Short-term effect of organic residue incorporation on soil aggregate stability along gradient in salinity in the lower cheliff plain (Algeria)

A field experiment was performed to examine the effectiveness of adding two kinds of organic materials (wheat Straw and cattle manure) on the soil aggregate stability along a gradient in salinity in the lower cheliff plain (western Algeria). The experiment was set up in a factorial design by complete randomized blocks with three replicates. The treatments were applied at a rate of 4 g C kg-1 soil. One year after organic amendments, mean weight diameter (MWD) was measured using the Le Bissonais method (1996). Other soil properties involved in saline soil aggregation were also measured, namely, electrical conductivity (EC), exchangeable sodium percentage (ESP), pH, cation exchangeable capacity (CEC), porosity, saturated hydraulic conductivity (Ksat), microbial biomass carbon (MBC) and hot water extractable polysaccharide (HWEP). The resultsdemonstrated a significant effect of organic inputs in improving aggregate stability; the effectiveness was related to the type of aggregate stability test that has been used, organic matter type and the level of soil salinity. The wheat straw proved to be more efficient in soil aggregation than cattle manure. Most of the considered soil properties were significantly influenced by organic inputs. Overall, correlation analysis revealed that enhanced microbial biomass was the most important factor in stabilizing soil aggregates (r = 0.72 with MWDMB and r = 0.64 with MWDFW). Therefore, MWD influences soil porosity (r = 0.67 with MWDMB and r = 0.56 with MWDFW), which in turn resulted in increased hydraulic conductivity (r = 0.77 with MWDMB and r = 0.87 with MWDFW).   Key words: Wheat straw, cattle manure, soil salinity, aggregate stability, soil properties.