Irrigation Scheduling Program Research Articles

Improving parameterization of an evapotranspiration estimation model with eddy covariance measurements for a regional irrigation scheduling program

Actual evapotranspiration (ETa) is an essential variable in linking energy cycles, carbon, and water, yet challenging to measure. Inputs uncertainty and deficiencies in the key elements of hydrologic models are fundamental challenges for optimizing model performance. Furthermore, the performance of land surface model-based ETa, reanalysis, and remote sensing products varies with spatiotemporal scales. Here, we evaluate sources of bias in the regional Wisconsin Irrigation and Scheduling Program (WISP) model and develop a correction using eddy covariance (EC) observations. ETa, observations were made for five years (2018–2022) using EC systems in agricultural fields in Wisconsin. WISP model ETa bias was linked to underestimation of net longwave radiation (LWnet) that was traced to incorrect specification of effective clear sky atmospheric emissivity (εa,clr). Applying a correction to the εa,clr led to reduced WISP model percent bias (pbias) and error for both LWnet and ETa. The calibrated model more accurately represented observed ETa. The results indicate that explicit treatment of the LWnet balance decreases the uncertainty of model parameters and improves the WISP model performance at independent sites. Applying this improved model parameterization reduced the bias of LWnet radiation from 62.8% to -6.2%, which improved the Nash-Sutcliffe Efficiency (NSE) from -0.08 to 0.52 for ETa on training sites. Additionally, overall pbias was significantly reduced (p = 0.035) for validation sites after WISP correction. Hence, WISP performance improved for different crop types when optimal regional parameters were used, confirming the physical parameters' reliability. Our results highlight that model development should focus on energy balance parameterizations to improve ET simulation and the accuracy of hydrologic and climatic simulations for understanding critical processes underlying hydrologic and climatic variability and change over land.

Scheduling of Leaching Requirements to Prevent the Secondary Salinisation in the Root Zone

Leaching scheduling techniques are one of the suggested solutions for water scarcity problems .The aim of the study is to show the possibility of using leaching scheduling, when applying the irrigation scheduling program for a certain irrigation project, which was prepare by Water Resources Engineering –University of Baghdad with some modifications to generalized it and it make applicable to various climatic zone and different soil types.The objectives of this research is to build a system that concerns the prediction of the leaching scheduling (depth and date of leaching water), illustrating the main problems (soil salinity, save the amount of leaching requirement, and to maintain crops growth).The other objective is to compare between the calculated amount of leaching water with the amount of water that is suggested by designers. The program includes, the calculating of predicted daily soil salinity ,the depth of leaching water that should be applied to remove the salt from the soil when it reaches a harmful level, and the total annual volume of leaching water. The results showed, that the use of predicted leaching scheduling with its applicable constrains require high attention when choosing the cropping pattern for each climate zone. Also, it was found that the leaching program is a useful tool for saving irrigation water if cropping pattern has been adapted carefully. This means the leaching water depth should be added only when needed, and may not be necessary with each irrigation event.

Irrigation Scheduling Effect on Water Requirements

Irrigation scheduling techniques is one of the suggested solutions for water scarcity problem. The study aims to show the possibility of using practical and applicable irrigation scheduling program which was designed by Water Resources Department at the University of Baghdad by using Spreadsheet Formulas for Microsoft Excel program, version 2007, with some modification to generalize it and made it applicable to various climatic zone and different soil types, as a salvation for the shortage of irrigation water inside the irrigation projects. Irrigation projects which incidence of Tigris River basin will be taken as an applicable example. This program was based on water budgeting and programmed depending on scientific concepts which facilitate irrigation structures operation and ease the use by farmers. By using the abilities of this program, the monthly and annually water requirements and drainage water were estimated. Finally a comparison is made between the calculated discharges with the designers suggested ones. This comparisons showed that the use of this type of irrigation scheduling (i.e. predicted irrigation scheduling) with itsapplicable constrains require high attention when choosing the cropping pattern for each climate zone. Also it found that this irrigation program is a useful tool for saving water if cropping pattern has been chosen carefully.

Development of a soil moisture sensor‐based irrigation scheduling program for the midsouthern United States

AbstractThere is limited adoption of irrigation scheduling tools that could improve application timing and water use efficiency in row‐crop production systems common to the mid‐southern United States. The objectives of this manuscript are to describe a sensor‐based irrigation scheduling method and review its effects on water applied and crop productivity. The effects of scheduling irrigation based on the recommended construction, deployment, and utilization of the WATERMARK 200SS granular matrix (WATERMARK) sensor on water applied, crop productivity, and crop water use efficiency were reviewed for corn (Zea mays L.), soybean [Glycine max L. (Merr.)], peanut (Arachis hypogaea L.), and cotton (Gossypium hirsutum L.) produced in the Prairie region of Arkansas and the Delta regions of Arkansas and Mississippi. For corn and soybean, on‐farm research indicates the recommended irrigation threshold of −85 to −100 cbar reduces total water applied up to 40% while maintaining or improving yield up to 3%, net returns up to $39 acre−1, and irrigation water use efficiency up to 51% for soil textures ranging from very fine sandy loam to clay. Similarly, for peanut and cotton, results indicate the irrigation threshold that minimizes water use while maximizing yield and net returns is −50 cbar and −100 cbar, respectively. The recommended method for scheduling irrigations with a WATERMARK 200SS soil moisture sensor promotes the efficient use of water in row‐crop production systems common to the mid‐southern USA.

Irrigation scheduling strategies for pepper based on evaporation and reference evapotranspiration

The experiment with drip irrigated pepper was conducted at the Rimski Šančevi experimental field of the Institute of Field and Vegetable Crops in Novi Sad in 2019. The irrigation was scheduled on the basis of the water balance method. Two methods were used to compute the daily evapotranspiration of pepper (ETd): reference evapotranspiration (ETo) and evaporation from an open water surface (Eo). Crop coefficients (kc) and corrective coefficients (k) were used to convert ETo and Eo values into ETd. Kc and k were 0.3-0.4, 0.6-0.7, 0.9-1.1, 0.8-0.9 and 0.4, 0.7, 1.0 and 0.8 for initial stage, crop development, mid season, and late season, respectively. ETo was calculated by the Hargreaves equation. Eo values were measured by a Class-A pan located at a meteorological station near the experimental plot. Irrigation started when readily available water (RAW) in the 0.3 m soil layer was completely absorbed by plants. Differences in crop yield (Y) and irrigation water use efficiency (IWUE) obtained using Eo (42.58 t ha-1, 15.20 kg m-3) and ETo (40.78 t ha-1, 14.56 kg m-3) were not statistically different. Evapotranspiration rate was 364.2 mm and 337.3 mm in Eo and ETo variant, respectively. The fact that the differences in Y and IWUE between different calculations of ETd were not statistically significant indicates that both methods can be recommended for irrigation scheduling programs for pepper in the climatic conditions of the Vojvodina region. However, priority should be given to ETo due to the easy accessibility and reliability of data.

Periodic Versus Real-time Adjustment of a Leaching Fraction-based Microirrigation Schedule for Container-grown Plants

Two experiments were conducted to determine if a leaching fraction (LF)-guided irrigation practice with fixed irrigation run times between LF tests (LF_FX) could be improved by making additional adjustments to irrigation run times based on real-time weather information, including rain, using an evapotranspiration-based irrigation scheduling program for container production (LF_ET). The effect of the two irrigation practices on plant growth and water use was tested at three target LF values (10%, 20%, and 40%). For both Viburnum odoratissimum (Expt. 1) and Podocarpus macrophyllus (Expt. 2) grown in 36-cm-diameter containers with spray-stake microirrigation, the change in plant size was unaffected by irrigation treatments. LF_ET reduced water use by 10% compared with LF_FX in Expt. 2 but had no effect (P < 0.05) on water use in Expt. 1. Decreasing the target LF from 40% to 20% reduced water use 28% in both experiments and this effect was similar for both irrigation practices. For the irrigation system and irrigation schedule used in these experiments, we concluded that an LF-guided irrigation schedule with a target LF of 10% resulted in plant growth similar to one with a target LF of 40% and that the addition of a real-time weather adjustment to irrigation run times provided little or no improvement in water conservation compared with a periodic adjustment based solely on LF testing.

Production of Thuja (T. standishii x T. plicata) Using an Automated Micro-Irrigation System and Routine Leaching Fraction Testing in a Container Nursery1

Abstract A web-based, container irrigation scheduling program (CIRRIG) based on routine Leaching Fraction (LF=drainage/applied) testing and real-time weather monitoring was evaluated for its effect on plant growth and water use of Thuja (T. standishii x T. plicata) ‘Green Giant' in #15 [43 cm (17 inch)] containers in a commercial nursery in Florida. Independently-controlled irrigation zones each containing 830 plants were irrigated automatically with CIRRIG or with the nursery's traditional irrigation practice of a fixed daily rate. After 6 months, CIRRIG reduced the total volume of water applied by 51% [490 vs. 990 L/plant (129 vs. 262 gal/plant) but reduced growth in plant height and width by 15% and 10%, respectively. Routine LF testing indicated that the target LF of 25% was likely too low for the coarse pine bark substrate and spray-stake irrigation system. In light of stricter consumptive use permitting of water by governmental agencies, technologies such as CIRRIG may allow nurseries to produce more plants with less water. Index words: CIRRIG, evapotranspiration, growth, landscape plant, programmable logic controller, water use Species used in this study: Thuja Green Giant [Thuja (T. standishii x T. plicata) ‘Green Giant']

Evaluation the Use of Electronic Wireless Tensiometers in the Irrigation of Main Crops in Abu Dhabi

Two obstacles are associated with most of Abu Dhabi efforts to deal with the water shortage to sustain its agricultural sector. These problems are unskilled labors and lack of accurate crop water requirements data. Accurate information on crop water requirements is needed to help farmers improve their irrigation practices by better matching irrigation supply to crop water demand. A wireless capacitive sensor was evaluated in the irrigation of greenhouse tomato and cucumber in order to develop irrigation scheduling program. Amount of irrigation, yield, and water use efficiency were used to compare between the capacitive sensor system and three other irrigation orders obtained from FAO Penman-Monteith method to calculate the potential evapotranspiration as climate-based irrigation treatments (125%, 100%, and 75%). The results showed that the capacitive sensor gave accurate irrigation amount and t had the best yield. In addition, the data of this system helped in the development of a suitable irrigation scheduling program for the two crops. Such a smart irrigation system is a promising tool to be implemented in the regions that suffer from water shortage.

Response of Wheat Yield to Irrigation Scheduling Program under Egyptian Sandy Soil Conditions

Response of Wheat Yield to Irrigation Scheduling Program under Egyptian Sandy Soil Conditions

Evaluation of Irrigation Scheduling Program and Wheat Yield Response in Egyptian Sandy Soil Conditions

Two field experiments were performed in EL-Busily region, EL-Behira governorate under the condition of sandy soil during 2009/2010 and 2010/2011 seasons, to study the impact of three amount of water irrigation 60, 70 and 90% from evapotranspiration rate (1216 m3) and three compost rates (2, 4 and 6 ton/fed.) on some growth, yield and its components of two wheat varieties (sakha 93 and Gemmeiza 9). In both of seasons, the treatments were arranged in split split design in three replicates. Results of the two seasons showed that, by increasing the water irrigation amount from 60 to 70 or 90% of the evapotranspiration (1216 m3) that led to gradually significant increases for (leaf area (cm2)/plant, dry weight (gm)/plant) and yield and yield components (No. spikes/ m2, weight of grains /spike, No of grains/spike, weight of 1000 grains, economic yield (kg/fed) and harvest index). Compost rates had significant impacts on previous characteristics, during the two experimental seasons. The best compost rate was (6 ton/fed) which gave the best results for these traits. As compared with the lowest rate of 2 ton/fed. Results revealed that, Gemmieza 9 wheat variety exiled sakha 93 wheat variety significantly for above mentioned measurements during the two seasons. As for the first and second order interactions between the tested factors, results in the two trial seasons showed that, most of the interactions had significant effects on that character. It wealthy mentions that significant interaction effect was found between water irrigation amount with compost rates and wheat varieties was found during the two seasons. The highest values for previous characters were obtained by sowing Gemmieza-9 with adding irrigation quantity of 90% from evapotranspiration and practicing 6 ton compost per Fadden.

Productivity of Onions Using Subsurface Drip Irrigation versus Furrow Irrigation Systems with an Internet Based Irrigation Scheduling Program

Selection of the proper irrigation method will be advantageous to manage limited water supplies and increase crop profitability. The overall objective of this study was to evaluate the effect of subsurface drip irrigation (SDI) and furrow irrigation on onion yield and irrigation use efficiency. This study was conducted in two locations, a commercial field and a field located at the Texas A&M AgriLife Research Center in Weslaco, TX. This study was conducted as a split-plot design for both sites with two treatments (SDI and furrow irrigation) and three replications per treatment. The total onion yield obtained with the SDI systems was more than 93% higher than the yield obtained with furrow irrigation systems. The large onion size was 181% higher for the SDI system than the furrow system in both sites. The colossal size yield was also higher. At one site colossal yield was 206% higher than furrow, while at another site furrow yielded no colossal onions and SDI had some production. It was concluded that drip irrigation systems more than double yields and increased onion size while using almost half of the water. This was due to SDI allowing for more frequent and smaller irrigation depths with higher irrigation efficiency than furrow irrigation systems.

LANDSCAPE COEFFICIENT TO DETERMINE WATER REQUIREMENT FOR A COMPUTER MODEL

The two factors used to determine landscape water requirement (ETL), the landscape coefficient and reference evapotranspiration, are solely responsible for producing differences in water loss estimates. For plantings in the same location (i.e., where the same ETo values will be used), the differences will arise solely from the landscape coefficient. To produce useful estimates of water loss, therefore, it is important to carefully determine the value of KL. In agriculture, irrigation water requirements are well established for many crops. In urban landscapes, irrigation requirements have been determined for turf grasses, but not for most landscape species. This study adapts this method for application to landscape plantings. The method used for estimating water needs for landscape plantings is basically the same as that used for crops and turfgrasses. One key change, however, has been made: instead of using the crop coefficient (Kc), a landscape coefficient (KL) has been substituted. The main objective of this work is building computer program to determine water requirement for some multi-plant landscape and modern system for their irrigation. Audit in the accounts of landscape coefficient (KL) closest to the prevailing conditions by application Landscape Irrigation Scheduling program outputs, led to save water use by 60% for landscape plants in Giza (latitude 30o 05', longitude 31o12') with good appearance and growth for landscape plants and grass. The program could offer a simple tool for planning ornamental plants and turf grass water requirements for landscape projects.

Decision support for agricultural water management

Irrigation water use is the major pressure limiting the availability of fresh water resources in the Mediterranean. Efficient irrigation scheduling programs (IRSPs) are able to reduce water consumption; however, their selection and placement in large agricultural landscapes depend on location specific characteristics and economic indicators. Towards this end, a novel and efficient Decision Support Tool (DST) is developed in MATLAB-programming, able to assess the effectiveness of different IRSPs in reducing total agricultural water use at the catchment scale along with their impact on crop yields. The DST integrates a look-up table with data on irrigation water amounts and crop yields at different locations within a catchment, populated by a hydrological and crop growth estimator: the process-based SWAT model, into a multi-objective Genetic Algorithm, which serves as the optimization engine for the allocation of measures across the agricultural land. The optimization scheme leads rapidly to the optimal trade-off frontier between the conflicting objectives providing spatial allocations of IRSPs. The tool was implemented in the Ali Efenti catchment demonstrating optimal solutions that could save more than 10% of water by reducing cotton yields less than 5% from the baseline. The study highlights the potential of the tool to assist in the development of cost-effective water saving plans at the catchment level in order to reduce the risk of desertification in intensively cultivated areas.

Efficient registration of optical and IR images for automatic plant water stress assessment

Automatic registration of optical and IR images is a crucial step towards constructing an automated irrigation control system where plant water information is sensed via thermal imaging. The scene of the IR image is assumed to be completely included in the optical image and the alignment between the common scene in the two images may involve translation and rotation by a small angle, though a small scale difference may also be present. This automatic registration of data from two quite different, non-rigid imaging regimes presents several challenges, which cannot be overcome using common image processing techniques. In this paper, a fully automatic image registration algorithm for the alignment of optical and IR image pairs is described, where Pearson's cross-correlation between a pair of images serves as the similarity measure. A computationally efficient algorithm is designed and packaged as a software application. This work provides an intervention free process for extracting plant water stress information which can be fed into an automated irrigation scheduling program. The proposed algorithm is justified by the comparison of its registration performance with that of other potential algorithm techniques using several experimental data collections. Our results demonstrate the effectiveness of the proposed algorithm and efficiency of its application to the registration of IR and optical images.

The effect of irrigation scheduling and water stress on the maturity and chemical composition of Virginia tobacco leaf

The study was carried out in order to determine the effect of different irrigation scheduling programs and water stress, imposed at different growth stages, on the maturity and leaf chemistry of Virginia tobacco ( Nicotiana tabacum L.). Field experiments and lab investigations were carried out during 2000–2003, on a silty loam Entisol soil, poor in organic matter and rich in potassium, on the fields of Atatürk Soil and Water Resources Research Institute in Kirklareli, Turkey. A randomized complete block experimental design with three replications was applied, and K-326 Virginia tobacco cultivar was used in the experiment. Three known stages of the plant – vegetative (V), yield formation (F), and ripening (R) – were considered, and a total of 14 irrigation treatments (including rain-fed) were applied. All the experimental treatments were irrigated on the same day of VFR and were irrigated at each growth stage with the amount of water required to fill the 0–90 cm soil depth to field capacity; and three levels of water reductions (0%, 40% and 60%) were done at each development stage. Results of the investigations show that irrigation scheduling and the water stress imposed during different stages of growth influenced the ripening dynamics of Virginia tobacco leaves and that severe water stress causes delay in the ripening of the leaves. Favorable moisture conditions considerably decrease the nicotine and nitrogen content of the Virginia tobacco leaves, both of which are hazardous for humans, to the ranges of 0.85–1.21% versus 2.1–2.2% under stress (for nicotine), and 1.4–1.6% versus 1.8–2.0%, and 2.0–2.4% versus 2.9–3.1% (for nitrogen) for 2001 and 2003, respectively. However the percentage of chloride and sodium in the leaf increases if the amount of seasonal water is increased. It was determined also that close linear relationships exist between seasonal irrigation water amounts or seasonal evapotranspiration and any of the chemical traits. Mutual relationships between nicotine and each of the traits – i.e. nitrogen, chloride, potassium, and sodium – were also established.

Estimating cotton evapotranspiration crop coefficients with a multispectral vegetation index

Crop coefficients are a widely used and universally accepted method for estimating the crop evapotranspiration (ETc) component in irrigation scheduling programs. However, uncertainties of generalized basal crop coefficient (Kcb) curves can contribute to ETc estimates that are substantially different from actual ETc. Limited research with corn has shown improvements to irrigation scheduling due to better water-use estimation and more appropriate timing of irrigations when Kcb estimates derived from remotely sensed multispectral vegetation indices (VIs) were incorporated into irrigation-scheduling algorithms. The purpose of this article was to develop and evaluate a Kcb estimation model based on observations of the normalized difference vegetation index (NDVI) for a full-season cotton grown in the desert southwestern USA. The Kcb data used in developing the relationship with NDVI were derived from back-calculations of the FAO-56 dual crop coefficient procedures using field data obtained during two cotton experiments conducted during 1990 and 1991 at a site in central Arizona. The estimation model consisted of two regression relations: a linear function of Kcb versus NDVI (r2=0.97, n=68) used to estimate Kcb from early vegetative growth to effective full cover, and a multiple regression of Kcb as a function of NDVI and cumulative growing-degree-days (GDD) (r2=0.82, n=64) used to estimate Kcb after effective full cover was attained. The NDVI for cotton at effective full cover was ~0.80; this value was used to mark the point at which the model transferred from the linear to the multiple regression function. An initial evaluation of the performance of the model was made by incorporating Kcb estimates, based on NDVI measurements and the developed regression functions, within the FAO-56 dual procedures and comparing the estimated ETc with field observations from two cotton plots collected during an experiment in central Arizona in 1998. Preliminary results indicate that the ETc based on the NDVI-Kcb model provided close estimates of actual ETc.

Avaliação do manejo de irrigação no Perímetro Irrigado de Pirapora, MG

Com o presente trabalho, objetivou-se avaliar o manejo de irrigação no Perímetro Irrigado de Pirapora, MG, durante o período de 1999 a 2000. A demanda de irrigação foi simulada utilizando-se o balanço de água no solo para todo o perímetro irrigado e considerando-se as especificidades de cada lote. Os resultados dos volumes de água, obtidos por meio das simulações, foram integralizados mensalmente e comparados com os volumes de água medidos nos hidrômetros de cada lote. Os resultados obtidos permitiram concluir-se que: ocorreu uma aplicação excessiva de água em todo o perímetro, com exceção dos meses de janeiro de 1999 e janeiro, fevereiro, março e abril de 2000, quando a irrigação foi deficiente. Portanto, é necessária a implantação de um plano de manejo de irrigação que vise à otimização do uso de água no perímetro.

Cotton response to high frequency surface irrigation

High frequency irrigation with surface irrigation methods has been proposed as a means to increase cotton productivity in cases where drip irrigation or other pressurized systems are not economically justifiable. Field studies were conducted in 1993 and 1994 to evaluate the effects of surface irrigation frequency on the growth, lint yield and water use for a semi-determinate cotton cultivar in central Arizona. Cotton was grown in level basins on a sandy loam under three irrigation treatments defined as low frequency irrigation for the whole season (L), high frequency irrigation for the whole season (H), and low frequency irrigation until the initiation of rapid fruiting, high frequency during rapid fruiting, and low frequency after rapid fruiting (LHL). The treatments were governed by the percentage of allowable soil water depletion within the effective root zone, and the allowable depletion targets for low and high frequency irrigation were 55 and 30%, respectively. An irrigation scheduling program calculated the soil water depletion within the estimated cotton root depth on a daily basis for each treatment and was used to project the dates and amounts for treatment irrigations. In 1993, seven, 14, and 11 irrigations and in 1994 eight, 13 and 10 irrigations were given to the L, H, and LHL treatments, respectively. The total amount of water applied including rainfall differed among the treatments by 4% in 1993 and by 1% in 1994. Soil water measurements indicated that actual soil water depletion within the estimated cotton root depth immediately before treatment irrigations was close to the intended treatment allowable depletion targets for the majority of the growing season. Cotton growth and lint yields were maximized under the H treatment, and yields in this treatment averaged 15 and 21% more lint than the L treatment for the first and second seasons, respectively. The LHL treatment, although not as effective in increasing crop productivity as the H treatment, out yielded the low frequency treatment by an average of 10% in the two seasons. Crop evapotranspiration determined from the soil water balance was 8 and 9% higher for the H than the L treatment and 3 and 5% higher for the LHL than the L treatment in 1993 and 1994, respectively.

Model validation and crop coefficients for irrigation scheduling in the North China plain

ISAREG is a model for simulation and evaluation of irrigation scheduling. The model performs the soil water balance and evaluates impacts of water stress on yields for different crops. It is now being used to support a water saving irrigation scheduling program in a pilot area in the North China plain. This paper reports on the calibration and validation of the model using independent data sets relative to winter wheat and summer maize. Data are originated from the Wangdu experimental station and concern a set of drainage lysimeters where diverse irrigation treatments were applied representing different strategies of deficit irrigation. The calibration of the model was performed by deriving the crop coefficients adapted to the local climatic conditions, and considering the soil freezing during winter. The validation of the model was performed using different data sets. Results show that the relative errors to estimate the soil water content averaged 5.3% for summer maize and 7.3% for the winter wheat. These results support the use of the model in the practice.

Evaluation of irrigation scheduling program and spring wheat yield response in southwestern Colorado

Effective irrigation scheduling to manage water for spring wheat ( Triticum aestivum L.) in southwestern Colorado was investigated under variable water applications. This study was conducted (1) to determine the effects of varying rates of water replacement (0ET, 0.33ET, 0.67ET, 10ET, and 1.33ET) on spring wheat grain yield, dry matter yield, root water uptake, and water use efficiency, (2) to develop local crop coefficients, and (3) to evaluate the irrigation scheduling program called ‘SCHED’ that had been used in the area. Daily weather data was used to calculate reference ET using the Penman equation. Crop ET was predicted by using the irrigation scheduling program, ‘SCHED’. Both grain yield and dry matter increased significantly with the increase in water application rates, up to LOET application rate. Crop coefficients estimated at various water application rates were greater than the values used in the irrigation scheduling program. Total water use efficiency (TWUE) and irrigation water use efficiency (IWUE) for grain yield were considerably greater at 0.33ET than for other rates, whereas TWUE and IWUE for dry matter yield followed the order 0.33ET > LOET > 0.67ET > 1.33ET > 0ET.