Kostiakov Infiltration Models Research Articles

Experimental Investigation of the Different Polyacrylamide Dosages on Soil Water Movement under Brackish Water Infiltration.

The use of soil conditioners in conjunction with brackish water irrigation is critical for the efficient development and use of brackish water as well as the enhancement of the structure of saline soil and stimulating crop growth. This study investigated the effects of different polyacrylamide (PAM) dosages (0, 0.02%, 0.04%, and 0.06%) on the water flow properties of sandy loam during brackish water infiltration using one-dimensional vertical and horizontal soil column infiltration experiments. The results showed that: (1) PAM could lower the soil infiltration rate and increase soil water retention performance under brackish water infiltration conditions. (2) PAM had a significant effect on the parameters of the Philip and Kostiakov infiltration models. The soil sorption rate S and the empirical coefficient λ were the smallest, and the empirical index β was the largest when the PAM dosage was 0.04%. (3) PAM dosage displayed a quadratic polynomial connection with the soil saturated water content and the saturated hydraulic conductivity. The soil saturated water content was highest when the PAM dosage was 0.04%, the intake suction hd of the Brooks-Corey model increased by 15.30%, and the soil water holding capacity was greatly improved. (4) Soil treated with PAM could absorb more water under the same soil water suction, whereas the soil unsaturated hydraulic conductivity and its growth rate decreased. The soil saturated diffusion rate Ds, as well as the soil water diffusion threshold, rose. Finally, the 0.04% PAM dosage could improve soil hydrodynamic characteristics under brackish water infiltration, which is beneficial for the efficient utilization of brackish water.

Soil physical and chemical properties affected by long-term grazing on the desert steppe of Inner Mongolia, China

It remains unclear how long-term and different intensities of grazing affect the soil infiltration process, total nitrogen (TN), organic carbon (SOC), and grain size of desert steppes of Inner Mongolia, China. We quantified the effects of consecutive years of grazing from 2004 to 2018 on the soil particle size distribution (PSD, using the American soil classification system), mean soil infiltration rate (r), and cumulative infiltration volume (VC), in addition to the contents of SOC and TN, and their ratio (C/N). We defined grazing intensity at four levels, as non-grazed enclosure (NG, 0-), light (LG, 0.15-), moderate (MG, 0.30-), and heavy grazing (HG, 0.45 sheep per month per hectare steppe). The annual grazing period lasted from May to November. We established twelve adjacent experimental plots containing three replications for each grazing intensity. In July 2018, we collected 600 soil samples (0–40 cm soil depth: 4 depths with a 10–cm interval) in the plots (50 per plot) in a sigmoid configuration, to determine the PSD, SOC, TN, and C/N. Grazing evidently changed the PSD in diameter ranges of 20–150 (fine particles) and 200–500 μm (coarse particles). Grazing significantly decreased the uniformity and distribution range of PSD but increased its dispersion, and these changes were most pronounced in the topsoil (0–10 cm depth). LG promoted r and VC, whose augmentation was evident within the initial 10 min of the infiltration process. The Kostiakov infiltration model was better at dynamically and quantitatively fitting the changing process of r than either the Horton or Philip model. Compared with NG, LG and MG significantly increased both SOC and TN (p < 0.01) whereas these were significantly decreased under HG (p < 0.01). Across differing grazing intensities, topsoil SOC contents can be well predicted by the range and heterogeneity of PSD, as well as the fraction of fine soil particles. These results are helpful for better understanding how continuous grazing impacts soil characteristics and for specifically enacting reasonable grazing scenarios to mitigate desertification on vulnerable desert steppes.

Impacts of application patterns and incorporation rates of dredged Yellow River sediment on structure and infiltration of saline-alkali soil

Soil salinization is an issue of global concern. Despite recent evidence indicates that application of sediments into saline-alkali soil in Yellow River Delta as an additive can increase crop yield, its effects on soil structure and infiltration remain uncertain. In this study, the comprehensively analyses were conducted on the soil infiltration and microstructure of the soil treated with three sediment application layers (surface layer at 0-15 cm, lower layer at 15-30 cm, and plough layer at 0-30 cm) and four sediment incorporation rates (0, 2%, 5% and 10%), using soil column simulation experiment. Results indicated that the dredged Yellow River sediments can improve the infiltration capacity of saline-alkali soil; and the infiltration capacity increased with the rising sediment incorporation rate under the given application pattern. Compared with the control, applying dredged Yellow River sediments at 10% rate at lower layer and plough layer significantly facilitated the soil infiltration of the saline-alkali soil. Soil macro-porosity for T2, T5 and T10 was 26%, 52% and 158% more than that for the control, respectively. This phenomenon was attributed to the increased soil macro-porosity, due to the improved soil microstructure with the incorporation of sediment into the saline-alkali soil. Moreover, the cumulative infiltration was fitted better with Kostiakov infiltration model than Horton and Philip models. Keywords: saline-alkali soil, Yellow River sediment, soil infiltration, microstructure, incorporation rate, application pattern DOI: 10.25165/j.ijabe.20221504.6556 Citation: Li K S, Kong W H, Xu W S, Liu C X. Impacts of application patterns and incorporation rates of dredged Yellow River sediment on structure and infiltration of saline-alkali soil. Int J Agric & Biol Eng, 2022; 15(4): 139–146.

Comparison between different infiltration models to describe the infiltration of permeable brick pavement system via a laboratory-scale experiment.

The permeable brick pavement system (PBPs) is one of a widely used low impact development (LID) measures to alleviate runoff volume and pollution caused by urbanization. The performance of PBPs on decreasing runoff volume is decided by its permeability, and it was general described by hydraulic conductivity based on Darcy's law. But there is large error when using hydraulic conductivity to describe the infiltration of PBPs, and which infiltration process is not following Darcy's law, so it is important to find more accurate infiltration models to describe the infiltration of PBPs. The Horton, Philip, Green-Ampt, and Kostiakov infiltration models were selected to find an optimal model to investigate infiltration performance of PBPs via a laboratory-scale experiment, and the maximum absolute error (MAE), Bias, and coefficient of determination (R2) were selected to evaluate the models' errors via fitting with experiment data. The results showed that the fitting accuracy of Kostiakov, Philip, and Green-Ampt models was significantly affected by the monitoring area and hydraulic gradients. Meanwhile, Horton model fitted well (MAE = 0.25-0.32 cm/h, Bias = 0.07-0.11 cm/h, and R2 = 0.98-0.99) with the experiment data, and the parameters of the Horton model often can be achieved by monitoring, such as the maximum infiltration rate and the stable infiltration rate. Therefore, the Horton model is an optimal model to describe the infiltration performance of PBPs, which can also be adopted to evaluate hydrological characterization of PBPs.

Effects of crude oil pollution on soil moisture infiltration with loessial soil and aeolian sandy soil

Crude oil may block soil pores, affect soil water repellency, and change soil water movement. In this study, soil column simulation was used to study the effects of different crude oil pollution levels (0, 0.5%, 1%, 2%, 4%) on the water infiltration processes in loessial soil and aeolian sandy soil. The results showed that soil wetting front speed and infiltration rate of those two soils decreased with increasing crude oil content. The time needed for wetting front reaching the bottom of the soil column was the longest under 4% crude oil polluted soil, which was 4 times and 48 times longer than that of no crude oil polluted soil for loessial soil and aeolian sandy soil, respectively. The cumulative infiltration of loessial soil decreased with increasing crude oil content, while it increased to the max and then decreased as the crude oil content increased in aeolian sandy soil. The cumulative infiltration curves of aeolian sandy soil with high crude oil contents (2% and 4%) presented "up-tail" phenomenon. Kostiakov infiltration model and Philip infiltration model could better fit the infiltration process than Green-Ampt model for loessial soil with different crude oil content. However, the two models could only well fit the infiltration process for aeolian sandy soil with low crude oil content (0, 0.5%, 1%). Crude oil pollution could significantly affect soil water infiltration process, especiall in aeolian sandy soil.

Comparison of infiltration models to describe infiltration characteristics of bioretention

Bioretention is one of low-impact development measures, which widely used not only because it can reduce stormwater runoff total volume, decrease peak flow rate and delay peak flow time, but also can remove the runoff pollutants. Infiltration is an important hydrological process for bioretention to evaluate its runoff total volume reduction and pollutants removal. So, it is important to find an optimal infiltration model that can well describe the infiltration performance of bioretention. The Horton, Philip and Kostiakov infiltration models were selected to compare their accuracy when using for describe the infiltration characteristics of bioretention, and the errors between the different models simulate results and experiment results were assessed via the maximum absolute error (MAE), bias and coefficient of determination (R2). The experimental results showed that Horton model is fitting well and flexible under different experiment conditions, especially when the hydraulic head was 10 cm, with MAE of 0.50–0.81 cm/h, bias of 0.1–0.23 cm/h and R2 of 0.98–0.99. R2 of the Philip and Kostiakov models were all over than 0.87 at the initial infiltration period, but the model fitting accuracy decreased significantly with infiltration time elapse. Furthermore, the total runoff volume capture ratio and emptying time were advanced used to evaluate the flexibility of Horton model, and the Nash-Sutcliffe efficiency coefficients of them were over than 0.61 and 0.58, respectively. Therefore, the Horton model can be optimal selected to describe the infiltration process of bioretention and for its hydrological evaluation.

Study on the Influence of Fertilizer Solution Concentration on Soil Water and Nitrogen Transport Characteristics Under Film Hole Irrigation

Film hole irrigation is a new technique in agricultural production, which can improve water conservation and increase soil temperature. The purpose of this study was to disclose the effects of fertilizer solution concentration (c) on soil water and nitrogen transport characteristics under muddy water film hole infiltration. The laboratory experiments were conducted with muddy water film hole infiltration, using five fertilizer solution concentration treatments (c = 0, 300, 600, 900, and 1200 mg L−1). The cumulative infiltration, migration distance of the wetting front, soil moisture content, and $$ \mathrm{N}{\mathrm{O}}_3^{-}-\mathrm{N} $$ and $$ {\mathrm{NH}}_4^{+}-\mathrm{N} $$ contents in the wetted body were observed. The models about (i) the relationship between the cumulative infiltration volume per unit film hole area (I(t)) and infiltration duration (t) and (ii) the relationship among the horizontal and vertical migration distances of the wetting front (Fx, Fz), c, and t were established. The results showed that fertilizer solution concentration (c) had a significant effect on I(t), Fx, Fz, and moisture distribution in the wetted body. Cumulative infiltration volume per unit film hole area and infiltration duration conformed to the Kostiakov infiltration model (R2 > 0.98, P < 0.05). $$ \mathrm{N}{\mathrm{O}}_3^{-}-\mathrm{N} $$ is mainly distributed in the range of the wetting radius 12 cm, while $$ {\mathrm{NH}}_4^{+}-\mathrm{N} $$ is mainly distributed in the range of the wetting radius 6 cm. This study could provide a theoretical basis and technical support for fertilizer solution infiltration under muddy water film hole irrigation.

Analysis of soil physical properties and infiltration rates for various landuses at Gunung Dahu Research Forest, Bogor District, West Java Province

Assessment of the ability of the soil to absorb water can be known from the value of the infiltration rate. This study was conducted to examine the physical properties of soils and infiltration rates, analyze the relationship between physical properties of soils and their infiltration rates and determine the best infiltration models for various land uses. The data is processed using the Horton and Kostiakov infiltration model. Correlation analysis and R tests were performed to compare the field infiltration rate with the model prediction results. The results showed that the physical properties and infiltration capacity in the three land uses differed significantly on several parameters of physical properties such as drainage pore, permeability and infiltration with sequential values in the stands of S. leprosula, S. selanica and tourism objects were 3.21%, 2.29%, 3.51% for the parameters of fast drainage pores and 7.84%, 8.67%, 7.49% for slow drainage pore. Whereas the average permeability values are 1.37 cm / hour, 2.13 cm / hour, 3.39 cm / hour. Based on the results of field infiltration measurements, it was found that the S. selanica stands had the highest infiltration rate with a value of 15.5 cm / hour. The results of the correlation test and regression test between the field infiltration rate and the Horton infiltration model rate were not significantly different so that the Horton infiltration model can be used for the infiltration rate of soils in the Gunung Dahu Research Forest.

Effect of Moistube Fertigation on Infiltration and Distribution of Water-Fertilizer in Mixing Waste Biomass Soil

A series of indoor soil box simulation experiments were carried out to investigate the infiltration capacity of fertilizer solution in mixing waste biomass and the distribution characteristics of water-fertilizer in wetted soil under moistube fertigation. The infiltration rate and cumulative infiltration of moistube fertigation in soils as well as the distribution characteristics of water-fertilizer (soil water, nitrate–N, available P, and available K) in wetted soil were studied in three waste biomass (peanut shell) mixing ratios (MR1.5%, MR3.0%, and MR4.5%) taking a not amended soil as control (CK). The cumulative infiltration of fertilizer solution and the distribution of water-fertilizer were fitted by a modified infiltration model. Results indicated that increasing the mixing ratio improved significantly the infiltration rate and cumulative infiltration of fertilizer solution and the distribution area and content of water-fertilizer in amended wetting soil compared with CK. The relationship between the cumulative infiltration of fertilizer solution and infiltration time conformed to the Kostiakov infiltration model. The distribution uniformity coefficient of soil water and nitrate–N increased with the increase in waste biomass mixing ratio, whereas available P and available K decreased in wetted soil. The 4-parameter log-logistic model fitted well with the distribution of water-fertilizer in mixing waste biomass wetted soil under moistube fertigation. The research results could provide a theoretical basis and practical reference for the popularization and application of new moistube fertigation technology.

Effects of land use change and seasonal variation in the hydrophysical properties in Vertisols in northeastern Mexico

AbstractThe impact of the use of natural resources associated with anthropogenic activities has increased evidently, mainly through land use changes which have altered hydrophysical properties of soils. We hypothesized that, in the same soil type (Vertisol), four types of land use system (grassland, agricultural, Eucalyptus plantation and thornscrub) and seasonal variation can modify the soil hydrophysical properties. Results showed significant differences between land use systems and seasons for hydraulic conductivity (K), infiltration capacity (fp) and cumulative infiltration (fc). There were no seasonal differences in soil penetration resistance (SPR), bulk density (ρd) and total porosity (φP). Grassland presented higher values for ρd (1.2 g cm−3) and SPR (5.3 kg cm−2) and lower for K (0.8 × 10−5 cm s−1) and φP (53%), unlike thornscrub. Agriculture presented lower SPR (0.4 kg cm−2), while plantation showed similar values when compared to the thornscrub. Kostiakov infiltration model was fitted to land use infiltration curves, showing differences between land use and season. The values for fp oscillated between 53.6 and 548.8 mm hr−1 and fc ranged from 105.3 to 1,061 mm. The order of the infiltration values goes as follows: agriculture &gt; plantation &gt; thornscrub &gt; grassland. Land use changes in Vertisols induced modification of soil physical properties affecting processes like permeability, soil compaction and water availability.

WATER INFILTRATION OF COVERING SOILS WITH DIFFERENT TEXTURES AND BULK DENSITIES IN GRAVELMULCHED AREAS

To determine the influence of different bulk densities and texture on soil water infiltration after remediation in gravel-mulched areas, we subjected two different soil types were to a battery of tests to determine their soil infiltration characteristics. The results show that the soil infiltration capacity decreases with increasing soil bulk density. A logarithmic negative correlation was identified between stable infiltration rate and the bulk density of the two soils (R2 > 95%). Moreover, the larger the bulk density, the smaller the cumulative infiltration, and there is a significant linear negative correlation between density and infiltration. The Kostiakov infiltration model better describes the infiltration process of the Lou soil at all stages and the infiltration of Yellow-brown soil before 40 min. Finally, as soil water is redistributed, and its content increases with soil depth, and the greater the bulk density, the greater the water storage capacity of the soil from 0 to 30 cm. Overall, the soil bulk density should be no less than 1.5 g/cm3 when Lou soil is chosen to cover on gravel-mulched land, and not less than 1.4 g/cm3 for Yellow-brown soil.

Excel Approach for Infiltration Capacity for Different Lands

This paper presents an Excel approach for infiltration capacity for different types of lands. That is to employ the popular Microsoft Excel software to represent the measured infiltration data graphically. Regression analysis is performed for the accumulated infiltration versus the time. Equations are obtained to predict the accumulated infiltration at required times.&#x0D; Thirty one raw infiltration measurements from various sources are gathered, studied and analyzed applying this approach. Measurements include different types of soil textures and land covers. The infiltration rates are measured by the commonly used infiltrometer. Both single infiltrometer and double infiltrometer are employed.&#x0D; It is concluded that the presented Polynomial infiltration model of Excel approach for the accumulated infiltration is associated with high accuracy, where the values of coefficient of determination (R2) range between 0.9850 and 0.9998. The obtained equations can help in irrigation processes.&#x0D; All the gathered raw experimental infiltration measurements are also analyzed employing Horton and Kostiakov infiltration models. It is found that the Polynomial infiltration model of Excel approach has higher accuracy, followed by Kostiakov model, and finally Horton model. The values of different constants of Horton and Kostiakov infiltration models for all cases are obtained. The accuracy of the Polynomial, Horton and Kostiakov infiltration models are studied considering the types of soil texture and land cover.&#x0D; Investigating the constants A, B and C of the obtained equation of the polynomial infiltration model of Excel approach, it is found that all A values are negative, all B values are positive, and all C values are positive except for sandy clay and sandy clay loam soils. There is no specific trend for the effect of the associated land cover on constants A, B, and C except for loamy sand soil, where B and C values for bare land are greater than their values for irrigated land.

An Improvement to the Waterfront Advance–Time Relation for Irrigation Borders

AbstractUsing the Kostiakov, modified Kostiakov and improved modified Kostiakov infiltration models, three alternate solutions of the Philip and Farrel equation are suggested for the determination of waterfront advance–time relations for irrigation borders. To test the solutions with field data of waterfront advance–time relations, each accumulated infiltration–time relation was used in the Philip and Farrel equation and the waterfront advance–time relation was determined using six observed data sets on irrigation borders. The results show that the improved modified Kostiakov model performed best in prediction of accumulated infiltration time as well as the waterfront advance–time relation as compared with the modified Kostiakov and Kostiakov infiltration model. Also, the modified Kostiakov infiltration model performed better in prediction of the infiltration and advance–time relation as compared to Kostiakov. Hence this paper suggests the use of the improved modified Kostiakov infiltration model in the Philip and Farrel equation with the help of computer programs to determine the waterfront advance–time relation in irrigation borders most accurately, as compared to the modified Kostiakov and Kostiakov infiltration models. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Irrigation potential of Inuakpa in Odukpani local government of Cross river using Kostiakov model

Infiltration measurements were carried out using cylindrical infiltrometer with height and diameter of 15cm and 5cm respectively. Sixteen infiltration runs were carried out in a composite grid (30m x 30m) in Inuakpa, Odukpani Local Government Area of Cross River State to test the efficiency of Kostiakov’s model, measure infiltration rate and relate same to some soil physical properties. Mean infiltration rate of 9.01 cmhr-1 was obtained at the end of the runs. The soil textural class was loamy sand with particle size distribution indicating mean values of 82.4, 7.2 and 10.4 % for sand, silt and clay respectively. The bulk density, particle density and total porosity had mean values of 1.35 Mgm-3, 2.48 Mgm-3 and 44.86 % while their coefficients of correlation with infiltration rate where 0.58, 0.48 and 0.69 respectively. There were also linear and positive relationships between infiltration rate and sand and silt contents with coefficients of correlation of 0.92** and 0.55* (p ≤ 0.05) respectively while clay content was not specifically linear or positive. Kostiakov infiltration model fitted well in evaluating infiltration parameters for sustained agricultural production. The soil infiltration rate, physical and chemical properties studied placed the soil in class 2 - irrigable. Mulching with plant residues, cover cropping, the use of restorative crops and zero tillage should be practiced in the area as soil management strategies.

A Forecasting Method of Kostiakov Infiltration Model Parameters Based on Back-Propagation Model

Based on test data of field soil water infiltration, Back-propagation (BP) model of predicting Kostiakov infiltration model parameters was established after analyzing the primary influence factors of water infiltration model parameters. The results indicate that BP model can reflect the non-linear relationship between the model parameters and the physical parameters of the soil; BP model is high accuracy for prediction soil infiltration model parameters. It can be referred as a new method to predict soil infiltration process using soil physical parameters.

不同初始含水率下粘质土壤的入渗过程

Soil infiltration is the basic hydrological process for water penetrating into the soil,and the amount of water infiltrating the soil surface directly affects the quantity of surface runoff and soil erosion,even the recharge of both soil and underground water.The initial soil water content is an important factor to soil infiltration,and its role in runoff controlling and soil erosion prevention has been taken into account by many researches.In this study,the double-ring infiltration method was used to quantitatively measure the infiltrability of surface soil(0—5 cm depth) covered with forestland and grassland,which were under two antecedent soil water contents of 12% and 40%,respectively.In addition,the changes of soil infiltration process over time were estimated with different infiltration models. The results indicated that the initial soil infiltration rate of forestland and grassland tended to decrease with increasing initial soil water content.And an increase in initial soil water content results in an increase in steady infiltration rate and cumulative infiltration rate.Whether forestland or grassland,soil infiltration process with higher initial soil water content reaches the steady infiltration stage earlier than that with lower initial soil water content.For forestland with initial soil gravimetric water content rate of 12%,the initial soil infiltration rate was 8.95 mm/min,which was four times to the initial infiltration rate for forestland soil with gravimetric water content rate of 40%.However,its steady infiltration rate 0.24 mm/min was only one eighth of the forestland with initial soil gravimetric water content rate of 40%,and the cumulative infiltration in an hour was only two thirds of that.This phenomena may attribute to the faster wetting rate of drier soil in infiltration process,which cause stronger slaking forces of the soil and severe aggregates breakdown,enhance surface sealing or promote the destruction of soil structure,and then significantly decrease the soil infiltrability. For grassland surface soil with ample organic matter,soil infiltrability and infiltration process suggested lower sensitivity to initial soil water content.Initial infiltration rate,steady infiltration rate,and one hour cumulative infiltration of grassland with 12% soil water content were 2.21 mm/min,0.62 mm/min,59.16 mm,respectively.And these parameters of grassland with 41% soil water content were 2.07 mm/min,1.7 mm/min,110.27 mm,which suggested less significant difference than that of forestland.Whether covered with forestland or grassland,soil instant infiltration rate decreased rapidly at the beginning of the infiltration process,and then decreased approximately linearly with time until approached to constant,especially under the condition of the initial soil water content to be 12%.The least square method was used to simulate the infiltration rate changes with time,and the results indicated that soil infiltration process of forestland and grassland were all fitted better by Horton and Kostiakov infiltration models than by Philip infiltration model.Besides,Horton infiltration model was the best model to describe soil infiltration process,which made it suitable to describe the soil infiltration process of forestland and grassland in the Three Gorges Reservoir area.

Infiltration Evaluation Strategy for Border Irrigation Management

Water infiltration into soil plays a vital role in the performance of surface irrigation. Real-time information on infiltration characteristics is necessary to use surface irrigation models to manage irrigation systems. The present field study deals with the evaluation of the Kostiakov infiltration parameters using water front advance information at three different locations (50, 75, and 100% of the field length) along the alfalfa irrigated borders. Two irrigations were conducted on four border checks. The parameters of the Kostiakov infiltration model were determined using the one-point and two-point methods for these locations. The infiltration parameters for each border were used in a surface irrigation model to evaluate their impact on irrigation performance measures. The mean irrigation performance measures, such as inflow volume, application efficiency, tailwater ratio, deep percolation ratio, and low quarter distribution uniformity, were significantly different for one-point and two-point methods. However, the mean performance measures were not significantly different for infiltration functions evaluated at three different locations using the two-point method. Furthermore, performance of individual irrigation events was in close agreement for all three locations. Thus, infiltration parameters can be estimated using the water front advance information up to 75% of the field length (to reduce the impact of soil spatial variability) and can be used to predict irrigation performance measures reasonably well. A cutoff strategy that ensures the advancement of the wetting front to the downstream end of the field was devised on the basis of the infiltration parameters evaluated at 75% of the field length. This cutoff strategy resulted in savings of applied water (18%) and reduction in both tailwater and deep percolation losses, which gave higher application efficiency. The methodology presented in this article has the potential for use in real-time management of border irrigation systems.

A Modification to Kostiakov and Modified Kostiakov Infiltration Models

Incorporating the time variant function of the otherwise used as steady infiltration rate, this paper presents revised versions of the popular and frequently used Kostiakov and modified Kostiakov infiltration models. The proposed, along with the existing, versions are tested on 40 datasets of infiltration observed on five different soils in India and USA The former indicated an improved performance over their respective existing versions. Further generalization of the improved modified Kostiakov model incorporating time to ponding showed an enhanced performance on all the soils.

Influence of Stiff‐Stemmed Grass Hedge Systems on Infiltration

The ability of grass hedge systems to reduce runoff is critical to their effectiveness in controlling soil erosion. The reduction in runoff depends on the infiltration properties of soil managed with hedges. The objective of this study was to evaluate the effects of stiff‐stemmed grass hedges on infiltration. The experiment was conducted on a site, which had been managed with switchgrass (Panicum virgatum L.) hedges for 10 yr at the USDA‐ARS research station near Treynor, IA. The predominant soil was Monona silt loam (fine‐silty, mixed, superactive, mesic Typic Hapludolls). Ponded infiltration measurements were used to determine field‐saturated hydraulic conductivity (Kfs). Three positions were sampled: within grass hedges, within a deposition zone 0.5 m upslope from grass hedges, and within a row crop zone 7 m upslope from the hedges in soybean (Glycine max) production during 2001 and corn (Zea mays L.) production during 2002. A tension infiltrometer was used to measure infiltration at three selected tensions (50, 100, and 150 mm) in the grass hedge and row crop positions. The physically based Parlange, the Green and Ampt, and the empirically based Kostiakov infiltration models fit the measured data well (r2 = 0.99–1.00). The Kfs within the grass hedge position was more than seven times greater than in the row crop position and 24 times greater than in the deposition position. The infiltration rate at 50‐ and 100‐mm tension in the grass hedge position was significantly larger (P &lt; 0.01) than in the row crop position; values at 150‐mm tension were not significantly different. The Kfs was found to be similar in magnitude to laboratory measured saturated hydraulic conductivity (Ksat) treated with bentonite to eliminate by‐pass flow. Grass hedges were found to enhance water infiltration compared with conventional row crop management.