scholarly journals A Novel ArcGIS Toolbox for Estimating Crop Water Demands by Integrating the Dual Crop Coefficient Approach with Multi-Satellite Imagery

Water ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 38 ◽  
Author(s):  
Juan Ramírez-Cuesta ◽  
José Mirás-Avalos ◽  
José Rubio-Asensio ◽  
Diego Intrigliolo
Keyword(s):  
Information And Communication Technologies ◽  
Mean Squared Error ◽  
Irrigation System ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Irrigation Season ◽  
Agricultural Field ◽  
Crop Water ◽  
Water Demands ◽  
Crop Coefficients

Advances in information and communication technologies facilitate the application of complex models for optimizing agricultural water management. This paper presents an easy-to-use tool for determining crop water demands using the dual crop coefficient approach and remote sensing imagery. The model was developed using Python as a programming language and integrated into an ArcGIS (geographic information system) toolbox. Inputs consist of images from satellites Landsat 7 and 8, and Sentinel 2A, along with data for defining crop, weather, soil type, and irrigation system. The tool produces a spatial distribution map of the crop evapotranspiration estimates, assuming no water stress, which allows quantifying the water demand and its variability within an agricultural field with a spatial resolution of either 10 m (for Sentinel) or 30 m (for Landsat). The model was validated by comparing the estimated basal crop coefficients (Kcb) of lettuce and peach during an irrigation season with those tabulated as a reference for these crops. Good agreements between Kcb derived from both methods were obtained with a root mean squared error ranging from 0.01 to 0.02 for both crops, although certain underestimations were observed resulting from the uneven crop development in the field (percent bias of −4.74% and −1.80% for lettuce and peach, respectively). The developed tool can be incorporated into commercial decision support systems for irrigation scheduling and other applications that account for the water balance in agro-ecosystems. This tool is freely available upon request to the corresponding author.

scholarly journals Evaluation of a Hybrid Reflectance-Based Crop Coefficient and Energy Balance Evapotranspiration Model for Irrigation Management

2018 ◽  
Vol 61 (2) ◽  
pp. 533-548 ◽  
Author(s):  
J. Burdette Barker ◽  
Christopher M. U. Neale ◽  
Derek M. Heeren ◽  
Andrew E. Suyker
Keyword(s):  
Remote Sensing ◽  
Energy Balance ◽  
Water Balance ◽  
Real Time ◽  
Eddy Covariance ◽  
Irrigation Management ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Balance Model ◽  
Crop Coefficients

Abstract. Accurate generation of spatial soil water maps is useful for many types of irrigation management. A hybrid remote sensing evapotranspiration (ET) model combining reflectance-based basal crop coefficients (Kcbrf) and a two-source energy balance (TSEB) model was modified and validated for use in real-time irrigation management. We modeled spatial ET for maize and soybean fields in eastern Nebraska for the 2011-2013 growing seasons. We used Landsat 5, 7, and 8 imagery as remote sensing inputs. In the TSEB, we used the Priestly-Taylor (PT) approximation for canopy latent heat flux, as in the original model formulations. We also used the Penman-Monteith (PM) approximation for comparison. We compared energy balance fluxes and computed ET with measurements from three eddy covariance systems within the study area. Net radiation was underestimated by the model when data from a local weather station were used as input, with mean bias error (MBE) of -33.8 to -40.9 W m-2. The measured incident solar radiation appeared to be biased low. The net radiation model performed more satisfactorily when data from the eddy covariance flux towers were input into the model, with MBE of 5.3 to 11.2 W m-2. We removed bias in the daily energy balance ET using a dimensionless multiplier that ranged from 0.89 to 0.99. The bias-corrected TSEB ET, using weather data from a local weather station and with local ground data in thermal infrared imagery corrections, had MBE = 0.09 mm d-1 (RMSE = 1.49 mm d-1) for PM and MBE = 0.04 mm d-1 (RMSE = 1.18 mm d-1) for PT. The hybrid model used statistical interpolation to combine the two ET estimates. We computed weighting factors for statistical interpolation to be 0.37 to 0.50 for the PM method and 0.56 to 0.64 for the PT method. Provisions were added to the model, including a real-time crop coefficient methodology, which allowed seasonal crop coefficients to be computed with relatively few remote sensing images. This methodology performed well when compared to basal crop coefficients computed using a full season of input imagery. Water balance ET compared favorably with the eddy covariance data after incorporating the TSEB ET. For a validation dataset, the magnitude of MBE decreased from -0.86 mm d-1 (RMSE = 1.37 mm d-1) for the Kcbrf alone to -0.45 mm d-1 (RMSE = 0.98 mm d-1) and -0.39 mm d-1 (RMSE = 0.95 mm d-1) with incorporation of the TSEB ET using the PM and PT methods, respectively. However, the magnitudes of MBE and RMSE were increased for a running average of daily computations in the full May-October periods. The hybrid model did not necessarily result in improved model performance. However, the water balance model is adaptable for real-time irrigation scheduling and may be combined with forecasted reference ET, although the low temporal frequency of satellite imagery is expected to be a challenge in real-time irrigation management. Keywords: Center-pivot irrigation, ET estimation methods, Evapotranspiration, Irrigation scheduling, Irrigation water balance, Model validation, Variable-rate irrigation.

scholarly journals Estimation of Crop Water Deficit in Lower Bari Doab, Pakistan Using Reflection-Based Crop Coefficient

2020 ◽  
Vol 9 (3) ◽  
pp. 173
Author(s):  
Muhammad Asif Javed ◽  
Sajid Rashid Ahmad ◽  
Wakas Karim Awan ◽  
Bilal Ahmed Munir
Keyword(s):  
Water Deficit ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Crop Coefficient ◽  
Maximum Temperature ◽  
Filter Method ◽  
Command Area ◽  
Landsat 8 ◽  
Crop Water ◽  
Crop Coefficients

There is a global realization in all governmental setups of the need to provoke the efficient appraisal of crop water budgeting in order to manage water resources efficiently. This study aims to use the satellite remote sensing techniques to determine the water deficit in the crop rich Lower Bari Doab Canal (LBDC) command area. Crop classification was performed using multi-temporal NDVI profiles of Landsat-8 imagery by distinguishing the crop cycles based on reflectance curves. The reflectance-based crop coefficients (Kc) were derived by linear regression between normalized difference vegetation index (NDVI) cycles of the Moderate Resolution Imaging Spectroradiometer (MODIS) MOD13Q1 and MYD13Q1 products and Food and Agriculture Organization (FAO) defined crop coefficients. A MODIS 250 m NDVI product of the last 10 years (2004-2013) was used to identify the best performing crop cycle using Fourier filter method. The meteorological parameters including rainfall and temperature substantiated the reference evapotranspiration (ET0) calculated using the Hargreaves method. The difference of potential ET and actual ET, derived from the reflectance-based Kc calculated using reference NDVI and current NDVI, generates the water deficit. Results depict the strong correlation between ET, temperature and rainfall, as the regions having maximum temperature resulted in high ET and low rainfall and vice versa. The derived Kc values were observed to be accurate when compared with the crop calendar. Results revealed maximum water deficit at middle stage of the crops, which were observed to be particularly higher at the tail of the canal command. Moreover, results also depicted that kharif (summer) crops suffer higher deficit in comparison to rabi (winter) crops due to higher ET demand caused by higher temperature. Results of the research can be utilized for rational allocation of canal supplies and guiding farmers towards usage of alternate sources to avoid crop water stress.

scholarly journals Estimativa da Evapotranspiração e dos Coeficientes de Cultura para Diferentes Fases de Desenvolvimento da Melancia (Evapotranspiration Estimate and Cultural Factors for Diferent Stages of Development of Watermelon)

2013 ◽  
Vol 6 (5) ◽  
pp. 1417 ◽  
Author(s):  
Antonio Ricardo Santos de Andrade ◽  
Adiel Felipe da Silva Cruz ◽  
Edson Carlos dos Santos Cavalcante ◽  
José Claudio Faustino de Albuquerque ◽  
Werônica Meira de Souza
Keyword(s):  
Irrigation System ◽  
Irrigation Management ◽  
Crop Coefficient ◽  
Main Element ◽  
Experimental Unit ◽  
Management Approach ◽  
Crop Evapotranspiration ◽  
Crop Development ◽  
Maximum Water ◽  
Crop Coefficients

A evapotranspiração constitui no principal elemento envolvido nas exigências hídricas das culturas, sua estimativa deve ser precisa, sendo utilizada no manejo da irrigação, como também na tomada de decisão que consiste em determinar se a cultura atende as condições edafoclimáticas da região. Um dos métodos de manejo da irrigação que se destaca por aproximar ao máximo a quantidade ideal de água a ser oferecida à cultura é a determinação da evapotranspiração da cultura (ETc). Sendo assim, o presente trabalho objetivou em estimar a evapotranspiração da cultura (ETc) e do coeficiente de cultura (Kc) para diferentes fases fenológicas na melancia. A variedade utilizada foi a Crimson Sweet, semeados no espaçamento de 1,5 m x 0,75 m onde o sistema de irrigação empregado foi por gotejamento. Para tanto, o experimento foi conduzido na área experimental da Unidade acadêmica de Garanhuns da UFRPE, no período de 01/02/2013 a 07/04/2013. O cálculo do Kc foi obtido pela relação entre ETc e ETo calculada pelo método do balanço hídrico do solo e estimada pelo método de tanque Classe A, respectivamente, no período de 01 até 66 dias após o plantio (DAP). A evapotranspiração média da cultura da melancia nos 66 dias do balanço foi de 11,36 mm dia-1 e os valores médios dos coeficientes de cultivo (Kc) obtidos pela relação entre ETc e ETo foram 1,80; 1,97; 1,84 e 1,60 para a fase vegetativa, floração, maturação e colheita, respectivamente, e o máximo consumo de água pela cultura deu-se no estádio de floração. A B S T R A C T Evapotranspiration is the main element involved in crop water requirements, your estimate should be accurate, by using management of irrigation systems also with decision making that is whether the culture meets the ecological conditions of the region. One of the methods of irrigation management approach that stands out the most optimum amount of water to be offered to culture is the estimate of crop evapotranspiration (ETc). Therefore, this study aimed to determine the crop evapotranspiration (ETc) and crop coefficient (Kc) for different stages of crop development watermelon. We used the Crimson Sweet variety, sown at a spacing of 1.5 mx 0.75 m where the irrigation system was used drip. Therefore, an experiment was conducted at the experimental unit of Academic Garanhuns/UFRPE, from 01/02/2013 to 07/04/2013. The calculation of Kc was obtained by the ratio of ETc and ETo calculated by the method of soil water balance and estimated by the method of Class A pan, respectively, from 01 to 66 days after planting (DAP). The average evapotranspiration of watermelon crop in 66 days the balance was 11.36 mm day-1 and the average values of crop coefficients (Kc) obtained by the relationship between ETc and ETo were 1.80, 1.97, 1, 84 and 1.60 for the vegetative stage, flowering, ripening and harvesting, respectively, and the maximum water consumption by the crop yield in the flowering stag

scholarly journals Measurements of the actual evapotranspiration and crop coefficients of summer and winter seasons crops in Japan

2009 ◽  
Vol 55 (No. 3) ◽  
pp. 121-127 ◽  
Author(s):  
P. Attarod ◽  
M. Aoki
Keyword(s):  
Winter Season ◽  
Ground Surface ◽  
Crop Coefficient ◽  
Bowen Ratio ◽  
Irrigation Scheduling ◽  
Summer Season ◽  
Actual Evapotranspiration ◽  
Rye Grass ◽  
Balance Technique ◽  
Crop Coefficients

The main goal was to understand the trends of actual evapotranspiration (AET) and crop coefficient (<I>K<sub>c</sub></I>) in summer and winter seasons crops in Japan, maize, soybean, wheat and Italian rye-grass. Bowen ratio energy balance technique (BREB) was applied to measure the AET and heat flux between ground surface and atmosphere. Measurements were carried out using an automatic weather station (AWS) installed seasonally in the experimental farm of Tokyo University of Agriculture and Technology (TUAT). Penman-Monteith equation recommended by FAO was used to calculate reference crop evapotranspiration (ET<SUB>0</SUB>) and <I>K<sub>c</sub></I> was obtained from the ratio of AET to ET<SUB>0</SUB>. The results indicated that the average amount of daytime AET in the winter and summer seasons crops were approximately 2.5 and 3.5 mm, respectively monthly daytime. Daytime AET varied between 1.3 and 5.7 mm in winter season crops and between 1.4 and 6.5 mm in summer season crops. No significant differences between daily average values of AET for winter season as well as for summer season crops were found at 5% level of confidence (<I>t</I> = 0.9278, wheat and Italian rye-grass and <I>t</I> = 0.6781, soybean and maize). Average <I>K<sub>c</sub></I> values of summer season crops were found to be slightly higher than those of winter seasons crops. For planning the irrigation scheduling, it is quite necessary to understand the behaviors of AET and <I>K<sub>c</sub></I> during the growing season.

scholarly journals Estimation of crop water requirements: extending the one-step approach to dual crop coefficients

2015 ◽  
Vol 12 (5) ◽  
pp. 4933-4963 ◽  
Author(s):  
J. P. Lhomme ◽  
N. Boudhina ◽  
M. M. Masmoudi ◽  
A. Chehbouni
Keyword(s):  
Surface Resistance ◽  
Crop Coefficient ◽  
Soil Surface ◽  
Stomatal Resistance ◽  
Crop Water ◽  
Water Requirements ◽  
Crop Water Requirements ◽  
One Step ◽  
Crop Coefficients ◽  
Monteith Equation

Abstract. Crop water requirements are commonly estimated with the FAO-56 methodology based upon a "two-step" approach: first a reference evapotranspiration (ET0) is calculated from weather variables with the Penman–Monteith equation; then ET0 is multiplied by a tabulated crop-specific coefficient (Kc) to determine the water requirement (ETc) of a given crop under standard conditions. This method has been challenged to the benefit of a "one-step" approach, where crop evapotranspiration is directly calculated from a Penman–Monteith equation, its surface resistance replacing the crop coefficient. Whereas the transformation of the two-step approach into a one-step approach has been well documented when a single crop coefficient (Kc) is used, the case of dual crop coefficients (Kcb for the crop and Ke for the soil) has not been treated yet. The present paper examines this specific case. Using a full two-layer model as a reference, it is shown that the FAO-56 dual crop coefficient approach can be translated into a one-step approach based upon a modified combination equation. This equation has the basic form of the Penman–Monteith equation, but its surface resistance is calculated as the parallel sum of a foliage resistance (replacing Kcb) and a soil surface resistance (replacing Ke). We also show that the foliage resistance, which depends on leaf stomatal resistance and leaf area, can be inferred from the basal crop coefficient (Kcb) in a way similar to the Matt–Shuttleworth method.

scholarly journals UAV Multispectral Imagery Combined with the FAO-56 Dual Approach for Maize Evapotranspiration Mapping in the North China Plain

2019 ◽  
Vol 11 (21) ◽  
pp. 2519 ◽  
Author(s):  
Jiandong Tang ◽  
Wenting Han ◽  
Liyuan Zhang
Keyword(s):  
Water Stress ◽  
Vegetation Index ◽  
Estimation Method ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
Stress Index ◽  
Crop Water ◽  
Crop Water Stress Index ◽  
Water Stress Condition ◽  
Crop Water Stress

As the key principle of precision farming, variation of actual crop evapotranspiration (ET) within the field serves as the basis for crop management. Although the estimation of evapotranspiration has achieved great progress through the combination of different remote sensing data and the FAO-56 crop coefficient (Kc) method, lack of the accurate crop water stress coefficient (Ks) at different space–time scales still hinder its operational application to farmer practices. This work aims to explore the potential of multispectral images taken from unmanned aerial vehicles (UAVs) for estimating the temporal and spatial variability of Ks under the water stress condition and mapping the variability of field maize ET combined with the FAO-56 Kc model. To search for an optimal estimation method, the performance of several models was compared including models based on Ks either derived from the crop water stress index (CWSI) or calculated by the canopy temperature ratio (Tc ratio), and combined with the basal crop coefficient (Kcb) based on the normalized difference vegetation index (NDVI). Compared with the Ks derived from the Tc ratio, the CWSI-based Ks responded well to water stress and had strong applicability and convenience. The results of the comparison show that ET derived from the Ks-CWSI had a higher correlation with the modified FAO-56 method, with an R2 = 0.81, root mean square error (RMSE) = 0.95 mm/d, and d = 0.94. In contrast, ET derived from the Ks-Tc ratio had a relatively lower correlation with an R2 = 0.68 and RMSE = 1.25 mm/d. To obtain the evapotranspiration status of the whole maize field and formulate reasonable irrigation schedules, the CWSI obtained by a handheld infrared thermometer was inverted by the renormalized difference vegetation index (RDVI) and the transformed chlorophyll absorption in reflectance index (TCARI). Then, the whole map of Ks can be derived from the VIs by the relationship between CWSI and Ks and can be taken as the basic input for ET estimation at the field scale. The final ET results based on multispectral UAV interpolation measurements can well reflect the crop ET status under different irrigation levels, and greatly help to improve irrigation scheduling through more precise management of deficit irrigation.

scholarly journals Assessment of Soybean Evapotranspiration and Controlled Water Stress Using Traditional and Converted Evapotranspirometers

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 830
Author(s):  
Angela Anda ◽  
Brigitta Simon ◽  
Gabor Soos ◽  
Jaime A. Teixeira da Silva ◽  
Zsuzsanna Farkas ◽  
...  
Keyword(s):  
Water Stress ◽  
Crop Coefficient ◽  
Weather Conditions ◽  
Crop Water ◽  
Growing Seasons ◽  
Water Demands ◽  
Naturally Occurring ◽  
Air Temperatures ◽  
Water Response ◽  
Selection Of

Evapotranspiration (ETR), reference evapotranspiration (ET0), and seasonal ETR totals were determined for soybean over two growing seasons, at Keszthely, Hungary, using traditionally operated and converted evapotranspirometers. The study aimed to document the plant–water response of two soybean varieties (Sinara: Sin; Sigalia: Sig) which have different water demands. Three water supply treatments were tested: unlimited (WW) watering, 50% of crop water requirement (RO), and rainfed (P). Reconstructed evapotranspirometers allowed crop water deprivation to be simulated under field conditions. ETR sums were higher during the cooler 2017 than in the warmer 2018, calling attention to the importance of being informed about more detailed meteorological variables other than monthly (seasonal) means. In addition to variation in daily mean air temperatures (Ta), maximum Ta played a key role in determining ETR under naturally occurring extreme weather conditions in 2018. Irrespective of the variety, daily mean ETR was on average 65–75% greater than in the water-stress treatment. Unexpectedly, water stress-tolerant Sin used slightly more water than Sig, which was bred for standard weather conditions. Measured mean ETR was as much as 10% higher than derived ET0 rates, causing crop coefficient to exceed 1.0 during flowering. Careful selection of the soybean variety when practicing water-saving management may lead to more efficient variety improvement in a breeding program. It may also be important for soybean producers and farmers to adopt the best variety, aiming to decrease the use of irrigation water to increase seed yield.

scholarly journals Comparison of Lysimeter-Derived Crop Coefficients for Legacy and Modern Drought-Tolerant Maize Hybrids in the Texas High Plains

2020 ◽  
Vol 63 (5) ◽  
pp. 1243-1257
Author(s):  
Gary W. Marek ◽  
Thomas H. Marek ◽  
Steven R. Evett ◽  
Jourdan M. Bell ◽  
Paul D. Colaizzi ◽  
...  
Keyword(s):  
Water Use ◽  
Crop Coefficient ◽  
Irrigation Scheduling ◽  
High Plains ◽  
List Type ◽  
Season Length ◽  
Planting Dates ◽  
Corn Hybrids ◽  
Drought Tolerant ◽  
Crop Coefficients

HighlightsDaily maximum crop coefficient (Kc) values were similar for legacy hybrids and a modern drought-tolerant (DT) hybrid.Later planting dates for a DT hybrid resulted in average season lengths ~25 days shorter than those of legacy hybrids.Results illustrated the effects of environment, planting date, interannual variation in temperature, and the importance of climate-specific Kc functions.DT hybrids may be more effective at reproductive growth during periods of heat stress in semi-arid environments, although additional data are needed to support this conclusion.Abstract. Corn (Zea mays L.) is a major irrigated crop grown in the Southern High Plains including the Texas Panhandle. Irrigation from the Ogallala Aquifer is required to sustain profitable corn production in the region by supplementing inadequate and erratic rainfall. Effective irrigation scheduling works to extend limited groundwater resources by avoiding water losses associated with runoff and/or percolation below the root zone. The use of crop coefficient (Kc) and reference evapotranspiration (ETo) values to estimate daily crop water use (ETc) remains an effective scheduling tool that can complement other irrigation scheduling approaches. Both Food and Agriculture Organization (FAO-56) piecewise and curvilinear Kc values for corn are found in the literature. However, advances in corn genetics have led to questions about the applicability of Kc values developed using legacy corn hybrids to irrigation of modern drought-tolerant (DT) hybrids. Lysimeter-derived Kc values for legacy corn hybrids grown in large weighing lysimeter fields at the USDA-ARS Conservation and Production Research Laboratory at Bushland, Texas, were compared with those derived from a modern DT corn hybrid recently grown in the same fields. Results indicated that although midseason daily Kc values were similar for all hybrids, average season length was ~25 days shorter for the modern DT hybrid, characterized by a shortened initial growth period followed by more rapid increase of Kc during the development period. However, plots of Kc over thermal time illustrated that the differences in season length were likely attributable to later planting dates associated with the DT corn hybrids. Average seasonal water use was 730 and 811 mm for the legacy and modern DT hybrids, respectively (three years each), with corresponding average yields of 1.2 and 1.4 kg ha-1. Results suggest that published Kc and Kcb values developed with legacy corn hybrids remain largely applicable to modern DT corn hybrids when used with accurate estimates of effective canopy-based growth stages and climate-specific Kc functions. Keywords: Crop coefficients, Drought-tolerant, Evapotranspiration, Maize, Weighing lysimeters.

scholarly journals Variation of Actual Corn (Zea Mays L.) Evapotranspiration, Single and Dual Crop Coefficient Under Different Point Source Irrigation Systems in a Semiarid Region

2021 ◽  
Author(s):  
Elahe Kanani ◽  
Hossein Dehghanisanij ◽  
Samira Akhavan
Keyword(s):  
Drip Irrigation ◽  
Smallholder Farmers ◽  
Irrigation System ◽  
Crop Coefficient ◽  
Semiarid Region ◽  
Irrigation Systems ◽  
Biological Yield ◽  
Semi Arid Region ◽  
Water Scarce ◽  
Crop Coefficients

Abstract Paying attention to irrigation of corn could have significant attention on water resources. The experiment was carried out to consider the influence of porous capsule irrigation (PCI), surface drip irrigation (DI) and subsurface drip irrigation (SDI) systems under mulch condition on actual evapotranspiration (ETc act), crop coefficients (Kc single and Kc dual), yield and water use efficiency (WUE) of corn in a semi-arid region of Iran. The experiment was arranged in a split-plot design with three irrigation systems as the main-factor and two soil coverage with mulch (M1) and non- mulch (M2) as sub- factor. The results showed that corn ETc act varied significantly with different irrigation systems (P < 0.05), and was reported 389.8, 377.0 and 372.8 mm for PCI, DI and SDI systems, respectively. The highest value of Kc average and Kcb (0.82 and 1.22, respectively) and the minimum value of Ke (0.12) were seen in PCI system. The dry and wet biological yield were the highest in (PCI + M1) treatment (29.98 and 107 ton/ ha, respectively), and the lowest dry and wet biological yield were recorded in (DI + M2) treatment (23.19 and 58.54 ton/ha, respectively). The highest WUE (7.89 kg/m3) were recorded in (PCI + M1) treatment. Using PCI system leads to higher biological yield, WUE and IWUE in comparison to DI and SDI systems. Accordingly, PCI system as an alternative to drip irrigation system can be a viable option for water scarce area particularly for smallholder farmers.

scholarly journals Evaluating the Irrigation Practice of Center Pivot Sprinkler Irrigation System at Hiwot Agricultural Mechanization, Ethiopia

2019 ◽  
pp. 1-7
Author(s):  
Kasa Mekonen Tiku ◽  
Pratap Singh
Keyword(s):  
Flow Rate ◽  
Irrigation System ◽  
Sprinkler Irrigation ◽  
Irrigation Scheduling ◽  
Water Requirement ◽  
Crop Water Requirement ◽  
Crop Water ◽  
Irrigation Practice ◽  
Center Pivot ◽  
Actual Flow Rate

Irrigation practice evaluation of center pivot sprinkler irrigation system at Hiwot Agricultural Mechanization farm, North/west Ethiopia was conducted. The aim of the study was evaluating the existing center pivot irrigation practice in terms of irrigation scheduling. Measuring flow rate of center pivot machines for existing irrigation practice and Crop water requirement based scheduling was used to evaluate the system. The highest value of crop water requirement at location m6, m7 and m12 was 5.24 mm/day in September at mid-stage and for location m4 and m8 in October at mid-stage equal to 4.99 mm/day. Whereas, the lowest crop water requirement at location m6, m7 and m12 was 2.52 mm/day in July at the initial stage which was and for location m4 and m8 in august at initial stage equal to 2.08 mm/day. The actual flow rate of center pivot machines varies from 0.7l/s for m7 to a maximum of 1l/s for m4 whereas estimated crop water requirement flow rate varies from 0.6l/s for m6 to a maximum of 0.8l/s for m4. The study also revealed that the actual flow rate of the nozzles was excess. Therefore improvement of center pivot sprinkler irrigation system can be amended by using proper irrigation scheduling and by introducing an automatic control system.

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