Evapotranspiration and components of corn (Zea mays L.) under micro irrigation systems in a semi-arid environment

Aim of study: This work summarizes the influence of surface drip irrigation (DI) and subsurface drip irrigation (SDI) systems on corn growth indices and actual evapotranspiration (ETc-act) and its components of plant transpiration (Tp) and soil evaporation (E).Area of study: Karaj, IranMaterial and methods: The experimental soil was loamy. The corn ETc-act of each mini-lysimeter was measured based on the water balance method. The E was measured using two mini-lysimeters and Tp was estimated from the difference between ETc-act and E.Main results: The resulting data showed that the ETc-act was lower under SDI (384.8 mm) than under DI (423.4 mm). The Kcb-m for the corn increased after sowing and peaked during the mid-season stage, with an average value of 0.47, a minimum value of 0.0 and maximum value of 1.52 under DI and 0.53, 0.0 and 1.74 respectively, under SDI. For Ke-m, the average, minimum and maximum values were 0.33, 0.20 and 0.58 under DI and 0.23, 0.15 and 0.46 respectively, under SDI. The biomass yield was much higher under SDI (81.90 ton/ha) than under DI (63.21 ton/ha). Less E and more Tp occurred under SDI than under DI. SDI achived superior WUE (8.32 kg/m3) compared with DI.Research highlights: SDI was superior to DI based on biomass yield, corn height, stem diameter, and leaf area index which contributed to more favorable soil moisture conditions and low weed incidence; Thus, the SDI system is more productive and would better increase WUE than the DI system

Conditioning DRASTIC model to simulate nitrate pollution case study: Hamadan-Bahar plain

One of the major causes of groundwater pollution in Hamadan-Bahar aquifer in western Iran is a non-point source pollution resulting from agricultural activities. Withdrawal of over 88% of drinking water from groundwater resources, adds urgency to the studies leading to a better management of water supplies in this region. In this study, the DRASTIC model was used to construct groundwater vulnerability maps based on the "intrinsic” (natural conditions) and "specific” (including management) concepts. As DRASTIC has drawbacks to simulate specific contaminants, we conditioned the rates on measured nitrate data and optimized the weights of the specific model to obtain a nitrate vulnerability map for the region. The performance of the conditioned DRASTIC model improved significantly (R 2=0.52) over the intrinsic (R 2=0.12) and specific (R 2=0.19) models in predicting the groundwater nitrate concentration. Our study suggests that a locally conditioned DRASTIC model is an effective tool for predicting the region's vulnerability to nitrate pollution. In addition, comparison of groundwater tables between two periods 30years apart indicated a drawdown of around 50m in the central plain of the Hamadan-Bahar region. Our interpretation of the vulnerability maps for the two periods showed a polluted zone developing in the central valley requiring careful evaluation and monitorin

Determining the Most Compatible Method for Estimating Infiltration Parameters in Mathematical Furrow Irrigation Models

Introduction: Surface irrigation is still the most used method. For accessing to high efficiency, irrigation requires careful design and correct implementation. In addition, the design and evaluation of these systems require the identification of the advance, recession, and infiltration curves. Infiltration is the most important and difficult parameter to evaluate surface irrigation systems. The objective of this study was to evaluate five different methods to estimate infiltration parameters (two-point method of Elliott and Walker, recycling furrow infiltrometer, Singh and Yu method, Shepard one-point method and modified Shepard et al. two-point method) and to determine the most compatible method with design and evaluation models of furrow irrigation (hydrodynamic, kinematic wave and zero inertia) by applying SIRMOD software. Materials and Methods: For the simulation of the surface irrigation, the continuity and momentum equations (Sant-Venant equations) used. SIRMOD simulation model is one of the models for the management and design of surface irrigation systems. The software package, hydraulic hydrodynamic models, zero inertia and kinetic wave have been placed. These models are resolvent of the Sant-Venant equations based on various assumptions. In this study, two-point method of Elliott and Walker, recycling furrow infiltrometer, Singh and Yu method (to calculate the coefficients of Kostiakov-Louis equation), Shepard one-point method and modified Shepard et al. two-point method (to calculate the coefficients of Philip equation), were used for estimating infiltration parameters. For this purpose, three field data sets were used. The total infiltrated water volume and advance time were predicted in each infiltration method and irrigation simulation model. In order to compare and evaluate the mentioned methods, the relative and standard errors were calculated. Results and Discussion: According to the five methods (two-point method of Elliott and Walker, recycling furrow infiltrometer, Singh and Yu method, Shepard one-point method and modified Shepard et al. two-point method) Kostyakof- Louis and Philippe equations coefficients were determined. To evaluate the different methods for estimating infiltration parameters, the volume of water penetration in the furrow length was estimated using five named methods and the findings were compared with the actual volume of infiltrated water in the furrows (was estimated using the input-output hydrograph). Values of relative error in estimating the infiltrated volume in the furrows show the two-point Elliott and Walker method with 9.2 percent relative error is the lowest error than other methods. Then recycling furrow infiltrometer (back water) method is with 21.4 percent relative error. The standard error in the simulation and predict the advance stage in furrows based on different estimated parameters showed that hydrodynamic model by two-point Elliott and Walker method will give the best results (with 12.86 percent standard error). Also in Kinetic Wave model, recycling furrow infiltrometer method has the lowest standard error (10.04 percent) and zero inertia models with two-point Elliott and Walker method have lowest standard error (12.81 percent). In Hydrodynamic and zero inertia models, recycling furrow infiltrometer and two-point method of Elliott and Walker and Singh and Yu method have estimated advance figures in furrow less than its actual value. Shepard et al. one-point method underestimated about 100 meters of furrow length and overestimated from this point to the end of the furrow. Modified Shepard et al. two-point method is generally overestimated. In the kinetic wave model, two-point Elliott and Walker and recycling furrow infiltrometer methods numbers have been estimated to be completed in accordance with the numbers seen in a distance of about 40 meters along the furrow and the low estimate since the end of the furrow. Singh and Yu method overestimated. Shepard et al. one-point and Modified Shepard et al. two-point method were like the other two models. Conclusions: Elliott and Walker two-point method is generally the least error in the calculation of the total volume of infiltrated water through the grooves, compared to other methods and then using rotating penetrometer (back water) is located. In general it can be said that both recycling furrow infiltrometer and two- point Elliott and Walker, the most appropriate methods to determine the infiltration equation parameters than other methods under study and using them in all three hydrodynamic, kinematic wave and zero inertia models, the results of the simulation irrigation, have created the smallest error. In general, the kinetic wave model than hydrodynamic and zero inertia models, was estimated more accurately the data in water advance stage and this trend can be seen in every five methods for estimating the infiltrated parameters. However, calculated errors in both hydrodynamic and zero inertia models in predicting this stage of irrigation are almost equal

Evapotranspiration and components of corn (Zea mays L.) under micro irrigation systems in a semi-arid environment

Aim of study: This work summarizes the influence of surface drip irrigation (DI) and subsurface drip irrigation (SDI) systems on corn growth indices and actual evapotranspiration (ETc-act) and its components of plant transpiration (Tp) and soil evaporation (E).Area of study: Karaj, IranMaterial and methods: The experimental soil was loamy. The corn ETc-act of each mini-lysimeter was measured based on the water balance method. The E was measured using two mini-lysimeters and Tp was estimated from the difference between ETc-act and E.Main results: The resulting data showed that the ETc-act was lower under SDI (384.8 mm) than under DI (423.4 mm). The Kcb-m for the corn increased after sowing and peaked during the mid-season stage, with an average value of 0.47, a minimum value of 0.0 and maximum value of 1.52 under DI and 0.53, 0.0 and 1.74 respectively, under SDI. For Ke-m, the average, minimum and maximum values were 0.33, 0.20 and 0.58 under DI and 0.23, 0.15 and 0.46 respectively, under SDI. The biomass yield was much higher under SDI (81.90 ton/ha) than under DI (63.21 ton/ha). Less E and more Tp occurred under SDI than under DI. SDI achived superior WUE (8.32 kg/m3) compared with DI.Research highlights: SDI was superior to DI based on biomass yield, corn height, stem diameter, and leaf area index which contributed to more favorable soil moisture conditions and low weed incidence; Thus, the SDI system is more productive and would better increase WUE than the DI system

Assessment of consumer-grade camera-derived vegetation indices for monitoring nitrogen and leaf relative water content of maize

Aim of study: To develop non-destructive and rapid monitoring of water and nitrogen status in maize crops. Area of study: Bu-ali Sina University, Hamedan province, Iran. Material and methods: We used a low-cost modified consumer-grade camera to extract 40 vegetation indices for monitoring leaf N concentrations, SPAD values and relative water content (RWC). In this regard, 528 images taken by the low-cost camera in two consecutive years (2017 and 2018) from maize plants cultivated in a greenhouse under different irrigation and N treatments were evaluated. Main results: Results showed that the best performance outcomes regarding the studied vegetation indices were MCARI, CTVI and CR for SPAD values; MCARI, HUE and CTVI for leaf N concentrations; and TRVI, NDVI and DVI for RWC. In order to increase accuracy of estimated measured data, multiple linear regression equations with combinations of the MCARI, TRVI, NDVI and EVI indices were used. As observed, R2 value was 0.91, 0.60 and 0.90 for SPAD, leaf N concentration and RWC estimation, respectively. Research highlights: The combination of MCARI, TRVI, NDVI and EVI indices provided more accuracy to most of the previous single variable regression models

Explaining the Performance Evaluation Dimensions of Physicians in Tehran University of Medical Sciences (Phenomenological Study)

Background and Aim: Effective monitoring and evaluation of human resources in countries require an agreed set of indicators and measurement tools. Due to the existence of different payment mechanisms, this study aimed to identify performance evaluation indicators in hospitals affiliated with the Tehran University of Medical Sciences. Materials and Methods: A qualitative phenomenological study was conducted in 2022. Data were collected using semi-structured interviews, purposive sampling, and participation of 23 members of the Senior executives and financial team of hospitals affiliated to Tehran University of Medical Sciences and analyzed by content analysis method using MAXQDA-10 software. Results: Twenty-three experts participated in this research, 78.2% were men and 21.7% were women, and a total of 526 final codes were identified and according to the balanced scorecard management tool in 4 main themes of finance, customers, internal processes, and growth and Development. Also 8 sub-themes of resource efficiency with 86%, medical tourism with 52%, professional ethics with 65%, satisfaction with 78%, accreditation with 48%, diagnosis and treatment with 78%, education with 56% and The research was categorized with 78%. Conclusion: The provision of optimal medical services requires managers to be aware of the performance of subordinate personnel, which makes it possible to choose the appropriate criteria, develop performance evaluation systems and conduct correct evaluation, informing Doctors regarding the indicators considered for more accurate evaluation are among the suggestions that can be a solution to the existing problems. Another important point considering the limited available resources is the role of doctors in the field of health tourism to which attention will lead to an increase in financial resources