Deficit Irrigation Using Saline Water of Fruit Trees under Water Scarcity Conditions of Southern Tunisia

Both water scarcity and salinity are major obstacles for crop production in arid parts of Tunisia and require adoption of strategies aimed at improving water-use efficiency. Field experiments on deficit irrigation (DI) of table olive, orange trees, and grapevines with saline water (2 dS m  1) were conducted in the arid region of M denine, Tunisia. Three irrigation treatments were compared with the farmer’s method (FM) over two years (2013–2014): deficit irrigation (DI75) and (DI50), which received 75% and 50% less water than full irrigation (FI), respectively, and full compensation of the crop evapotranspiration (FI). Measurements included seasonal changes in soil water content, soil salinity, yield, fruit quality, and economic return. Results showed that in-season water limitations, roughly between 700–250 mm, caused significant reductions in yield and fruit weight, but improved the total soluble solids of fruits. Under FI, DI75, DI50, and FM, average yields were 26.6, 20.1, 14.7, and 21.2 t ha  1 for orange, 4.5, 4.0, 3.1, and 3.5 t ha  1 for table olive, and 3.8, 3.4, 3.1, and 3.5 t ha  1 for grapevine, respectively. Soil salinity build up increased linearly with decreasing irrigation water. Irrigation water productivity (IWP), although lowest for FM, was relatively high (3.30–4.30 kg m  3 for orange, 0.65–1.20 kg m  3 for table olive, and 0.74–1.30 kg m  3 for grapevine). Economic evaluation showed that the FI strategy generated the greatest net income (1800–6630 USD ha  1), followed by DI75 (1350–3940 USD ha  1), FM (844–4340 USD ha  1), and DI50 (600–2400 USD ha  1). The results show an important potential for reasonably sustaining farmer’s income under increased water scarcity

Root distribution in young olive trees (Olea europaea cv. Chétoui) and agronomic application

The study was carried out to have a comprehensive view of the root system behavior of young olive trees cultivated under field conditions. The experiment involved irrigated trees (Olea europaea L., cv., Chétoui) cultivated at 6x6 m2 spacing in Mornag (36.5°N, 10.2°E), northern Tunisia. The way in which roots explore the soil volume during the first years after planting was explored through ‘in situ’ root system drawings and estimation of root densities. The relationship between canopy and root growth parameters was also investigated. The last section of this paper proposes a methodological approach for determining irrigation requirements of young olive trees and how water supply could be linked to the development of canopy and root system during the first years of cultivation when ground cover and the root system are not completely developed. Some agronomic applications were then deduced concerning water and fertilizers for such orchards. Results show that the main development of the olive root system occurs during the two to four first years of cultivation confining most roots (70%) to the top soil layers (20-40 cm). Maximum root densities were observed at this depth at a distance of 0.4 m from trunks. For young trees, water and fertilizers should be supplied at these depths and distances from trunk to allow easy and efficient root absorption. Obtained results also show a significant relationship between canopy and root areas which can be approximated by a linear model (r = 0.94). The root-canopy ratio estimated from their areas decreased rapidly beginning from the second year after planting, resulting from the establishment of competition between vegetative growth and fruiting. The optimum ratio root length/leaf canopy area of 2.3 km m-2 was found for the six-year-old tree indicating good equilibrium between the above and underground parts. The mathematical model developed on the basis of canopy cover and root extension allows precise esti- mation of water needs taking into account the actual root surface. However, while the canopy cover measurement was relatively easy to carry out, it was much more difficult to determine the surface covered by the root system. Results obtained in the present work also show an over-estimation of water needs when the FAO method is adopted to estimate the evapotranspiration of young trees

Saline water use for vegetable crops production in smallholders farms

Field studies on saline water use (6 dS/m) for carrot, lettuce and pepper production in smallholder's farms were conducted in the arid region of Medenine-Tunisia. The irrigation regimes were full (FI) and deficit (DI-80, DI-60, FI-DI60) irrigated with levels of 100, 80 and 60% of ETc when 40% of total available water in the root zone in the FI treatment was depleted, and farmer method (Farmers). Results show that the greatest values of soil salinity were observed under farmer and DI-60 treatments. Relatively low ECe values were also recorded under FI-DI60 and DI-80 treatments. The highest mean yields of carrot (26.8-28.7-29.5 t/ha), lettuce (42.6-45.8 t/ha) and pepper (22.3-24.4 t/ha) were recorded for the FI treatment who is not significantly different with the FI-DI60 and DI-80 treatments. Compared with FI100, significant reductions in carrot, lettuce and pepper yields were observed under the DI60 and farmers treatments resulting from a reduction in yield components. The farmer’s method increased soil salinity and resulted in an increase of water use of 43-57% for carrot, 26-29% for lettuce and 11.5-16% for pepper. Water productivity (WP) values reflected the differences in yields and varied between 3.4 (Farmers) and 9.7 kg/m3 (DI-80) for carrot, 7.5 and 19.1 kg/m3 for lettuce and 2.4 and 5.5 kg/m3 for pepper across different years and treatments. The soil water balance-based irrigation method (FI) generated the greatest net income compared to the Farmers treatment in carrot, lettuce and pepper productions under arid environment and the lowest soil salinization. FI scheduling technique is suggested for optimizing saline water use for vegetable crops. Under water scarcity, the adoption of the FI-DI60 and DI-80 strategies results in 4.5 to 20% water savings as compared to FI with small impact on salinity in the root zone and yield and net income reductions

Здійснення адміністративно-територіальних реформ у місцях компактного проживання німців Криму в 20-30-х роках ХХ ст.

Статтю присвячено вивченню національної політики більшовиків у Криму на прикладі німців. Розкрито історію формування національних районів і селищних рад. Окремо розглянуто проведення більшовиками кадрової політики, динаміку розширення мережі національних сільських рад, проблеми переведення діловодства на німецьку мову. Показано, як сприймали німці національну політику радянської влади.Статья посвящена изучению национальной политики большевиков в Крыму на примере немцев. Раскрыта история формирования национальных районов и сельских советов. Отдельно рассмотрено проведение большевиками кадровой политики, динамику расширения сети национальных сельских советов, проблемы перевода делопроизводства на немецкий язык. Показано, как воспринимали немцы национальную политику советской власти.The article is devoted to the study of the national policy of the Bolsheviks in the Crimea on the example of the Germans. Reveals the history of the formation of national and rural councils. Separately, the Bolsheviks considered the holding of personnel policy, the dynamics of the expanding network of national rural councils, the problems associated with the transfer of proceedings in the German language. We show how Germans perceive the national policy of Soviet power

Dimensionnement et typologie d’une flotte de véhicules tenant compte de l’impact environnemental et de la maintenance

Nowadays, taking into account hard customer requirements, logistics represent one of the most important key of success for companies. It is clear that the expectations have led companies to explore new ways to improve their economic performance while respecting the imposed requirements. In this context, introducing the decision support tools taking into account operational and environmental constraints in the logistics field has become a major issue to turn up this challenge. Therein, we were interested in this research project in the economical sizing of a fleet of vehicles taking into account the environmental impact and maintenance, while considering two types of vehicles (fuel, electric). The operating mode, the energy consumption as well as the environmental impact caused by the means of transport are taken into account in presenting the various works studied. For the sizing and typology of a vehicle fleet based on maintenance and environmental impact we proposed three strategies, where each is illustrated through the development of an analytical model and a numerical resolution based on an example. The first relates to the strategy of acquisition and resale of all vehicles used at the end of missions, the second is about the strategy of leasing and the third concerns the strategy of acquisition, the subcontracting at the end of missions and resale at the end of the subcontracting contract. The optimization of each strategy is developed in order to determine the optimal number of vehicles of each type to be exploited, the duration of its use, and the preventive maintenance (PM) policy to be adopted for each types of vehicles. Numerical results show the differences between strategies and prove the robustness of the analytical models developed. We note that the impact of the period of health crisis (Covid-19) on the preventive maintenance strategy has been taken into consideration for the first strategy developed.De nos jours, la logistique occupe une place importante dans la politique de pilotage des entreprises. Ceci est dû certainement aux exigences imposées par la partie prenante. Ces exigences ont entrainé les entreprises à explorer d’autres voies pour améliorer leurs performances économiques tout en respectant les exigences imposées. La clé de la réussite de la plupart des entreprises réside dans la bonne décision à prendre avant d’investir. Dans ce cadre, instaurer des outils d’aides à la décision en tenant compte des contraintes opérationnelles et environnementales dans le domaine de la logistique est devenu un enjeu majeur pour relever ce défi. À cet égard, nous nous sommes intéressés dans ce projet de recherche au dimensionnement d’un parc de véhicules en tenant compte de l’impact environnemental et de la maintenance tout en considérant deux types de véhicules (diesel, électrique). Une étude bibliographique des domaines de la logistique de transport, la maintenance, les caractéristiques des différents types de véhicule, a été réalisée dans un premier temps. La modalité d’exploitation, la consommation énergétique ainsi que l’impact environnemental causé par les moyens de transport selon son type, sont pris en considération dans la présentation des différentes études menées. Pour le dimensionnement et typologie d’une flotte de véhicules basés sur la maintenance et l’impact environnemental on a proposé trois stratégies où chacune est illustrée par le biais du développement d’un modèle analytique et une résolution numérique basée sur un exemple. Le premier modèle se rapporte à la stratégie d’achat et revente en fin de missions, le deuxième s’intéresse à la stratégie de leasing et le troisième concerne la stratégie d’achat, sous-traitance en fin de mission et revente à la fin du contrat de sous-traitance. L’optimisation de chaque stratégie est développée dans le but de déterminer essentiellement le nombre de véhicules à exploiter dans chaque type, le nombre de mois d’utilisation de chaque véhicule et la périodicité de maintenance préventive pour chacun. Les résultats numériques montrent les différences entre stratégies et prouvent la robustesse des modèles analytiques développés. On note qu’on a pris en considération l’impact d’une période de crise sanitaire (Covid-19) sur le plan de maintenance préventive pour la première stratégie développée

Sizing and typology of a vehicle fleet taking into account the environmental impact and maintenance

De nos jours, la logistique occupe une place importante dans la politique de pilotage des entreprises. Ceci est dû certainement aux exigences imposées par la partie prenante. Ces exigences ont entrainé les entreprises à explorer d’autres voies pour améliorer leurs performances économiques tout en respectant les exigences imposées. La clé de la réussite de la plupart des entreprises réside dans la bonne décision à prendre avant d’investir. Dans ce cadre, instaurer des outils d’aides à la décision en tenant compte des contraintes opérationnelles et environnementales dans le domaine de la logistique est devenu un enjeu majeur pour relever ce défi. À cet égard, nous nous sommes intéressés dans ce projet de recherche au dimensionnement d’un parc de véhicules en tenant compte de l’impact environnemental et de la maintenance tout en considérant deux types de véhicules (diesel, électrique). Une étude bibliographique des domaines de la logistique de transport, la maintenance, les caractéristiques des différents types de véhicule, a été réalisée dans un premier temps. La modalité d’exploitation, la consommation énergétique ainsi que l’impact environnemental causé par les moyens de transport selon son type, sont pris en considération dans la présentation des différentes études menées. Pour le dimensionnement et typologie d’une flotte de véhicules basés sur la maintenance et l’impact environnemental on a proposé trois stratégies où chacune est illustrée par le biais du développement d’un modèle analytique et une résolution numérique basée sur un exemple. Le premier modèle se rapporte à la stratégie d’achat et revente en fin de missions, le deuxième s’intéresse à la stratégie de leasing et le troisième concerne la stratégie d’achat, sous-traitance en fin de mission et revente à la fin du contrat de sous-traitance. L’optimisation de chaque stratégie est développée dans le but de déterminer essentiellement le nombre de véhicules à exploiter dans chaque type, le nombre de mois d’utilisation de chaque véhicule et la périodicité de maintenance préventive pour chacun. Les résultats numériques montrent les différences entre stratégies et prouvent la robustesse des modèles analytiques développés. On note qu’on a pris en considération l’impact d’une période de crise sanitaire (Covid-19) sur le plan de maintenance préventive pour la première stratégie développée.Nowadays, taking into account hard customer requirements, logistics represent one of the most important key of success for companies. It is clear that the expectations have led companies to explore new ways to improve their economic performance while respecting the imposed requirements. In this context, introducing the decision support tools taking into account operational and environmental constraints in the logistics field has become a major issue to turn up this challenge. Therein, we were interested in this research project in the economical sizing of a fleet of vehicles taking into account the environmental impact and maintenance, while considering two types of vehicles (fuel, electric). The operating mode, the energy consumption as well as the environmental impact caused by the means of transport are taken into account in presenting the various works studied. For the sizing and typology of a vehicle fleet based on maintenance and environmental impact we proposed three strategies, where each is illustrated through the development of an analytical model and a numerical resolution based on an example. The first relates to the strategy of acquisition and resale of all vehicles used at the end of missions, the second is about the strategy of leasing and the third concerns the strategy of acquisition, the subcontracting at the end of missions and resale at the end of the subcontracting contract. The optimization of each strategy is developed in order to determine the optimal number of vehicles of each type to be exploited, the duration of its use, and the preventive maintenance (PM) policy to be adopted for each types of vehicles. Numerical results show the differences between strategies and prove the robustness of the analytical models developed. We note that the impact of the period of health crisis (Covid-19) on the preventive maintenance strategy has been taken into consideration for the first strategy developed

Perception of drought by farmers and its impact on farming and irrigation practices Perception of drought by farmers and its impact on farming and irrigation practices

------------------------------------------------------------------------------------------ To cite th is article / Pou r citer cet article Abstract. Climate change scenarios predict negative impacts on agriculture in the southern Mediterranean regions. Preparedness for increasingly frequent droughts requires a good knowledge on how chronic water shortages may affect production and cropping systems. This work investigates recent variations in agricultural production and in cropping practices in Tunisia as induced by a rapidly changing environment. Using production statistics and climatic records over the period 1984-2005, our analysis shows that variation of the agricultural production could be explained by the Standardized Precipitation Index (R² = 0.45), and that resilience to drought could be evaluated in the same manner. Data from surveys was used to identify adjustments adopted by farmers under the pressure of water scarcity in semi arid (Nabeul) and arid (Medenine) environments. Contrasting changes in cropping systems seem to be taking place for both regions. Contrast is also observed between irrigation strategies adopted by farmers. In Nabeul, large citrus growers having access to water from canal tend to over irrigate whenever water is available in order to minimize risks of water delivery failure from public networks. In contrast small farmers using shallow wells in Medenine seek practices such as deficit irrigation and intercropping in order to optimize water use. It is our view that options to face drought under increasing environmental stress should have a dynamic nature integrating adaptive practices used by farmers. Keywords. Climate change -Agriculture production -SPI -Water scarcity -Tunisia