In Tunisia, water used for irrigation is often saline, increasing the risk of salinization for soils and crops. In this study, an experiment was conducted on a tomato crop cultivated on a silty-clay soil irrigated with three different water qualities: 0, 3.5, and 7 dS·m⁻¹. Experimental data were then used to calibrate and validate the Hydrus-1D model, which simulates water flow and salt transfer in soils. The successfully-calibrated and validated model was then used to study the combined effects of the soil osmotic and soil matrix potentials on root water uptake. The values of the root mean square error (RMSE), the coefficient of determination (CD), the modeling efficiency (EF), and the coefficient of residual mass (CRM) were close to their optimal values for both soil water content and soil electrical conductivity profiles, indicating the reliability of the model to reproduce water and salt dynamics. Relative yields (Y_r), indirectly estimated using actual and potential root water uptake (transpiration), indicated that the multiplicative stress response model (using the S-shape model) satisfactorily simulates measured yields and reproduces the effects of irrigation with saline waters on crop yields. An alternative scenario using a reduction of water requirements by 50% was investigated to assess an irrigation method with considerable water savings. As the results show that relative yields, Y_r, were only slightly reduced, the crop water requirements estimated by CROPWAT 8.0 must have been overestimated. The variation of the soil salinity in the root zone highlighted a high salinization risk in the short-term when water of 7 dS·m⁻¹ is used for irrigation.

Effect of sprayer parameters and wind speed on spray retention and soil deposits of pesticides: Case of artichoke cultivar | Hassouna Bahrouni, Hanene Chaabane, Nidhal Marzougui, Sana Ben Meriem, BCHINI Houcine, Mohamed Ali BEN ABDALLAH | Agricultural Journals

Environment pollution related to pesticides has been confirmed by the scientific community for a long time, but the available information on the impact of this phenomenon on human health and the ecosystem are still insufficient. Contamination of the environment can occur through various pathways, ground deposits during the application of pesticides to crops are one of those pathways. The retention rate of sprayed droplets is an important factor both for the efficacy of the phytosanitary treatment and the quantities of lost pesticides on the ground. This paper presents an overview of factors that affect spray droplet behavior, involved process in sprayed drop fate and the mainly techniques for measuring pesticide deposits to the ground and plant retention. We present studies that have focused on pesticide retention and soil deposition during crop spraying in relation to sprayer equipment, used formulation and climatic factors. Plant retention and pesticide deposits during spray is a complex problem depending mainly on physical sprayer parameters, climatic conditions, spray properties and chemical formulation. By illustrating the large variety of analytical methods during the recently years, it aims to explain that it is always possible to assess the impact of pesticides in all compartments of the environment. The use of concerned molecules and natural collectors is the safest to evaluate the real situation, but the use of tracers and artificial targets is both very reported and safety for the environment.

Three field experiments were conducted in the plot of Technical Centre for Potato and Artichoke during three cropping season 2009, 2010 and 2011.The objective of this research is to evaluate the effect of the partial root-zone drying irrigation technique (PRD) on the dry matter, yield, water consumption and water use efficiency of potato (Spunta Variety). Four treatments were applied from the initiation of tuberisation stage to potato harvesting: FI treatment received 100% of Etc; PRD80, PRD70, and PRD60 treatments received respectively: 80, 70 and 60% of FI at each irrigation event and it was shifted between the two sides of the plants every 2 to 10 days. The highest water consumption was observed in FI as 336.5, 376, and 341.8 mm in the 2009, 2010 and 2011 respectively, and the lowest was found in PRD60 as 280.4, 294.5, and 256.1 mm in the 2009, 2010 and 2011 respectively. The maximum tuber yield was obtained from the FI as 25.6, 42.9 and 39.1 tha-1, in the 2009, 2010 and 2011 respectively. There was no significant difference between FI and PRD60 with respect to tuber yields (LSD 5%).The highest water use efficiency (WUEY) was found in PRD60 as 13.4 kg m-3, in the second experiment (2010) and the lowest was found in PRD80 as 6.8 kg m-3 in the first experiment (2009). In the other hand, a linear relation between the accumulated total dry matter and the accumulated water consumption was able to be revealed.

The irrigated areas in Tunisia were esteemed in 2010 to over 420 thousand hectares and represents 8% of farmland, this little area providing 35% of the total crop production. This situation makes it exert enormous pressure on the irrigated sector that his intensification is very associated to increased inputs including especially pesticides. However, the irrational use and abuse of pesticides associated with an inadequate irrigation system management are a great threat of contamination to groundwater resources and constitute one of the greatest challenges facing Tunisian government today. According to FAO, 2013, the adoption of the concept of best practices can meet this challenge. These best practices are not only a practice that are best, but a practices that have been proven to work well and produce good results, and are therefore recommended as a model. This paper aims to analyze in a framework of global environmental approach, the role of the best irrigation practices (BIPs) to reduce environmental impact on groundwater resource. Finally, it was proposed a set of best irrigation practices completed by the technical recommendations for limiting the environmental impact of pesticide in groundwater resource.

En Tunisie, comme dans plusieurs pays méditerranéens, la céréaliculture est une activité très consommatrice de pesticides, (63% de la consommation totale de l'agriculture tunisienne). Par conséquent, il est nécessaire d'étudier le devenir des pesticides appliqués afin de réduire les quantités perdues dans l'environnement tout en maintenant un niveau acceptable de l'efficacité des traitements. Plusieurs études ont montré qu'après leur éjection par la buse, les gouttes sont plus ou moins soumises aux phénomènes de dérive et de perte au sol pendant l'application. La partie principale de ce travail est basée sur le développement et la validation d'un modèle capable de calculer les dépôts, la volatilisation, (évaporation et pertes vers l'air) sous le vent, en grandes cultures. Le modèle DriftL a été alors construit sous le logiciel SciLab, version 5.03. Il a été calé à partir de mesures réalisées sous des conditions contrôlées en soufflerie et a bénéficié d'une validation expérimentale. Une deuxième partie a étudié expérimentalement les pertes directes au sol et la rétention sur les plantes en conditions de laboratoire. Comme le travail mené en soufflerie, elle a permis de mettre en évidence une relation entre la granulométrie de la pulvérisation, la hauteur des buses, les variables microclimatiques et les dépôts mesurés dans les compartiments air, sol et plante. Pour effectuer les mesures, une démarche expérimentale a été mise en place afin de choisir la méthode de travail. Après de nombreux tests, un collecteur a été sélectionné pour chaque compartiment. Une rampe mobile a été également fabriquée pour jouer le rôle du pulvérisateur dans les conditions de laboratoire. Les mesures effectuées au champ ont permis de valider des calculs de DriftL et des résultats obtenus au laboratoire