Salinity patterns in irrigation systems, a threat to be demystified, a constraint to be managed: Field evidence from Algeria and Tunisia

Abstract

Salinity problems induced by irrigation are often presented in the literature as a threat that can only be managed at the irrigation scheme scale by installing subsurface drainage. On the other hand, salinity is a constraint that has often been successfully managed locally by farmers adapting their practices. However, the continuing expansion of irrigation with related water scarcity problems plus the increasing use of groundwater of marginal quality has resulted in a new challenge that is difficult to handle at the farm level only. To assess the dynamics of soil salinity and water quality together with farmers' salinity management practices, we adapted a common approach to analyze two contrasted salinity patterns: a traditional salinity pattern in an oasis (Fatnassa, Tunisia), and a recent sodicity pattern in a large irrigation scheme (Lower Chelif, Algeria). This approach which combines surveys on farmers' perceptions and practices and salinity measurements and geochemical analysis paves the way for more integrated management of salinity problems related to water scarcity. Copyright # 2009 John Wiley & Sons, Ltd. un processus de sodisation (plaine du Bas-Chelif, Algérie). L'utilisation de cette approche qui combine des enquêtes sur les perceptions et les pratiques des agriculteurs, des mesures de salinité et des analyzes géochimiques ouvre des perspectives pour une vision et une gestion plus intégrée des problèmes de salinité liés à la pénurie d'eau.

Groundwater in Irrigation Systems: From Menace to Mainstay

“…In North Africa, Bouarfa et al . () and Ghazouani et al . () showed that farmers are able to mitigate the effect of salinity on agricultural production through a host of appropriate agricultural practices.…”

“…However, the drainage community should place drainage issues in the new context of irrigated agriculture, in which farmers are the main actors of the drainage processes due to their massive use of individual tubewells and in which techniques that save irrigation water are spreading rapidly. In such a context, waterlogging is no longer a fatality and farmers generally adapt their practices to deal with salinity (Bouarfa et al , ). In Figure , we provocatively assume that the general trend of a groundwater level is towards a decrease.…”

“…The latter problem cannot be cured by leaching and drainage only (Jayawardane and Chan, 1994). In North Africa, Bouarfa et al (2009) and Ghazouani et al (2009) showed that farmers are able to mitigate the effect of salinity on agricultural production through a host of appropriate agricultural practices. Finally, some authors also tried to identify other solutions for salinization, such as developing salt-tolerant crops through genetics: 'By itself, the traditional engineering approach to the problem is no longer adequate' (Epstein et al, 1980).…”

Changes in weed species composition in irrigated agriculture in Saharan Algeria

“…Salt is a result of the high evaporation rate characterising arid and semiarid climates, an effect that causes salt to accumulate in the top layer of the soil (Al-Amoud, 2010). It can also come from irrigation with marginal groundwater resources and from a rise in the water table (Bouarfa et al, 2009).…”

“…While palm tree plantations used to be well-drained, there is now a lack of maintenance of drainage systems, which combined with the water table rise, makes soils wetter. Also, the water from the water table is increasingly salty and salt gradually accumulates in the soil over time (Bouarfa et al, 2009). Therefore, with time, weed flora characterising humid and salty soils and consisting of such species as C. cretica, C. rotundus and P. australis has colonised the area.…”