Editorial

3 pages, 182 KiB

Open AccessEditorial

Study of the Soil Water Movement in Irrigated Agriculture Ⅱ

by George Kargas, Petros Kerkides and Paraskevi A. Londra

Water 2023, 15(11), 2033; https://doi.org/10.3390/w15112033 - 27 May 2023

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This Special Issue of Water is the second part of the series “Study of Soil Water Movement in Irrigated Agriculture” [...] Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

Research

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17 pages, 4562 KiB

Open AccessArticle

Experimental Investigations on Influence of Fracture Networks on Overland Flow and Water Infiltration in Soil

by Jin You, Shuqian Wang and Dan Xu

Water 2022, 14(21), 3483; https://doi.org/10.3390/w14213483 - 31 Oct 2022

Cited by 2 | Viewed by 1627

Abstract

Soil preferential flow is an essential process that affects the movement and relocation of soil water and solutes. This study was conducted on cropland in an arid and semi-arid area in Zhongning County, Ningxia. According to the different cracks, rain intensity, rainfall duration, [...] Read more.

Soil preferential flow is an essential process that affects the movement and relocation of soil water and solutes. This study was conducted on cropland in an arid and semi-arid area in Zhongning County, Ningxia. According to the different cracks, rain intensity, rainfall duration, and slope, there were three groups, and 17 dye tracer experiments were conducted in the field. We quantified the characteristics of soil preferential flow by investigating and analyzing the infiltration depth, dyeing area, saturation, runoff coefficient, and rainfall infiltration coefficient using the dye tracer method. The results showed that increasing the rainfall or irrigation intensity could promote the activation of the fracture channel as the preferential flow channel, which is advantageous to the preferential flow formation. The fractures dominated the formation of the preferential flow. The fractures slowed the formation of runoff, reduced the velocity of slope flow, reduced the flow of the slope, and increased the amount of soil water infiltration. These results have theoretical and practical significance for understanding soil water transportation, especially for agricultural irrigation management and improving cropland water use efficiency in arid and semi-arid areas. Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

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13 pages, 1604 KiB

Open AccessArticle

Hydrodynamic Border Irrigation Model: Comparison of Infiltration Equations

by Sebastián Fuentes, Carlos Chávez, Fernando Brambila-Paz and Josué Trejo-Alonso

Water 2022, 14(13), 2111; https://doi.org/10.3390/w14132111 - 01 Jul 2022

Cited by 1 | Viewed by 1545

Abstract

The variation in moisture content between subsequent irrigations determines the use of infiltration equations that contain representative physical parameters of the soil when irrigation begins. This study analyzes the reliability of the hydrodynamic model to simulate the advanced phase in border irrigation. For [...] Read more.

The variation in moisture content between subsequent irrigations determines the use of infiltration equations that contain representative physical parameters of the soil when irrigation begins. This study analyzes the reliability of the hydrodynamic model to simulate the advanced phase in border irrigation. For the solution of the hydrodynamic model, a Lagrangian scheme in implicit finite differences is used, while for infiltration, the Kostiakov equation and the Green and Ampt equation are used and compared. The latter was solved using the Newton–Raphson method due to its implicit nature. The models were validated, and unknown parameters were optimized using experimental data available in the literature and the Levenberg–Marquardt method. The results show that it is necessary to use infiltration equations based on soil parameters, because in subsequent irrigations, the initial conditions change, modifying the advance curve in border irrigation. From the coupling of both equations, it is shown that the empirical Kostiakov equation is only representative for a specific irrigation event, while with the Green and Ampt equations, the subsequent irrigations can be modeled, and the advance/infiltration process can be observed in detail. Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

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16 pages, 3987 KiB

Open AccessArticle

A Comprehensive Model for Hydraulic Analysis and Wetting Patterns Simulation under Subsurface Drip Laterals

by Saeid Zamani, Rouhollah Fatahi and Giuseppe Provenzano

Water 2022, 14(12), 1965; https://doi.org/10.3390/w14121965 - 19 Jun 2022

Cited by 2 | Viewed by 2161

Abstract

In the absence of suitable specialized models to simulate the soil wetting patterns in subsurface drip irrigation systems considering the hydraulic conditions along the laterals, a new model was developed and named a “comprehensive model” in this study. This model couples the subsurface [...] Read more.

In the absence of suitable specialized models to simulate the soil wetting patterns in subsurface drip irrigation systems considering the hydraulic conditions along the laterals, a new model was developed and named a “comprehensive model” in this study. This model couples the subsurface drip irrigation lateral characteristics with the soil hydraulic properties and utilizes the Hydrus-3D software as a complementary section of the model to simulate the wetting front beneath the lateral. To evaluate the model, three 16 mm drip-line pipes of 62 m length with 20, 40, and 50 cm spacing emitters and 2 to 5 L/h discharge were buried at 0.2 m depth in a soil box containing clay loamy soil. Then, the experiments were conducted at 50, 100, and 150 kPa pressures, and the wetting pattern geometry associated with each lateral was measured at 1, 2, 3, and 24 h and compared with the model simulations. Moreover, the values of the root mean square error (RMSE), mean absolute error (MAE), and the refined index of agreement of the wetting depth beneath the lateral ranged from 0.013 to 0.03 m, 0.002 to 0.004 m, and 0.886 to 0.927 m, respectively. In addition, the mentioned indexes values at the first and the last cross-sections of the laterals varied between 0.001 and 0.004 m, 0.011 and 0.035 m, 0.814 and 0.942 m, respectively. These results proved that the differences between measured and predicted dimensions of the wetting pattern are not significant and comprehensive model provides good estimations of the emitter flow rates, as well as realistic wetting patterns. Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

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10 pages, 2034 KiB

Open AccessArticle

The Effect of Soil Texture on the Conversion Factor of 1:5 Soil/Water Extract Electrical Conductivity (EC_1:5) to Soil Saturated Paste Extract Electrical Conductivity (EC_e)

by George Kargas, Paraskevi Londra and Kyriaki Sotirakoglou

Water 2022, 14(4), 642; https://doi.org/10.3390/w14040642 - 18 Feb 2022

Cited by 7 | Viewed by 2796

Abstract

The electrical conductivity of soil saturated paste extract (EC_e) is used as an indicator for estimating soil salinity. This method is time consuming and laborious and therefore, easier and faster methods are usually used with different soil/water ratios, such as [...] Read more.

The electrical conductivity of soil saturated paste extract (EC_e) is used as an indicator for estimating soil salinity. This method is time consuming and laborious and therefore, easier and faster methods are usually used with different soil/water ratios, such as 1:5 (EC_1:5), for estimating the EC_e. Usually, the relationship between EC_e and EC_1:5 is described by a simple linear empirical equation. The value of the conversion factor (CF) of EC_1:5 to EC_e is affected by the particular characteristics of the soil, such as its texture. The objective of this study is to investigate models that allow the inclusion of soil texture in the calculation of the CF, in order to improve the prediction of the EC_e. A total of 148 soil samples with different soil texture and salinity levels were selected from three regions of Greece, and EC_e, EC_1:5, as well as clay and sand contents were determined. The results show that the CF can be estimated from an equation which incorporates the clay and sand contents through the soil saturation percentage (SP) and can give a fairly good prediction of EC_e from EC_1:5 (R² = 0.9887 and RMSE = 1.39 dSm⁻¹). Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

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12 pages, 2475 KiB

Open AccessArticle

Infiltration under Ponded Conditions

by Ioannis Argyrokastritis, Maria Psychogiou and Paraskevi A. Londra

Water 2021, 13(24), 3492; https://doi.org/10.3390/w13243492 - 07 Dec 2021

Cited by 3 | Viewed by 2119

Abstract

Ponded infiltration processes occur in agricultural lands irrigated by flooding of their soil surface or under insufficient drainage conditions. The existing equations describing the phenomenon of vertical infiltration under ponded conditions have not considered the actual contribution of the pressure head gradient to [...] Read more.

Ponded infiltration processes occur in agricultural lands irrigated by flooding of their soil surface or under insufficient drainage conditions. The existing equations describing the phenomenon of vertical infiltration under ponded conditions have not considered the actual contribution of the pressure head gradient to the flow. In this study, simple equations are proposed to describe the horizontal and vertical infiltration under various ponding heads incorporating the actual contribution of the pressure head gradient to the flow. Six soils with known hydraulic properties, covering a wide range of soil textures, were used. Horizontal and vertical infiltration data are obtained by numerical simulation for all soils studied using the Hydrus-1D code. To validate the accuracy of the proposed equations, the solutions of horizontal and vertical infiltrations provided by the proposed equations were compared with numerically simulated ones provided by the Hydrus 1-D. The analysis of the results showed a very good agreement in all soils studied. The proposed vertical infiltration equation was also compared to a simple and accurate equation which does not incorporate the actual contribution of the pressure head gradient to the flow and differences between them were observed in all soils studied. Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

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13 pages, 3273 KiB

Open AccessArticle

Effects of Drying-Rewetting Cycles on Ferrous Iron-Involved Denitrification in Paddy Soils

by Yushuai Zhang, Baokun Xu, Jiangpei Han and Liangsheng Shi

Water 2021, 13(22), 3212; https://doi.org/10.3390/w13223212 - 12 Nov 2021

Cited by 5 | Viewed by 1976

Abstract

Soil moisture status has an important effect on the process of denitrification in paddy soils. However, it is unclear how it affects the ferrous iron-involved denitrification. Here, the influence of drying-rewetting cycles on ferrous iron-involved denitrification in paddy soil were studied with batch [...] Read more.

Soil moisture status has an important effect on the process of denitrification in paddy soils. However, it is unclear how it affects the ferrous iron-involved denitrification. Here, the influence of drying-rewetting cycles on ferrous iron-involved denitrification in paddy soil were studied with batch experiments. The dynamics of nitrate, ammonia, Fe²⁺, Fe³⁺ and total organic carbon (TOC), as well as nitrous oxide (N₂O) were investigated using the iron-rich paddy soil in Jiangxi province, South China. Results demonstrated that the denitrification rate dropped while ammonia nitrogen content (NH₄⁺-N) showed a rapid accumulation in the drying period. In the rewetting period, organic carbon played two-side roles. Organic carbon and ferrous iron together provided electron donors to denitrification, and organic carbon simultaneously reduced ferric iron under anaerobic environment. There were complex interactions among organic carbon, nitrate and Fe²⁺/Fe³⁺ under drying-rewetting cycles. Soil rewetting led to denitrification flush, especially after a moderately long drying period, while excessively frequent drying-rewetting alternation was not favorable to nitrate denitrification. Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

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21 pages, 3753 KiB

Open AccessArticle

Dynamics of Volumetric Moisture in Sand Caused by Injection Irrigation—Physical Model

by Amadeusz Walczak, Agnieszka Szypłowska, Grzegorz Janik and Grzegorz Pęczkowski

Water 2021, 13(11), 1603; https://doi.org/10.3390/w13111603 - 06 Jun 2021

Cited by 2 | Viewed by 3353

Abstract

The study was aimed at the determination of the dynamics of spatial distribution of moisture front, caused by pointwise application of water under conditions of high pressure. This was effected through a series of simulations of water injection to a porous material with [...] Read more.

The study was aimed at the determination of the dynamics of spatial distribution of moisture front, caused by pointwise application of water under conditions of high pressure. This was effected through a series of simulations of water injection to a porous material with particle size distribution corresponding to that of sand. The study was composed of six independent experimental series in which the sand monolith was supplied with water doses of 250, 500, 750, 1000, 1250, and 1500 cm³ under pressure (4 bar). At the same time, measurements of volumetric moisture were conducted with the use of TDR sensors, which were positioned within the soil in a regular grid pattern. It was demonstrated that the primary cause of water movement at the moment of injection is the pressure potential gradient of water molecules. The spatial reach of moisture change in relation to the injected water dose was also defined. It was also observed that in the course of water injection there is a risk of disturbing the structure of the porous material. The correctness of the adopted method was verified through the calculation of the water balance. Full article

(This article belongs to the Special Issue Study of the Soil Water Movement in Irrigated Agriculture Ⅱ)

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