Climatic water balance in Hamelmalo, Eritrea

Agricultural production is an important sector for peoples to live, but it is highly affected by climate change. To have a good production we need to understand the climatic parameters which adversely affect production. Hamelmalo, which is located in the semi-arid area of Eritrea, is vulnerable to climate change and this is realised in the total production loss. Nevertheless, there is no concrete reference about the climate of the region due to lack of data for a long time. Changes in precipitation (P), evapotranspiration (ET) and, implicitly, in the climatic water balance (CWB), are imminent effects of climate change. However, changes in the CWB, as a response to changes in P and ET, have not yet been analysed thoroughly enough in many parts of the world, including Eritrea. This study also explores the changes of the CWB in the Hamelmalo region, based on a wide range of climatic data (P, relative air humidity and evaporation pan necessary for computing potential evapotranspiration (PET) with the pan evaporation method) recorded at Hamelmalo from 2015-2019. This analysis shows that the annual cumulative CWB for Hamelmalo is negative in 67% of the years. The dry season without precipitation leads to negative CWB and the change in CWB only starts from the raining or crop season. Based on this recent study, 2015 had the highest PET and lowest P, and this resulted in the lowest CWB in the investigated period. Opposite to this, 2019 had lower PET and highest P, which led to the highest CWB. However, the monthly values of CWB did not correlate with the annual P or ET. On the base of our study, it can be concluded that PET and P were very variable in the investigated years and P was the most influential elements of CWB.

Determination of the chemical compounds and mineral contents in tomatoes (Solanum lycopersicum L.) grown under deficit irrigation conditions

The purpose of this study was to investigate the effect of deficit irrigation applications on the chemical compounds and mineral contents of tomatoes. In the study, a tomato (Solanum lycopersicum L) hybrid "Nehir F1" was grown in a greenhouse that had a natural light, heating and ventilation system and was covered with polycarbonate material. The tomatoes were irrigated every three days by applying 60% (T1), 80% (T2), 100% (T3) and 120% (T4) of the evaporation value after reading and determining it from the reduced evaporation pan. The tomatoes were harvested at the red-ripe maturity stage and analyses were performed. As a result of the study a total of 60 compounds were determined in the tomato samples by using Gas chromatography/Mass Spectrometer system. The most abundant compounds in terms of both amount and variety in the tomatoes were identified as ketones, sugars and fatty acid esters. Furthermore, the mineral content of the tomatoes changed according to the irrigation application. K, Mg, P, Ca and Fe were accumulated in the all tomatoes samples.

Scenarios to reduce evaporation from class A evaporation pan by using windbreaks

Evaporation from reservoirs and lakes is an important processes frequently occurring in dry, hot regions such as Iraq. In order to preserve the environment and to reduce the amount of evaporation from open water bodies in this study, simulation was performed to reduce evaporation from evaporation basin class A by using windbreaks natural (Conocarpus trees). Three basic scenarios were made that depended on the values of the atmospheric elements affecting the evaporation process in summer according to the modified Penman equation for the conditions of Iraq, the climate factors are temperature, solar radiation, wind speed, dew point, and the effect of the number of windbreaks and their height was also introduced in sub- scenario. Experiments have shown that the best sub-scenario for all basic scenarios is when the windbreaks are placed in a direct direction to the wind blowing on the evaporation basin in the form of three rows, each row contains three trees where the windbreaks are in case cross and the height of the trees is 100 cm and the distance between each tree and another, and between each row and row 15 × 15 cm, the results of this subscenario recorded the highest rate of evaporation reduction up to 35% of its original value before using windbreaks.

SOIL MULCHING AND DEFICIT IRRIGATION WITH WASTEWATER IN THE QUALITY OF ITALIAN ZUCCHINI

Conscious agricultural management, which aims to conserve natural resources, has been the target of contemporary agriculture. In this context, the reuse of water in deficit water depth in agricultural irrigation becomes a viable technique, and this work aimed to evaluate the effect of different irrigation depths with wastewater and soil mulching on the microbiological and postharvest characteristics of the Italian zucchini. The experiment was conducted in the field conditions with a randomized block design in a split-plot arrangement. Four irrigation depths (100%, 85%, 70%, and 55% of the estimated ETc from the Class A Evaporation Pan) and three types of soil mulching (rice husk, double-sided black and white polyethylene film, and uncovered soil) were analyzed. Texture, titratable acidity (TA), soluble solids content (ºBrix), pH, and the ºBrix:TA ratio of the Italian zucchini were analyzed, besides the microbiological analysis. The irrigation depth or soil mulching did not influence the pH of the Italian zucchini. The uncovered soil promoted higher titratable acidity to the Italian zucchini. The texture of the fruit, the soluble solids, and the ºBrix:TA ratio was influenced by the types of soil mulching and irrigation depths. The use of wastewater for drip irrigation reduces the effects of the microbial load on the crop.

Kalibrasi Persamaan Thornthwaite Dan Evaporasi Panci Untuk Memprediksi Evapotranspirasi Potensial Pada Daerah Dengan Data Cuaca Terbatas

Determination of irrigation channel dimensions is determined by the number of consumptive use values that are empirically determined by the potential evapotranspiration value (ETo). Due to the limited lysimeter measurement data, the ETo value is usually approached by an empirical method using weather data input. The recognized standard method for its reliability and can be used universally in determining ETo values is the FAO Penman-Monteith method. However, the use of this method is only possible if complete weather data is available. This study modified the simplest ETo calculation method, the Thornthwaite method and the evaporation pan method to obtain ETo values as accurate as FAO PM resulted. Callibrations are made by finding the correction number to get the best results shown by the high of correlation number and the efficiency index value. The results obtained are for the area with limited weather data condition, the Thornthwaite method both before and after calibration has better accuracy than the evaporation pan method. While the calibration carried out successfully increased the correlation number and efficiency index of both methods significantly. The results of the two calibrated methods, the Thornthwaite method provides better and satisfactory performance with a ratio between 0.86 and 0.89 and the efficiency index reaches 0.78.

Integrated application of biochar and bio-fertilizer improves yield and yield components of Cowpea under water-deficient stress

A low amount of organic matter and insufficient irrigation are two main challenges facing successful crop production in arid and semiarid regions. Application of biochar as an organic amendment to soil not only can help increase organic matter in soil, but also may alleviate adverse effects of water deficit on plant growth and yield production. To test this hypothesis, a two-year field experiment was conducted to assess the effect of sugarcane biochar on yield and yield components of cowpea in water-deficient soil. Treatments consisted of two levels of seed treatment with nitroxin, three levels of biochar application (0, 4, and 8 ton/ha), and a threelevel irrigation regime (60, 90, and 120 mm from evaporation pan class A), laid out in a split-factorial design. Results showed that the seed number per plant was significantly higher in cowpea when grown with biochar, possibly due to the relief of water-deficient stress and higher phosphorus and potassium content. Biomass production of cowpea declined under a severe waterdeficit condition (ir3) compared to normal irrigation (ir1) in 2018 and 2019, decreasing by 39% and 42%, respectively. The maximum biomass obtained from application of 8 ton/ha biochar reached 617.43 and 664.92 g/m2 in 2018 and 2019, respectively. Seeds treated with nitroxin exhibited 10% and 8% greater biomass production in 2018 and 2019 as compared with control treatments. Seed yield increased with the addition of biochar to soil under all irrigation regimes; however, the maximum seed yield of 266.46 and 275.36 g/m2 was observed when there was no water-deficient stress condition and application of 8 ton/ha biochar in 2018 and 2019, respectively.

Estudio del proceso de evaporación en el Salar Tres Quebradas por medio de medidas in situ y datos de satélite

<p>The calculation of evaporation (<em>Ev</em>) is a fundamental process on the planning of investment for nonmetallic mining in salt flats. Dispose to reliable estimates of evaporation allows to reduce one of the main uncertainties of the flow models in this type of basin. This paper focuses on the calculation of <em>Ev</em> in the Tres Quebradas salt flat, Catamarca (Argentina), applying Priestley-Taylor model whit satellite data. Study area comprises the Tres Quebradas and Verde lagoons, and a central evaporite zone. Satellite data (CERES and OLI-LandSat 8), meteorological information, brine density measurements, evaporation measurements, and spectral signatures to calculations were used. The lagoons evaporation was estimated and by means of a Class A evaporation pan validated. The evaporation control in evaporite zones also was studied using a phreatic level function. <em>Ev</em> values of 1302 mm year^–1 and 1249 mm year^–1 for the Tres Quebradas and Verde lagoons were obtained, respectively, similar to Class A evaporation pan values measured. In the case of evaporite zones, an average annual value of 152 mm year^–1 was estimated, regulated by the phreatic level. In summary, an average annual of system water loss by evaporation of 1.31±0.32 m³ s^–1 was obtained, where more than 80% corresponds to the Tres Quebradas and Verde lagoons, and the rest to the central evaporite zone. The results achieved are consistent and will be used as input data in the numerical flow modeling to the estimation of the lithium brine reserve of the salt flats.</p>

Optimal amounts of water and nitrogen applied to sugar beet when crop price depends on its sugar content

Aim of study: To derive mathematical formulas to determine the optimum amounts of applied water and N at variable crop prices and rainfall conditions for sugar beet.Area of study: Karaj Research Center, Alborz Province, IranMaterial and methods: At first, mathematical formulas were derived to determine optimum applied water and nitrogen for sugar beet under rainfall occurrence, land limited (in cases that arable land area is limited and the farmer can not put more land area under irrigation) and water limited conditions when crop price depends on sugar content. Second, this theory was applied to analyze the relevant experimental data. The experiment was a split-plot design with irrigation treatments as the main plots (40%, 80%, 120% and 160% of evaporation from the surface of class A evaporation pan) and N fertilizer rates (0, 90, 180 and 270 kg N/ha) as subplots.Main results: Under land and water limiting conditions, deficit irrigation of 27% and 48% led to 6.4% and 25.4% decrease in yield and 21.4% and 96.2% increase in total net income, respectively, compared with full irrigation. Under water limiting conditions, cultivated land area increased by 93.7, 108 and 128% for 0, 60 and 120 mm rainfall, respectively. Under land limiting conditions, amounts of optimum irrigation water were 12381.2, 11781.2 and 11181.2 m3/ha, for 0, 60 and 120 mm rainfalls, respectively. The corresponding values for N were 262.5 kg/ha in all three rainfall quantities. Besides, under water limiting conditions, optimum amounts of irrigation water were 8708.1, 7828.8 and 6882.1 m3/ha for 0, 60 and 120 mm rainfalls, respectively. The corresponding values for N were 301.1, 299.5 and 295.5 kg/ha, respectively. Optimum amounts of irrigation water and N decreased by increase in rainfall amount.Research highlights: Under limited irrigation water conditions, if the rainfall, residual N, water cost and base crop price increases, the value of optimum applied water should be decreased.

Direct Measurements and New Mathematical Methods to Estimate the Pond Evaporation of the French Midwest

<p><em>Despite many scientific papers published around the world on the evaporation of water bodies, few detailed evaporation studies exist for ponds, especially the ponds of humid areas like the French Midwest. Two full years of daily evaporation measurements on two different types of ponds were carried out using a transparent floating evaporation pan. A comparison between a class A evaporation pan and the transparent floating evaporation pan shows that the latter has almost no influence on the water temperature. As a consequence, the measurements taken by this evaporation pan were used to evaluate the reliability of 18 different mathematical methods. These mathematical methods use climate data provided by a weather station installed at the edge of the studied ponds to calculate evaporation. The comparison between measured and calculated evaporation shows that the new empirical formula of Aldomany is the best formula that we can use to estimate the ponds evaporation.</em><strong><em></em></strong></p>