No abstract

No abstract

In semi-arid and arid areas, soil salinity has adverse effects both on the environment and agricultural production. The main causes of this salinization come from natural or anthropogenic processes, which is certainly an environmental problem that affects more than 20% of the world's land. This study was made in order to map the spatial distribution of soil salinity of the irrigated perimeter of El Ghrous in southeastern Algeria. These maps were performed based on data collected from 190 soil samples from 0 to 15 cm deep. We used ordinary kriging (OK) to analyze the spatial variability of soil salinity, while indicator kriging (IK) was used to analyze salinity versus threshold values. The salinity map predicted by the electrical conductivity (EC) values using the ordinary kriging (OK) method showed the different classes of salinity according to Durand's classification with moderately saline 3rd order dominance, while the unsalted soil (EC < 0.6 dS m^-1) represents a very low percentage (1.5%). The indicator kriging (IK) was carried out by four thresholds which correspond to the salinity class limits: EC > 0.6, EC > 1, EC > 2, EC > 3, and EC > 4 dS m^-1, for developing probability maps to determine risk areas. This study has shown the spatial trend of soil salinity by geolocation of different classes, and to carry out risk maps using geostatistical techniques.

The main goal of this study was to identify the problems that are putting the viability of watering ponds at risk. For doing that, we have analyzed five different study cases: (I) livestock consumption, Mediterranean climate (rangelands of SW Spain), (II) multifunctional ponds (Arroyo de la Luz, Spain), (III) ecotourism (Valdepajares de Tajo, Spain), (IV) crop irrigation and fish farming, semi-arid climate (the wilaya of Ouargla, Algeria), and (V) livestock consumption, humid subtropical climate (Prudentópolis, Brazil). The identification of problems was made through surveys, personal interviews, local knowledge and literature review as well as through the analysis of water quality parameters such as the concentration of phosphates and fecal coliforms in some ponds. We have identified problems of water shortage (ca. 50% of rangeland farmers), pollution induced by agriculture (maximum values of phosphates = 1.33 mg L−1) and livestock farming (maximum value of fecal coliforms ≈ 7000 cfu mL−1), low potability for human consumption (score: 2.8/7.0), invasive species such as Azolla filiculoides (10 out of 17 watering ponds), high water temperature for aquaculture in summer (Algeria) and the increase of turbidity in nearby water courses due to the actions of free-fattening pigs (Brazil), among many other problems. We conclude an extra effort by stakeholders is still needed in order to agree mitigation strategies.

No abstract