Effectiveness of Wick Irrigation Method on Yield and Water Use Efficiency on Maize in Semi-Arid Area

Wick irrigation is a combination of subsurface and pot irrigation methods that provides water to the plant roots through the wick by means of capillary ascent. The salient features of this method are the elimination of evaporation losses and deep penetration, and thus increase plant yield and water use efficiency. The purpose of this study was to investigate the performance and water use efficiency of a wick system designed for corn cultivation in comparison with surface-furrow irrigation method. In this study, after reviewing and selecting the most suitable wick, field studies with two treatments of wick irrigation and furrow irrigation were performed in the summer of 2017 in one crop season and the wick system was prepared and implemented. Based on the results obtained, the total volume of water consumed in the wick system has decreased by about 30% on average compared with the surface system and its wet and dry performance has increased by about 1.4 and 1.7 times, respectively. Therefore, water use efficiency for maize plant in wick irrigation method increased by 2.5 times compared with surface method. The results show the effectiveness of wick irrigation method on yield and water use efficiency for corn cultivation in semi-arid areas compared with surface-furrow irrigation method

Investigating the Effect of Using Iranian Zeolite and Bentonite in Desalination

Global water demand is constantly increasing, while freshwater resources are limited due to increased demand and the effects of climate change, especially in arid and semi-arid regions such as Iran. The cost of water production is one of the most important factors in choosing a desalination method. In the adsorption method using natural materials, the cost of desalination can be reduced. In this study, Iranian zeolite and bentonite were used to reduce salinity by batch test. The adsorbents were identified by EDx, XRD, and BET. Clays were also modified with 1 M hydrochloric acid. The results showed that Iranian zeolite and bentonite used in this study as mineral adsorbents do not have the efficiency to reduce salinity and increase the electrical conductivity and sodium content of water. The highest increase in sodium concentration in samples was related to natural bentonite (102.5 mg/g) at the highest salinity concentration (64000 mg/L) and the lowest increase in sodium concentration was related to natural zeolite at 0.066 mg/g in the lowest salinity concentration (640 mg/L). Also, the highest increase in electrical conductivity was related to natural bentonite with an increase of 4.3 dS/m. It is noteworthy that after acid correction, the amount of electrical conductivity increased significantly in both clays. Therefore, due to the differences between the clays, it is better to first examine them in terms of construction and then use them in the field of desalination

Effect of clay type and clay content on moisture content and bulk soil electrical conductivity as measured using time domain reflectometry

Time domain reflectometry (TDR) is becoming a widely used method to determine volumetric soil water content ($theta$) and bulk soil electrical conductivity (EC$sb{ rm a}$). It has been found that the $theta$ and EC$sb{ rm a}$ values obtained by this method, on certain soils, require calibration. The purpose of this study was to monitor the effects of soil texture (most particularly the clay type and clay content) on $theta$ and EC$sb{ rm a}$ estimated by TDR.Water content was measured, gravimetrically and by TDR, on packed columns of nine soil mixtures, composed of three clay types (Hydrite, Bentonite, and Ste. Rosalie clay) and coarse sand at three levels (8, 16, and 30% by weight) of these clay materials. Three replicates of each mixture (a total of 27 columns) were made to statistically establish the effect of the clay type and the clay content on $theta$ and EC$sb{ rm a}$ readings by TDR. It was found that the TDR overestimated $theta$ for the Hydrite and Ste. Rosalie (Natural) materials but accurately predicted for the Bentonite materials, compared to gravimetric determinations.Bulk soil electrical conductivity was simultaneously measured by two independent techniques, TDR and 4-probe, on the same soils. It was found that the clay types and clay contents have almost equal effects on the EC$sb{ rm a}$ as measured by TDR and 4-probe techniques. It was found that the estimated EC$sb{ rm a}$ values obtained by TDR and 4-probe methods for the fine-textured Bentonite materials were lower than those for the Hydrite and Ste. Rosalie materials at equal $theta$ and EC$sb{ rm W}$ (electrical conductivity of soil water)

Use of soil and vegetative filter strips for reducing pesticide and nitrate pollution

The use of agricultural chemicals often results in water pollution. This research, comprising three parts, was designed to investigate the role of soil and grass strips and water table management in reducing pesticide and nitrate residues in drainage waters.The first part of the research was made on lysimeters to investigate the effects of soil and grass cover under two water table management regimes. Four treatments were involved: subsurface drainage, controlled drainage, grass cover, and bare soil. Each treatment consisted of three replicates. Contaminated water containing atrazine, metolachlor, and metribuzin residues was applied to the lysimeters and samples of drain effluent were collected. Significant reductions in pesticide concentrations were found in all treatments.In the first year (1993), herbicide levels were reduced significantly, from an average of 250 mug/L to less than 10 mug/L. In the second year (1995), water polluted at a concentration of 50 mug/L, was applied to the lysimeters, and herbicide residues were reduced significantly to less than 1 mug/L. Subsurface drainage and grass cover lysimeters (SDG treatment) reduced herbicide concentration levels to a greater extent than the other treatments and the controlled drainage lysimeters reduced nitrate concentration levels to a greater extent than the free drainage lysimeters.The second part of the research was a field study that reports the development and testing of an on-farm pollution control system using soil as a biological filter for trapping herbicide residues. A field site with four shallow surface ditches, underlain with four perforated drain pipes, was used to carry-out field measurements. Polluted water with concentration levels of 30 mg/L of nitrate and 100 mug/L of three commonly-used herbicides was applied to the ditches for 10 days continuously; and no water was applied for the following ten days. This cycle was repeated three times. Water samples were collected both before application and after the water came out of the drains. Herbicide levels were reduced significantly in drainage waters. The average concentration level of nitrate in drainage water was found to be 17 mg/L in comparison to 30 mg/L in applied water. Also, the bio-degradation of herbicide residues in the soil was found to occur between water applications. Thus, it appears that the system would be self-sustainable in the long term.The third part of the research utilizes a water table model, DRAINMOD, for simulating drainage waters from agricultural land and a solute transport model, PRZM2, for simulating pesticide concentrations in the drain effluent coming out of the grass filter area. DRAINMOD was used to estimate the daily drain outflows that would occur in a 100 ha subsurface drained field in the for a 1-in-20 year annual rainfall period. It was found that 6% of the farm area could be used to bring down the concentrations in drainage water from 50 mug/L to less than 1 mug/L for the three herbicides. (Abstract shortened by UMI.

Distribución y pérdidas de agua y nitrato bajo fertirriego por surcos alterno y convencional

16 Pags., 4 Tabls., 11 Figs.Alternate furrow irrigation and surface fertigation have been known as techniques to control water and fertilizer losses. The main goal of this field study was to characterize the combined effect of these techniques on water and nitrate losses and on soil water and nitrate concentration. Two types of alternate furrow irrigation, i.e., variable alternate furrow irrigation (AFI) and fixed alternate furrow irrigation (FFI), as well as conventional furrow irrigation (CFI) were considered in the experiments. Results evidenced higher infiltration at irrigated furrows under AFI and FFI as compared to CFI. Increased lateral water movement under alternate irrigation resulted in lower water and nitrate losses via runoff and deep percolation. Water application efficiency for the CFI, FFI and AFI strategies amounted to 61.3%, 71.8% and 77.0% in the first fertigation and 36.4%, 58.8% and 60.7% in the second fertigation, respectively. Nitrate runoff for the CFI, FFI and AFI strategies amounted to 32.4%, 31.2% and 25.7% in the first fertigation and 44.3%, 35.1% and 32.7% in the second fertigation, respectively. Soil water content and nitrate concentration at the upstream part of the experimental field were larger than at the middle and downstream parts for all three irrigation regimes. Overall, alternate furrow fertigation, particularly AFI, stands as a simple and practical management practice for water and fertilizer conservation in agricultural fields.This research was funded by The Center of Excellence for Evaluation and Rehabilitation of Irrigation and Drainage Networks in the University of Tehran.Peer reviewe

A study of columns to reduce mineral and biological pollutants during recharge operation by treated municipal wastewater

© 2015 Balaban Desalination Publications. All rights reserved. One of the most important methods for reusing treated wastewater is soil aquifer treatment (SAT). For simulation of SAT pounds, three columns of 30 cm in diameter and 250 cm in height were filled with sandy loam soil and used to assess the removal of chemical and biochemical oxygen demands (COD and BOD), nitrogen, phosphate, total dissolved solid, total coliform, and fecal coliform from treated wastewater. The soil surfaces of columns were covered by different materials; one by geotextile, another by coarse structural debris, and the third one remained bare. These columns were saturated by treated wastewater from Mahdasht–Karaj treatment plant. All of the experiments were conducted under permanent saturated soil condition. The removal percentages of geotextile soil column were 84.7, 77, 67.7, 99.5, 99.7, and 79.9 for BOD, COD, TSS, coliform, fecal coliform, and phosphate, respectively, and low efficiency for nitrate removal in all columns. Also it was observed that more waterlogging time leads to a decrease in pollutant removal. Using geotextile and structural debris as soil surface covers will lead to a reduction in pollutants transfer and help in stabilizing the soil system as a filter

Simulation of 1D surface and 2D subsurface water flow and nitrate transport in alternate and conventional furrow fertigation

48 Pags., 3 Tabls., 11 Figs. The definitive version is available at: http://link.springer.com/journal/271Increasing water and fertilizer productivity stands as a relevant challenge for sustainable agriculture. Alternate furrow irrigation and surface fertigation have long been identified as water and fertilizer conserving techniques in agricultural lands. The objective of this study was to simulate water flow and fertilizer transport in the soil surface and in the soil profile for variable and fixed alternate furrow fertigation and for conventional furrow fertigation. An experimental data set was used to calibrate and validate two simulation models: a 1D surface fertigation model and the 2D subsurface water and solute transfer model HYDRUS-2D. Both models were combined to simulate the fertigation process in furrow irrigation. The surface fertigation model could successfully simulate runoff discharge and nitrate concentration for all irrigation treatments. Six soil hydraulic and solute transport parameters were inversely estimated using the Levenberg–Marquardt optimization technique. The outcome of this process calibrated HYDRUS-2D to the observed field data. HYDRUS-2D was run in validation mode, simulating water content and nitrate concentration in the soil profiles of the wet furrows, ridges and dry furrows at the upstream, middle and downstream parts of the experimental field. This model produced adequate agreement between measured and predicted soil water content and nitrate concentration. The combined model stands as a valuable tool to better design and manage fertigation in alternate and conventional furrow irrigation.This research was funded by The Center of Excellence for Evaluation and Rehabilitation of Irrigation and Drainage Networks of the University of Tehran.Peer reviewe

An experimental data set for alternate and continuous furrow fertigation: water and nitrate transfer [Dataset]

1 File .xls with data (AltFurFer.xls). Related publications: Ebrahimian, H., Liaghat, A., Parsinejad, M., and Playán, E. 2012. Distribution and loss of water and nitrate under alternate and conventional furrow fertigation. Spanish Journal of Agricultural Research, In press; Ebrahimian, H., Liaghat, A., Parsinejad, M., Playán, E., Abbasi, F. and Navabian M. 2012. Simulation of 1D surface and 2D subsurface water flow and nitrate transport in alternate and conventional furrow fertigation. Irrigation Science, In press.This data set contains the results of the experimental evaluation of two alternate and conventional furrow fertigation events. Experiments were performed at the College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran. Three irrigation treatments were considered: Variable Alternate Furrow Irrigation (AFI), Fixed Alternate Furrow Irrigation (FFI) and Conventional Furrow Irrigation (CFI). Liquid fertilizer was injected in the irrigation water during part or the irrigation event. The data set contains advance and recession, soil water and nitrate, inflow and outflow discharge and nitrate concentration, and meteorological data.Peer reviewe

Managing controlled drainage in irrigated farmers’ fields : A case study in the Moghan plain, Iran

Conventional free subsurface drainage practices in the Moghan Plan, in northwest Iran, result in low irrigation efficiency and excessive volumes of drainage water causing extensive environmental problems. Controlled drainage (CD) is promoted to boost crop yields and reduce subsurface drainage flows and leaching of nutrients. This study was conducted to test management options for CD in irrigated farmers’ fields in the Moghan plain. Three options were tested: subsurface drains at 2 m with free outflow (FD), controlled drainage at 70 cm below soil surface (CD70) and controlled drainage with a varying depth depending on the crop stage (CDch). Irrigation gifts were based on the daily measured soil water content and thus varied per drainage treatment. In winter, wheat and barley were grown followed by maize in summer. For each crop and treatment, three replicates were made. The highest crop yields (for all crops) were found with CDch, followed by CD70. For wheat, the yields were respectively 27% and 41% higher in the CD70 and CDch compared to FD. For barley these increase was respectively 23% (CD70) and 34% (CDch) and for maize (forage yields) 19% (CD70) and 25% (CDch). The same trends were observed in water use efficiencies (WUE): compared to FD, the WUE was 26% in CD70 and 40% higher in CDch; for barley these increases were respectively 19% (CD70) and 32% (CDch), and for maize (forage yields) 30% (CD70) and 44% (CDch). Controlled drainage not only reduced subsurface drainage rates, but also nitrate and phosphorous losses. The average drain discharges with CDch were respectively 33%, 45% and 44% lower than FD for wheat, barley and maize. Flow-weighted NO3 concentration in drainage discharge of CD70 and CDch were, respectively, 15% and 9% for wheat, 9% and 13% for barley, and 8% and 7% for maize lower than in FD. Soil salinity decreased in FD, but slightly increased in the CD treatments. Thus, although controlled drainage clearly has advantages above free drainage practices, to optimize CD management options, more research is needed on the long-term effects of controlled drainage on soil salinity.</p