EVALUATION OF THE ACCURACY OF EVPOTRANSPIRATION IN THE EVAPO MOBILE APPLICATION

The article presents the results of the study on the accuracy of evapotranspiration in the EVAPO mobile application. The aim of the work is to provide recommendations on the effective use of the mobile application for the prompt, low-cost and convenient determination of evapotranspiration and planning the irrigation regime. Materials and methods. The study was conducted in the autumn of 2020 and in the summer of 2021 using meteorological data from Kherson Regional Hydrometeorological Station, which were used for reference calculations of evapotranspiration according to the method recommended by FAO (Penman-Monteith equation) in the ETo Calculator software. The calculated values of the reference evapotranspiration and those obtained in the EVAPO mobile application were compared with each other through the computation of the correlation coefficients, determination coefficients and mean absolute percentage errors to assess the accuracy of the data on the studied agrometeorological index in the mobile application. Statistical calculations and graphical models were performed using Microsoft Excel 365 spreadsheet processor. Polynomial regression was applied to calibrate and enhance the performance of original EVAPO application. Results. It was found that the EVAPO mobile application without additional calibration cannot provide the proper accuracy of the evapotranspiration calculation. During the cold period of the year (October-November) the mean absolute percentage error was 137.02 %, and during the warm period (May-August) it was 41.43 %. The general error of the calculation in the mobile application compared to the ETo Calculator reference values was 88.75 %. At the same time, EVAPO makes it possible to accurately track the trend of evapotranspiration dynamics, the coefficient of determination of the model is 0.86. In the warm period of the year, there is a tendency to overestimate the value of evapotranspiration, and in the cold period of the year, no clear pattern was found. The evapotranspiration values adjusted by the polynomial regression model obtained in the EVAPO mobile application allow their use in operational irrigation planning. Conclusions. The EVAPO mobile application is a convenient, accessible tool for the rapid assessment of evapotranspiration. However, its implementation on the territory of Ukraine cannot be recommended without preliminary calibration for each specific agroclimatic zone due to enormous errors in the estimation of evapotranspiration value.

Water requirement and water use efficiency of Sorghum and its irrigation planning under limited water resources in arid and semi arid regions of India

Water requirement and water use efficiency of sorghum was studied at Akola, Parbhani, Rahuri and Coimbatore. The study enables to understand the consumptive water demand of sorghum and water use efficiency in relation to yield. The results can be used for efficient management of both rainfall and limited water resources available for sorghum production. Seasonal Evapotranspiration (ET) losses were studied for non- irrigated kharif sorghum at Akola and Parbhani and for Rahuri and Coimbatore seasonal ET losses were studied for rabi sorghum for well distributed normal and deficit rainfall years. In the normal rainfall years ET losses were more compared to deficit rainfall years. However, water use efficiency was found higher during deficit rainfall years than normal rainfall years. The seasonal ET- yield relationship was found positively correlated but insignificant for Akola, Parbhani, Rahuri and significant for Coimbatore (5% level). At Akola and Parbhani optimum yields were observed for seasonal ET of around 486 mm and 470 mm respectively. At Coimbatore maximum yield was observed for seasonal ET of 416 mm whereas at Rahuri yield was maximum when ET loss was about 475 mm. Water Use Efficiency (WUE) ranged from 6.3 to 12.2 mm for kharif season and 5.5 to 10.1 mm for rabi sorghum. Crop coefficient Kc was found negligible during early growth stages and reached peak during flowering stage and declined subsequently during maturity to harvesting stage. The study revealed that during deficit rainfall years life saving irrigation need to be applied for all stations under consideration. If limited irrigation is available irrigations at vegetative stage (25-35 days after sowing) and at boot- flowering stage (55-65 days after sowing) be given. The boot stage is found to be the most critical stage and if only one irrigation is available, it may be given at this stage. Water stress at this stage is found to cause reduction in yield by 35 to 40%.

Optimization of multi-objective cropping pattern using linear and goal programming approaches

Irrigation planning and scheduling are essential components of water management in irrigated agriculture. For this purpose, optimal allocation of land and water is required for optimization of cropping pattern under a set of limitations. In this paper, an attempt was made to optimize the cropping pattern for Barna irrigation project using Linear and Goal Programming (LP and GP) approaches. Three different objectives such as maximization of net return, protein and calorie values were considered for optimization of cropping pattern. The factors like amount of net return, values of protein and calorie, and quantum of water utilized for irrigation by LP and GP were considered for selection of best approach for optimization of cropping pattern for the project. The paper presents the methodology adopted in optimizing the cropping pattern using LP and GP approaches and the results obtained from the study. GP approach was found to be best for optimization of cropping pattern for the project.

Forecasting East Belitung Regency Rainfall Data by Reviewing Heteroscedasticity

East Belitung Regency is one of the regencies located on Belitung Island. East Belitung Regency has a tropical and wet climate with a fairly high variation of rainfall. Rainfall forecasting is an important thing to model because of the many uses of rainfall forecasting results such as irrigation planning, flood prediction, erosion prediction and others. This study aims to predict rainfall for the next 5 years by using a time series model by reviewing the heteroscedasticity of the data. From the results of the analysis of rainfall in East Belitung Regency with a seasonal pattern. The best model used is ARIMA (0, l, l)(2, l, l)12 with insignificant heteroscedasticity.

Evapotranspiration and Crop Coefficient of Ratoon Rice Crop Determined by Water Depth Observation and Bayesian Inference

Actual crop evapotranspiration (ET) and crop coefficient (Kc) of ratoon rice crop, which are necessary for irrigation planning, have been hardly reported. ET can be directly measured by lysimeter and eddy covariance but it is expensive, so it remains difficult to determine ET, especially in developing countries. The focus of this study was to evaluate the ET and Kc of ratoon cropping in a tropical region of Myanmar using a simplified method. Our method combined the manual observation of water depth in concrete paddy tanks and the ET model estimation using Bayesian parameter inference. The ET and Kc could be determined using this method with an incomplete observation dataset. The total ET of ratoon was 60–70% less than that of the main crop, but this difference was mainly attributed to climate conditions in each cultivation. The Kc regression curve between transplanted rice and ratoon crops was different because of the tillering traits. The results suggest that irrigation scheduling of ratoon cropping in the initial growth stage should take high crop water requirements into account. In addition, the productivity of ratoon crop is equivalent to transplanted rice, which was determined for cultivation in experiment conditions of small concrete tanks. Therefore, further study on ratoon in Myanmar is necessary for clarifying the viability of ratoon cropping.

Characterization of climatic parameters in the perspective of irrigated agriculture in Uttar Kannada district of Karnataka, India

A rainfall and potential evapotranspiration characteristics together determine the agro-meteorological regime of a region and influences decision concerning the magnitudes and timing of irrigation application. In the present study, historical rainfall and climate data pertaining to the study area, Uttar Kannada district, Karnataka, was analyzed with a view to characterizing irrigation water requirements. In addition to rainfall input, an important aspect of the water balance model is the crop evapotranspiration (ETcrop), which is the main factor in determining the irrigation schedule. ETcrop could be estimated by reference evapotranspiration (ET0) and crop coefficient. Atmospheric demand for water is represented by ‘potential evapotranspiration’ (PET) and calculated from climatic variables which is crucial for irrigation planning. It has been reported that the Penman-Monteith method gives more consistently correct ET0 estimates to other ET0 methods. While recognizing the importance of both rainfall and PET, an effective measure is known as the ‘Moisture Availability Index’ (MAI), which is computed as the ratio of 75% dependable rainfall and potential evapotranspiration. An MAI value of 1.00 indicates that dependable precipitation is equal to potential evapotranspiration. An MAI value of 0.33 or less for one month during the crop growing season is considered to be a signal of water deficit resulting reduction in crop yield. The findings of this study on MAI are used to decide the selection of the sowing period of crops so as to avoid water stress during the critical harvesting period.

Karakteristik Infiltrasi dan Potensi Irigasi di Lahan Kering Kecamatan Bayan Kabupaten Lombok Utara

Agricultural development with horticultural crops on dry land is one of the government's efforts to increase dry land productivity so that new paddy fields are created in the Bayan area. Noting that land infiltration capability and its classification are important factors needed in irrigation planning to support the development of horticultural agriculture, so it is necessary to conduct field research on this matter. This study aims to determine the characteristics and classification of land infiltration and determine the trend of irrigation that can be applied. Field infiltration tests were carried out in Anyar and Sukadana villages with 4 test points each. The infiltration rate test in the field was carried out using a double ring infiltrometer and a soil test at the Geotechnical Laboratory, Faculty of Engineering, Unram. Analysis of the data used Horton's formula as a comparison and the results of the analysis were presented in the form of tables and graphs, conclusions were made descriptively. The results showed that the average infiltration rate in Anyar Village was at point 1 = 26.90 cm/hour, point 2 = 14.94 cm/hour, point 3 = 27.33 cm/hour, and point 4 = 8.21 cm/hour with soil including sandy clay. Infiltration rate classification of points 1 and 3 is very fast, point 2 is fast and location 4 is rather fast. For Sukadana Village the infiltration rate was obtained at point 1 = 43.52 cm/hour, point 2 = 36.67 cm/hour, point 3 = 12.86 cm/hour, and point 4 = 10.97 cm/hour, with the condition sandy clay soil. Sukadana's infiltration rate classification points 1 and 2 are very fast and points 3 and 4 are rather fast. Based on the results of the infiltration test, for very fast and fast infiltration, it is potential to apply jet irrigation such as sprinklers or perforations and for rather fast infiltration, drip irrigation can be applied with limited drip system