Wetting Body Characteristics and Infiltration Model of Film Hole Irrigation

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.

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Effects of Soil Water Content on Oxadiazon Dissipation

Weed Science ◽

10.1017/s0043174500059816 ◽

1984 ◽

Vol 32 (5) ◽

pp. 697-701 ◽

Cited By ~ 11

Author(s):

Michael R. Barrett ◽

Terry L. Lavy

Keyword(s):

Oryza Sativa ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Laboratory Study ◽

Management Systems ◽

Silt Loam

In a Crowley silt loam, between 30 kPa, continuous flood, and alternate flood laboratory treatments at 25 C, dissipation of incorporated oxadiazon [2-tert-butyl-4(2,4-dichloro-5-isopropoxyphenyl)-Δ2-1,3,4-oxadiazolin-5-one] varied little, with an average of 59% remaining after 20 weeks. In the greenhouse, subsurface application of oxadiazon reduced its phytotoxicity but increased its persistence up to four times more than with surface-applied oxadiazon. In the field, 50% of the surface-applied oxadiazon dissipated from the soil within 6 to 11 days when the soil was flush irrigated and then flooded, compared to 15 to 17 days when the soil was irrigated but not flooded in two rice (Oryza sativaL.) management systems. Oxadiazon dissipation in the field was greater during the first 2 or 3 weeks after application than in the laboratory study. This is explained at least partially by the lack of herbicide incorporation in the field.

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Water mass balance in the case of vertical infiltration

Global NEST Journal ◽

10.30955/gnj.000364 ◽

2013 ◽

Vol 7 (3) ◽

pp. 274-280

Keyword(s):

Water Content ◽

Soil Water ◽

Algebraic Model ◽

Water Infiltration ◽

Wetting Front ◽

Retention Curve ◽

Soil Water Infiltration ◽

Cumulative Infiltration ◽

Richard's Equation ◽

Water Mass Balance

Water movement in the unsaturated zone is an important hydrological process. Richard’s equation is windily used to describe both soil water infiltration and soil water absorption. Various methods have been developed to solve Richard’s equation. Wang et al. (2003) have developed an algebraic model for the description of soil water infiltration, based on Parlange’s solution of Richard’s equation and on soil retention curve and hydraulic conductivity equation given by Brooks and Corey. Their model utilizes experimental measurements of the cumulative infiltration volume and the wetting front distance as functions of time in order to describe soil water infiltration. The objective of this paper is to test the accuracy of the Wang et al. algebraic model for the one-dimensional (vertical) soil water infiltration. A vertical infiltration experiment was conducted on a sandy soil, for the measurement of the cumulative infiltration volume and the wetting front distance. Soil water content was determined at selected times and positions, using gamma ray absorption. Additionally the hydraulic conductivity K(θ) and the soil retention curve Ψ(θ) were determined. The algebraic model developed by Wang et al., was found simple to use since the required data are the cumulative infiltration (F), the wetting front distance (zf) and the initial and saturated soil water content (θi and θs respectively). The results show a fair agreement between calculated and measured values on soil water content profiles, hydraulic conductivity and on the water mass balance.

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Effect of variability in soil properties plus model complexity on predicting topsoil water content and nitrous oxide emissions

Soil Research ◽

10.1071/sr18080 ◽

2018 ◽

Vol 56 (8) ◽

pp. 810 ◽

Cited By ~ 2

Author(s):

Iris Vogeler ◽

Rogerio Cichota

Keyword(s):

Nitrous Oxide ◽

Soil Properties ◽

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Profile ◽

Nitrous Oxide Emissions ◽

Soil Types ◽

N2o Emissions ◽

Silt Loam

Despite the importance of soil physical properties on water infiltration and redistribution, little is known about the effect of variability in soil properties and its consequent effect on contaminant loss pathways. To investigate the effects of uncertainty and heterogeneity in measured soil physical parameters on the simulated movement of water and the prediction of nitrous oxide (N2O) emissions, we set up the Agricultural Production Systems sIMulator (APSIM) for different soil types in three different regions of New Zealand: the Te Kowhai silt loam and the Horotiu silt loam in the Waikato region, and the Templeton silt loam in the Canterbury region, and the Otokia silt loam and the Wingatui silt loam in the Otago region. For each of the soil types, various measured soil profile descriptions, as well as those from a national soils database (S-map) were used when available. In addition, three different soil water models in APSIM with different complexities (SWIM2, SWIM3, and SoilWat) were evaluated. Model outputs were compared with temporal soil water content measurements within the top 75mm at the various experimental sites. Results show that the profile description, as well as the soil water model used affected the prediction accuracy of soil water content. The smallest difference between soil profile descriptions was found for the Templeton soil series, where the model efficiency (NSE) was positive for all soil profile descriptions, and the RMSE ranged from 0.055 to 0.069m3/m3. The greatest difference was found for the Te Kowhai soil, where only one of the descriptions showed a positive NSE, and the other two profile descriptions overestimated measured topsoil water contents. Furthermore, it was shown that the soil profile description highly affects N2O emissions from urinary N deposited during animal grazing. However, the relative difference between the emissions was not always related to the accuracy of the measured soil water content, with soil organic carbon content also affecting emissions.

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Soil water content dependent wetting front characteristics in sands

Journal of Hydrology ◽

10.1016/s0022-1694(00)00198-0 ◽

2000 ◽

Vol 231-232 ◽

pp. 244-254 ◽

Cited By ~ 68

Author(s):

T.W.J Bauters ◽

D.A DiCarlo ◽

T.S Steenhuis ◽

J.-Y Parlange

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Wetting Front

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

Soil Research ◽

10.1071/sr05005 ◽

2005 ◽

Vol 43 (8) ◽

pp. 935 ◽

Cited By ~ 14

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.

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SOIL WATER CONTENT AFFECTS THE AVAILABILITY OF PHOSPHATE

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1985.46.1696 ◽

1985 ◽

pp. 185-189

Author(s):

M.C.H.Mouat Pieter Nes

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Soil Solution ◽

Equivalent Reduction

Reduction in water content of a soil increased the concentration of ammonium and nitrate in solution, but had no effect on the concentration of phosphate. The corresponding reduction in the quantity of phosphate in solution caused an equivalent reduction in the response of ryegrass to applied phosphate. Keywords: soil solution, soil water content, phosphate, ryegrass, nutrition.

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Effect of inter-row cultivation on soil carbon dioxide emission in a peach plantation

Agrokémia és Talajtan ◽

10.1556/agrokem.59.2010.1.19 ◽

2010 ◽

Vol 59 (1) ◽

pp. 157-164 ◽

Cited By ~ 1

Author(s):

E. Tóth ◽

Cs. Farkas

Keyword(s):

Water Content ◽

Soil Water ◽

Soil Water Content ◽

Carbon Dioxide Emission ◽

Nutrient Content ◽

Soil Disturbance ◽

Biological Properties ◽

Soil Tillage ◽

Favourable Effect ◽

Volumetric Soil Water Content

Soil biological properties and CO2emission were compared in undisturbed grass and regularly disked rows of a peach plantation. Higher nutrient content and biological activity were found in the undisturbed, grass-covered rows. Significantly higher CO2fluxes were measured in this treatment at almost all the measurement times, in all the soil water content ranges, except the one in which the volumetric soil water content was higher than 45%. The obtained results indicated that in addition to the favourable effect of soil tillage on soil aeration, regular soil disturbance reduces soil microbial activity and soil CO2emission.

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