Amount Of Drainage Water Research Articles

Use of satellite data and GIS for soil mapping and monitoring soil productivity of the cultivated land in El-Fayoum depression, Egypt

The aims of this study are: (1) producing a geometrically corrected physiographic–soil map scale 1:50,000 reduced to the attached map for the studied area; and (2) monitoring soil productivity of the cultivated land in El-Fayoum depression. To fulfill these aims, 16 soil profiles were chosen to represent the different mapping units. Morphological description was carried out and soil samples were collected for physical and chemical analysis. Based on ETM images analysis and the geographic information system, coupled with the field work and laboratory analysis data, the physiographic–soil map was produced. The following main landscape units can be identified: 1. alluvial plain; 2. fluvio-lacustrine plain; 3. lacustrine plain. This study is based on comparing between the data extracted from previous study carried out in 1961 by RISW report and the data resulting from the current study to monitoring soil productivity in the studied area to make comparison as well as monitoring more realistic. Soil characteristics and productivity criteria are matched for getting soil productivity in the period 1961–2010. Monitoring of soil productivity includes the following main landscapes, i.e., lacustrine plain, fluvio-lacustrine plain, and alluvial plain. The soil characteristics of previous and current study were grouped and recalculated to meet the requirements of Riquier et al. (1970) modified by FAO (2007). The results reveal that: Generally, all the studied sites in El-Fayoum depression changed positively in the productivity grade except that the soil of lacustrine plain seems to be still degradable for the reason that it receives a lot amount of drainage water from all the soil of the depression. The improvement of the soil productivity grade in the studied area due to the good quality of land management such as: – sub-soil plugging and adding organic materials to overcome soil compaction; – establish drainage network system to reduce water logging; – leaching processing to remove the excess of salinity occurs in the studied area; – gypsum addition considering gypsum requirements to reduce soil alkalinity.

Distributed agro-hydrological modeling with SWAP to improve water and salt management of the Voshmgir Irrigation and Drainage Network in Northern Iran

Abstract The agro-hydrological model SWAP was used in a distributed manner to quantify irrigation water management effects on the water and salt balances of the Voshmgir Network of North Iran during the agricultural year 2006–2007. Field experiments, satellite images and geographical data were processed into input data for 10 uniform simulation areas. As simulated mean annual drainage water (312 mm) of the entire area was only 14% smaller than measured (356 mm), its distribution over the drainage units was well reproduced, and simulated and measured groundwater levels agreed well. Currently, water management leads to excessive irrigation (621–1436 mm year −1 ), and leaching as well as high salinity of shallow groundwater are responsible for large amounts of drainage water (25–59%) and salts (44–752 mg cm −2 ). Focused water management can decrease mean drainage water (22–48%) and salts (30–49%), compared with current water management without adverse effects on relative transpiration and root zone salinity.

Wireless lysimeters for real-time online soil water monitoring

Identification of drainage water allows assessing the effectiveness of water management. Passive capillary wick-type lysimeters (PCAPs) were used to monitor water flux leached below the root zone under an irrigated cropping system. Wireless lysimeters were developed for web-based real-time online monitoring of drainage water using a distributed wireless sensor network (WSN). Twelve PCAP sensing stations were installed across the field at 90 cm below the soil surface, and each station measured the amount of drainage water using two tipping buckets mounted in the lysimeter and continually monitored soil water contents using two soil moisture sensors installed above the lysimeter. A weather station was included in the WSN to measure micrometeorological field conditions. All in-field sensory data were periodically sampled and wirelessly transmitted to a base station that was bridged to a web server for broadcasting the data on the internet. Communication signals from the in-field sensing stations to the base station were successfully interfaced using low-cost Bluetooth wireless radio communication. Field experiments resulted in high correlation between estimated and actual drainage with r2 = 0.95 and confirmed a reliable wireless communication throughout the growing season. A web-linked WSN system provided convenient remote online access to monitor drainage water flux and field conditions without the need for costly time-consuming supportive operations.

Salt and water balance analysis after adopting controlled drainage in Yinnan Irrigation District, Ningxia, China

AbstractAccording to data collected from a field experiment of controlled drainage in Yinnan Irrigation District, this paper analyses the amount of drainage water and variation of salt and water balance. Compared with traditional drainage, it is found that the volume of drainage water is obviously reduced by controlled drainage. The groundwater table in the controlled drainage areas is 1.8 cm higher than that in the traditional drainage areas. If drainage velocity is used to substitute for the volume of drainage water, the total volume of drainage water drained from controlled drainage areas is on average 50% less than that from traditional drainage areas. At the same time, the volume of underground drainage water decreases by 46%. By analysing the balance between salt and water in the controlled drainage areas, the introduced amount of salt is less than the discharged amount of salt, so salt and water are still kept in good status. Copyright © 2008 John Wiley & Sons, Ltd.

Subsurface drainage and salt leaching in irrigated land in south‐east Turkey

AbstractWith respect to the expansion of waterlogging and salinity increase in irrigated areas of Turkey, this study was conducted to monitor and assess the effects of a subsurface drainage system on salt leaching in the Harran plain. The field experiment was carried out near Akçakale province, in Şanlıurfa, from 2001 to 2004. The subsurface drainage system reduced the salinity by about 80% in the topsoil (20 cm depth), at the end of the experimental period. Winter precipitation had no significant effect on salt leaching. A statistically significant relationship was found between the amount of drainage water and the salt leaching (R2 = 0.970). An exponential relationship was further detected between drainage water (Ddw)/soil depth (Ds) vs. remaining salt/initial salt values (C/C0) (R2 = 0.764). Copyright © 2008 John Wiley & Sons, Ltd.

Influence of Plant, Soil, and Water on the Leaching Fraction

Reducing the amount of drainage water that contains salts, nutrients, and trace elements may reduce environmental contamination to groundwater by reducing the dissolution of trace‐element‐containing minerals, maximizing chemical precipitation of salts, and improving nutrient uptake efficiency. If salt accumulates, transpiration and yield will decrease and some fraction of the irrigation water will not be extracted by roots, subsequently becoming drainage. We modeled yield and salt and water budgets under conditions of extended irrigation with poor quality water in amounts ranging from 0.6 to 1.6 times the ratio of irrigation (I) to reference evaporation (E0). The surface boundary conditions were taken from a field experiment where melon (Cucumis melo ssp. melo cv. Galia) was irrigated with waters of electrical conductivities of 1.2, 3, 6, and 9 dS/m at I/E0 = 1.0 for a growing season (1152 h). The model contained one‐dimensional solutions to Richards' equation with a root‐sink term and the equation of continuity for salt transport. Solutes were treated conservatively. For any given salinity value, the leaching fraction had a minimum value corresponding to the irrigation level where a minimum amount of water was used to control salinity and those minimum values were 0.11, 0.24, 0.44, and 0.54 for salinity levels 1.2, 3, 6, and 9 dS/m. Yield reduction for these irrigation levels were 80, 70, 60, and 40% of maximum possible yields, suggesting an economic price to minimizing drainage and further suggesting that plant–irrigation–drainage relationships are highly self‐regulating.

El-Salaam Canal project, Sinai II. Chemical water quality investigations

The emphasis on increased reuse of drainage water for irrigation is essential as Egypt expands its agricultural base to meet the food requirements for rapidly population growth rate. The Government of Egypt implemented El-Salaam Canal project to reuse drainage water, to create new communities along the Canal and to re-charting Egypt's population map. Diverting considerable amounts of drainage water after blending of the Nile water to newly reclaimed areas for irrigation of 643,560 acres of new lands in the northeastern Delta and northern Sinai peninsula are planned by using El-Salaam Canal water. This paper is concerned with the physical and chemical properties of El-Salaam water. The study was carried out monthly from February 2004 to January 2005. Seven locations were selected to cover the sampling program monthly. The parameters measured were: water flow rate current, air and water temperature, pH, dissolved oxygen, conductivity, turbidity, COD, BOD, TDS, hardness as CaCO 3, total hardness. Na, K, Mg, Fe, bicarbonate, chloride, carbonate, hydroxide, sulfate phosphate and silicate were determined. The analyses indicated the variation of the quality of water from month to month. The canal water was characterized by high TDS, high values of heavy metals and high concentrations of dissolved organic compounds, so the study proved that the El-Salaam water canal is not suitable for irrigation and drinking purposes and needs treatment.

Modeling daily soil water dynamics during vertical drainage using the incoming flow concept

Abstract Crop management models require simulation of daily soil water dynamics. The objective of this study was to develop a model to simulate the daily soil water dynamics during vertical drainage with reasonable accuracy using the incoming flow concept. The execution of this model, which has been developed based on the conservation of mass law, consists of two steps. First, calculating the potential daily change of soil water content (Δ θ p) for each soil layer in the profile assuming each one receives no water from the above layer. Then, calculating the actual daily change of soil water (Δ θ a) for each soil layer in the profile by adjusting Δ θ p using the incoming water flow, which can be defined as the amount of drainage water that reaches a layer in a soil profile from the above layer. The model was compared with the Suleiman and Ritchie [Suleiman, A.A., Ritchie, J.T., 2004. Modifications to the DSSAT vertical drainage model for more accurate soil water dynamics estimation. Soil Sci. 169 (11), 745–757] vertical drainage model (SRVDM) and HYDRUS-1D for diverse soils and was tested using drainage experimental data of a Eutric Regosol in Bekkevoort, Belgium and a sandy soil in Georgia, U.S. The difference in Δ θ p between the new model and HYDRUS-1D for diverse soils ranged from − 0.01 to 0.016 m 3 m − 3 for the first day and from − 0.005 to − 0.025 m 3 m − 3 for the second day while the difference in Δ θ p between the SRVDM and HYDRUS-1D for these soils ranged from 0.014 to 0.062 m 3 m − 3 for the first day and from − 0.01 to 0.026 m 3 m − 3 for the second day. The relative maximum absolute errors in Δ θ a between the new model and HYDRUS-1D was 10% while the relative maximum absolute errors in Δ θ a between the SRVDM and HYDRUS-1D was 112%. In the experiments, the root mean square difference of the soil water content for the new model was lower than that for the SRVDM at the different soil depths. These results indicated that the new model outperformed the SRVDM in simulating Δ θ p and Δ θ a for diverse soil. It can be concluded that the new model was robust and reasonably accurate for diverse soils at different soil depths. The implementation of such model will improve the accuracy and applicability of regional soil water dynamics simulation and will reduce considerably the computational time and the required inputs.

Passive Capillary Sampler for Measuring Soil Water Drainage and Flux in the Vadose Zone: Design, Performance, and Enhancement

Various soil water samplers are used to monitor, measure, and estimate drainage water, fluxes, and solute transport in the vadose zone. Passive capillary samplers (PCAPs) have shown potential to provide better measurements and estimates of soil water drainage and fluxes than other lysimeters designs and field sampling methods. Twelve automated PCAPs with sampling surface dimensions of 31 cm width 91 cm long and 87 cm in height were designed, constructed, and tops of the samplers were placed 90 cm below the soil surface in a Lihen sandy loam (sandy, mixed, frigid Entic Haplustoll). The PCAPs were installed to continually quantify the amount of drainage water and fluxes occurring under sugarbeet (Beta vulgaris L.) and malting barley (Hordeum vulgare L.) crops treated with 30 mm (low replacement) and 15 mm (high replacement) irrigation frequencies. Drainage water was extracted, collected, and measured periodically (weekly from May to mid-August, biweekly until late September, and monthly thereafter until mid-November). This design incorporated Bluetooth wireless technology to enable an automated datalogger to transmit drainage water and flux data simultaneously every 15 min to a remote host. Real-time seamless monitoring and measuring of drainage water and fluxes was thus possible without the need for costly time-consuming supportive operations. The mean difference (Md) values between manually extracted and logged drainage water for high frequency (Md = 0.80 mm) and low frequency (Md = 0.26 mm) irrigations were small and not significantly different from zero. The Root Mean Square Error (RMSE) of 2.46 and 7.83 mm for high frequency and low frequency irrigations, respectively, were also small. Despite small variations in drainage water results, our novel PCAP design provided an accurate and convenient way to measure water drainage and flux in the vadose zone. Moreover, it offered a significantly larger coverage area (2700 cm2) than similarly designed vadose zone fluxmeters or PCAPs. In the course of one year's field testing, we incorporated several additional enhancements such as PCAP container, tipping bucket and datalogger unit, all of which we recommend for optimal performance.

A simple methodology for the evaluation of groundwater pollution risks

Groundwater represents a very significant source of fresh water for irrigation and drinking purposes and therefore preserving the availability and quality of this resource is extremely important. A first assessment of the amount of pollutants that can be exported to groundwater via soil drainage can be made by a) measuring the amount of contaminants present in the soil solution at the bottom of the soil after a prolonged simulated rainfall event, and b) estimating the amount of drainage water passing the soil bottom during a period of time long enough to include sufficient instances of both, wet and dry episodes inherent to the local climate. Drainage water was estimated by means of a simple infiltration model ("bucket model") which computes on a daily basis the inputs and outputs of soil water through rainfall and evapotranspiration generated by a stochastic model of the local climate along a period of 50-100 years. The methodology was applied in the Guadiamar valley after the toxic spill of a pyrite mine in Aznalcóllar (Spain). The results show that Zn is the dominant contaminant at the site with a 1.2 g m(-2)year(-1) contribution to groundwater. The presence of a gravel rich horizon below 50 cm depth reveals an increase in drainage and the threat to groundwater.

Water and salt balance studies, using SaltMod, to improve subsurface drainage design in the Konya–Çumra Plain, Turkey

Soil salinity and water logging are unavoidable processes in areas under excessive use of ground water and poor irrigation management. This study was undertaken to simulate the effect of different drain depths on the amount of drainage water, root zone salinity, and depth of water table in the Konya–Çumra Plain, Turkey. SaltMod model was tested with data collected from the Karkın pilot area. Effects of current irrigation–drainage practices on root zone salinity and drain discharge rate were evaluated. Data such as drain discharge, soil salinity, water table depth, and soil properties were collected. The soil salinity was not high in the test area, but there were commonly high water table and high salinity in the plain. The average soil salinity in the root zone decreased from 2.90 to 2.3 dS m −1 at the end of 4 year period. Simulation results indicated that the leaching efficiency is 0.7 and natural drainage is 0.120 m/year in the test area. When drain depth is considered to be as 1.20 m, 80% of the soils would have a salinity with electrical conductivity (EC) less than 2.72 and 2.71 dS m −1 for the first and second seasons, at the end of 10 year period. The drain depth in the test area was about 1.5 m. However, the assumed depth of 1.2 m appeared to be feasible.

Movement of suspended matter and a bromide tracer to field drains in tilled and untilled soil

Abstract. Drainage water was sampled intensively during a four‐year field experiment on a sandy loam soil subjected to four unreplicated tillage treatments: (1) harrowing with a springtine harrow, drilling; (2) direct drilling; (3) ploughing with light subsurface compaction, one pass with a PTO‐driven rotary harrow, drilling; (4) ploughing, one pass with a springtine harrow, drilling. In all years, the losses of suspended matter with drainage water (0.1–4.3 kg ha−1 yr−1) were smaller by a factor of 1.9 or more from direct drilled plots than from plots subjected to the other tillage treatments, strongly suggesting that tillage increased the losses. Annual bromide losses were governed by the amount of drainage water rather than by the tillage treatments. However, after one drainage season, more bromide was left in the soil at 0–100 cm depth with ploughless tillage than with ploughing, thus indicating more bypass flow without ploughing. The study demonstrated very changeable patterns of suspended matter and bromide concentrations in drainage water sampled from large field plots, and questions the representativeness of drainage water samples for water reaching the subsoil or shallow groundwater.

Effect of field groundwater table control on water and salinity balance and crop yield in the Qingtongxia Irrigation District, China

AbstractThe Qingtongxia Irrigation District (QID) is one of the key agricultural bases in the Yellow River Basin. It is located in the upstream part of the Yellow River in the north of China and covers about 350 000 ha of farmland. The climate in the district is arid and semi‐arid. The annual average precipitation is about 200 mm. Water shortage is one of the main restrictions on agricultural development. In recent years, large amounts of water have been drawn from the Yellow River, which not only contributes to the severity of water shortages in the middle and downstream part of the Yellow River Basin, but also leads to the rise of the groundwater table and related waterlogging and salinization of the farmland.This article focuses on the analysis of the effects of field groundwater table control under different irrigation water amounts on the soil water and salinity content and on relative crop yield. Two experimental areas, Pingluo and Huinong, were selected to collect the required field data. The agro‐hydrological model SWAP was used to analyse the water flow and salt transport for different groundwater table and irrigation scenarios. Six scenarios, which resulted from two groundwater table regimes combined with three irrigation amounts, were simulated. The groundwater table regimes represent the present and future target groundwater table situation and the three irrigation amounts represent different water‐saving options. Waterlogged land is also simulated. The results show that: High regional groundwater tables are the main reason for the large amount of drainage water and low crop yield. Due to the regional high groundwater table, reducing irrigation amounts in the field without lowering the field groundwater table will not lead to a large reduction of drainage water, and will cause a further reduction in crop yield. The salinity storage in the soil profile at the end of the growing season will increase when the irrigation amount is reduced, and when the groundwater table is lower. But the increase is very small. To lower the field groundwater to the target water table is an effective way to increase crop yield. Copyright © 2004 John Wiley & Sons, Ltd.

REAL-TIME MEASUREMENT OF DRAINAGE FROM POT-IN-POT CONTAINER NURSERIES

In pot-in-pot nursery production, information on the amount of drainage water loss from the pots due to irrigationand rainfall is beneficial to improving irrigation water use efficiency and optimizing nutrition management. An experimentalfield site was established to determine drainage water loss from pot-in-pot container nurseries with micro-irrigation. Thesite consisted of 50 container-grown trees, 10 tipping-bucket rain gauge units, and a portable weather station. Rain gaugeunits were calibrated four different ways to determine repeatability and reliability for real-time measurement of the drainagewater. Volume of water was calculated from the product of number of tips and volume per tip. Accuracy of measurements wasverified by the amount of drainage water collected weekly in collection buckets located under rain gauge units for variousirrigation applications and rainfall events. The maximum difference in the weekly amount of drainage water collected withthe collection buckets and measured with the rain gauge units was 1.215 L (or 5.3% error) when the daily irrigation applicationto five trees was 15.5 L. The system reported real-time measurement of drainage water due to irrigation and rainfall,and provided a research tool to evaluate strategies for nurseries to better manage irrigation schedules.

Salinity, drainage and selenium problems in the Western San Joaquin Valley of California

Highly productive, irrigated agriculturecan be found in California's Central Valleymade up of the Sacramento, San Joaquin, andTulare Lake basins. High water tablesthroughout much of the San Joaquin andTulare Lake portions of the Valley threatenthis highly productive region. Due totopographic and environmental constraintsmuch of the region is currently withoutdrainage. In 1990 State and Federalgovernment agencies combined to produce areport that outlined possible steps to dealwith the drainage issue. These stepsincluded: 1) Source control (practices toreduce the amount of drainage water); 2)Drainage reuse; 3) Evaporation systems; 4)Land retirement (cease irrigation); 5)Groundwater management; and 6) Discharge tothe San Joaquin River. General backgroundinformation to the history and hydrology ofthe Valley as well as a discussion of thefeasibility and constraints of providingdrainage by discharging drain water to theSan Joaquin River are presented. Inaddition a general discussion of thetechnical and political limitations ofproviding drainage in the River arediscussed.

Irrigation with saline water: benefits and environmental impact

The shortage of water resources of good quality is becoming an important issue in the arid and semi-arid zones. For this reason the availability of water resources of marginal quality such as drainage water, saline groundwater and treated wastewater has become an important consideration. Nevertheless, the use of these waters in irrigated lands requires the control of soil salinity by means of leaching and drainage of excess water and salt. However, the leaching of salts, soil microelements and agro-chemicals can lower the quality of the drainage water in the irrigation scheme. The irrigation return flows with water or poor quality are a source of pollution of the surface water bodies situated downstream of the drainage outlet. Deep percolation could also contaminate the groundwater. Therefore, irrigation with saline water requires a comprehensive analysis even beyond the area where water is applied. The problem should be treated beyond the scope of the irrigation scheme, taking into consideration the groundwater and downstream surface water resources of the river basin. Consequently, the sustainable use of saline water in irrigated agriculture requires the control of soil salinity at the field level, a decrease in the amount of drainage water, and the disposal of the irrigation return flows in such a way that minimizes the side effects on the quality of downstream water resources. This paper describes the guidelines for a preliminary evaluation of the suitability of water for irrigation and the key factors for salinity control in lands irrigated with saline water. Options to improve the quality of the drainage water, strategies for the reuse of this water and alternatives for disposal of the outflow are also analysed. The final goal is to obtain sustainable agriculture and maintain the quality of the water resources in the river basin.

Evaluation and Comparison of Five Simulation Models for Estimating Water Drainage Fluxes under Corn

AbstractThe simulation accuracies of five water quality models, LEACHW, MACRO, NCSWAP, SLIM, and SOIL to predict the amount of drainage water were evaluated and compared to field data from a 5‐yr leaching experiment. The study was conducted on Hagerstown silt loam soil (fine, mixed, mesic Typic Hapludalf). Drainage fluxes below the rooting zone of corn were measured with pan lysimeters in 1988–1989, 1989–1990, 1990–1991, 1991–1992, and 1992–1993. A series of 18 zero‐tension pan lysimeters (0.465 m2 area) were installed at a depth of 1.2 m to collect drainage water at approximately the rooting depth of corn. All five models were calibrated to the site conditions using data from 1989 to 1990. The calibrated inputs were then used to evaluate the models' simulating accuracy using 1988–1989, 1990–1991, 1991–1992, and 1992–1993 drainage data. The cumulative annual simulations of drainage water from each model were compared to the mean of pan efficiency corrected measured data for these five sampling years. Simulated results for all five models fell within 95% confidence intervals of the measured data. Validation simulations of drainage fluxes were about as accurate as calibration simulations. The statistical analyses indicated that all five models performed well and have the potential to accurately predict the amount of drainage fluxes below the 1.2 m depth under corn cropping system without the need to calibrate the model for each year. There were small differences among the overall performances of the models for simulating drainage losses, but these differences were not significant using one‐way analysis of variance.

Assessment of various control strategies for recirculation of greenhouse effluents under semi-arid conditions

SummaryRose plants (cv. Mercedes) were planted in tuff as soilless medium during April 1993. Recirculation of drainage water (DrW) was started in December 1993. Since then, three strategies were tested versus non-recirculated controls: a) Electrical conductivity (EC) of irrigation water of all treatments and the control was identical. This was achieved by diluting the recycled solution with various proportions of tap and collected rain water. As a first approximation, DrW were considered as containing full strength nutritional solution. As a result, the concentration (cone.) of applied nutrients was somewhat lower in the recirculation treatments than in the control. No DrW discharge was done, b) All treatments received a quantity of fertilizer solution identical to that of the control, regardless of the contribution of nutrients from the DrW. As a result, the cone, of K and N was considerably higher in the recirculation treatments than in the control. DrW was discharged whenever their EC passed prescribed values (3.0, 3.5, 4.0 or 4.5 dS m–1). c) Irrigation was controlled according to prescribed EC values of 2.0 (control), 2.5, 3.0 and 3.5 dS m–1 (recirculation treatments) using maximum possible amount of DrW. Excess DrW was discharged. The cone, of the fertilization solution was adjusted so that phosphate cone, in the DrW was similar to that of the control. The potential savings of water and fertilizers and the reduction in environmental pollution are described. No negative effect of DrW recycling on crop yield (quantity and quality) was found. Frequent monitoring revealed no proliferation of pathogenic microorganisms.

Cations adsorbed to soil organic matter ? A regulatory factor for the release of organic carbon and hydrogen ions from soils to waters

Surface waters in northern forest ecosystems receive a substantial amount of drainage water from superficial soil horizons enriched in organic matter (SOM). Chemical reactions in the interface between the soil solution andf organic colloides will therefore affect the surface water chemistry. The mobilization of total organic carbon (TOC) and pH was studied as a function of amounts of organically adsorbed Na, Ca and Al in two O and one A horizon, which differed in the likelihood of contributing to the chemistry in runoff, in a forested watershed in northern Sweden. The samples were hydrogen ion saturated, washed and titrated with NaOH, Ca(OH)2 and Al(OH)3 in a constant ionic medium of 0.01 M NaCl in order to give rise to a population of manipulated samples differing in the composition of adsorbed cations. The highly humified SOM accumulated in the Oh and Ah horizons of a Gleysol close to the draining stream was stabilized by flocculating Al (95% of adsorbed metal cations), which resulted in a low release of TOC. These horizons showed a high potential of organic carbon solubility when Al was changed for di- or monovalent cations. Calculations suggested that the release of TOC would increase more than ten times if Al was exchanged for Ca upon liming to pH 6.0. The pH values of all horizons were shown to be determined mainly by the composition of adsorbed mono-,di- and trivalent cations.

Simulation of bentazon leaching in sandy loam soil from mellby (Sweden) with the pestla model

Abstract Results of a lysimeter study on bentazon leaching in a sandy loam soil from Mellby (Sweden) were used to test the PESTLA model. To obtain a good description of the measured amounts of drainage water, the potential evapotranspiration rate (based on the Penman equation) had to be multiplied by 1.5 to 2. This comparatively large increase in potential evapotranspiration is probably the result of the surroundings of the lysimeter being dry for most of the experimental period. Using sorption parameters estimated from literature data resulted in the calculated leaching of bentazon to be much higher than the measured leaching. Using sorption parameters based on measured bentazon adsorption to the sandy loam soil resulted in a good explanation of the observed leaching of bentazon by the model.