◽  
Author(s):  
J. L. Heitman ◽  
J. M. Basinger ◽  
G. J. Kluitenberg ◽  
J. M. Ham ◽  
J. M. Frank ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Evaluation ◽  
Pulse Method ◽  
Heat Pulse ◽  
Dual Probe

scholarly journals Study on the Response of Different Soybean Varieties to Water Management in Northwest China Based on a Model Approach

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 824
Author(s):  
Yunxuan Zhang ◽  
Sien Li ◽  
Mousong Wu ◽  
Danni Yang ◽  
Chunyu Wang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Experiments ◽  
Economic Value ◽  
Maximum Yield ◽  
Northwest China ◽  
Irrigation Amount ◽  
Water Treatments ◽  
Soil Moisture Status

Soybean is one of the major crops that is widely cultivated in Northwest China due to its high nutritional and economic value. However, drought has recently become an important factor restricting the growth of soybeans in the arid region of Northwest China and the selection of drought-resistant soybean is of importance for cooperating with drought and improving yield. In this study, three-year soybean field experiments were conducted to test the effects of different water treatments on the soil moisture status and the yield of two varieties of soybeans (Longhuang1 (LH1), Longahuang3 (LH3)). Based on the field data, the soil water content, biomass, LAI, and yield were calibrated and evaluated using the soil-crop system model WHCNS (soil Water Heat Carbon Nitrogen Simulator). The results showed that the nRMSE, NSE, IA, and R2 of the soil water content from two types of soybean, i.e., LH1 (LH3) were 10.98% (9.79%), 0.86 (0.90), 0.96 (0.97), 0.87 (0.90), respectively. The nRMSE, NSE, IA and R2 of the yield of LH1 (LH3) were 19.12% (4.41%), 0.87 (0.99), 0.97 (1.00), 0.98 (0.99), respectively. Scenario simulations of yield and other indicators in two soybean varieties under different irrigation schedules in different hydrological years showed that the maximum yield and II of LH3 are lower than those of LH1, but the higher yield and II of LH1 comes from a larger irrigation amount. Appropriately reducing the number of irrigations in the branching period will not reduce crop yield and may oppositely lead to a small increase in yield and income; reducing the number of irrigations at the end of grouting has no significant impact on yield and income.

scholarly journals Wetting Body Characteristics and Infiltration Model of Film Hole Irrigation

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1226
Author(s):  
Fei-long Jie ◽  
Liang-jun Fei ◽  
Yun Zhong ◽  
Li-hua Liu ◽  
Shou-xuan Kang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Geometric Mean ◽  
Silt Loam ◽  
Wetting Front ◽  
Equivalent Radius ◽  
Volume Model ◽  
Cumulative Infiltration ◽  
Irrigation Volume

Film hole irrigation is a relatively low cost and high efficiency irrigation method, which can significantly improve the efficiency of agricultural water use. In order to establish the quantitative model of film hole irrigation between cumulative infiltration and the wetting body and the irrigation volume model of crops, the infiltration process and wetting body characteristics of four different soils (Xi’an silt loam, silt, silt loam and loam) were studied in laboratory experiments and numerical HYDRUS simulation experiments. The relationship between cumulative infiltration and wetting body radius was established using a mathematical method, and a crop irrigation volume model was proposed based on the root distribution and the required water content of different crops. The experimental results showed that the shape of the wetting body of film hole irrigation is approximately half of the rotating ellipsoid, and the curve shape of the wetting front can be expressed using an elliptic equation. From the center of the film hole to the surface of the wetting front, the soil water content of the wetting body gradually decreases, and the change rate of water content gradually increases, reaching its maximum value near the wetting front. Furthermore, the distribution of water content in the wetting body can be accurately expressed using an elliptic curve equation. The cumulative infiltration of film hole irrigation is proportional to the third power of the equivalent radius of the wetting body, and the equivalent radius is equal to the geometric mean of the horizontal and vertical migration distances of the wetting front. In addition, based on the distribution of crop roots and the demand of crop roots on soil water content, the irrigation model of crops was established. This study provides a theoretical basis for the calculation of the irrigation volume for film hole irrigation under the condition of experiment, and has a guiding significance for the field experiment and application of film hole irrigation in different crops in future.

scholarly journals Field evaluation of portable soil water content sensors in a sandy loam

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Hyunglok Kim ◽  
Michael H. Cosh ◽  
Rajat Bindlish ◽  
Venkataraman Lakshmi
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Sandy Loam ◽  
Field Evaluation

scholarly journals Field Evaluation of the Dual-Probe Heat-Pulse Method for Measuring Soil Water Content

2003 ◽  
Vol 2 (4) ◽  
pp. 552-560 ◽  
Author(s):  
J. L. Heitman ◽  
J. M. Basinger ◽  
G. J. Kluitenberg ◽  
J. M. Ham ◽  
J. M. Frank ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Field Evaluation ◽  
Pulse Method ◽  
Heat Pulse ◽  
Dual Probe
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