Caractérisation des sols agricoles dans une région aride : cas de Mansoura (Ghardaïa)

Abstract

This study was conducted in the Saharan commune of Mansoura, in the south of the province of Ghardaïa, with the aim of characterizing the physicochemical properties of agricultural soils and assessing the impact of cropping systems on their quality. Using 48 soil samples collected from various types of agricultural land (cereals, olive trees, palm trees) and uncultivated control plots, several parameters were analyzed, including pH, electrical conductivity (EC), calcium carbonate (CaCO₃) content, organic matter (OM), and texture. The results revealed high spatial variability between the study sites. Soil pH was generally neutral to slightly alkaline (7.185 to 7.795), which is characteristic of arid environments, although there were differences between plots depending on agricultural practices. Electrical conductivity revealed moderate to high salinity levels (0.2885 dS/m to 8.595 dS/m), particularly in olive groves (8.595 dS/m), suggesting salt accumulation due to insufficiently controlled irrigation. CaCO₃ content (3.92% to 17.54%) varies considerably, reflecting a local geological influence, with higher levels in some areas with calcareous substrates. As for organic matter (2.13% to 3.10%), it is generally low, reflecting the low biological productivity of arid soils, but a few plots show a significant improvement where sustainable practices (organic amendments, crop rotations) are implemented. Texturally, the majority of soils have a sandy to sandy- clayey texture, which reduces their water and nutrient retention capacity, and poses a major constraint to the sustainability of agricultural systems. Overall, the results confirm that soil quality in this region is strongly influenced by agricultural practices and highlight the urgent need to adopt sustainable management strategies to preserve soil fertility, optimize water use, and improve the resilience of agroecosystems to the extreme climatic conditions specific to arid zones.