Abstract

The origins and spatial variability of salinity within irrigated plots are a constraint to good long-term field management. Regional depletion of groundwater resources, as well as soil salinization, have been reported in the Tadla plain, a key production area in Morocco. In the northwestern part, water supply is provided only by the local water table, whose evolution in level and salinity over the last 24 years has been analyzed. A mapping of 17 plots was carried out by electromagnetic induction (EC_a) after calibration of the measurements with salinity (R² = 0.94). These plots are cultivated with different crops (wheat, olive, sugar beet, alfalfa, carrots) with little or no crop rotation, or left fallow. The results highlight two main factors of salinization. On the one hand, the type of crop leads to salinization that increases according to water needs, which are rarely satisfied, thus favoring the accumulation of salts in the upper part of the soil profile. This first factor explained 80 to 85% of the variance in EC_a measurements. On the other hand, the gravity irrigation method associated with numerous leaks is responsible for an unequal distribution of water within the plots, associated with 15–20% of the variance. These results confirm the current unsustainable management of this hydro cultural system and highlight the need for better access to quality water and improved irrigation technology. A development proposal is briefly presented.

摘要

灌溉地块内盐度的起源和空间变异性是良好长期田间管理的制约因素。据报道，摩洛哥的主要产区塔德拉平原出现了地下水资源的区域枯竭以及土壤盐碱化。在西北部，供水仅由当地地下水位提供，对其过去 24 年的水位和盐度演变进行了分析。在_用盐度 ( R ²= 0.94)。这些地块种植了不同的作物（小麦、橄榄、甜菜、紫花苜蓿、胡萝卜），很少或没有轮作或休耕。结果突出了盐渍化的两个主要因素。一方面，作物类型导致盐渍化，根据需水量增加，很少得到满足，因此有利于盐分在土壤剖面的上部积累。_{第一个因素解释了 EC a}中 80% 到 85% 的差异测量。另一方面，与大量泄漏相关的重力灌溉方法是造成地块内水分布不均的原因，与 15-20% 的方差相关。这些结果证实了目前对该水文养殖系统的不可持续管理，并强调需要更好地获得优质水和改进灌溉技术。简要介绍了开发建议。