The Effect of Winter Olive and Apricot Leave Residues on Soil Structural Stability using HEMC Method in Different Soil Salinity Levels

Soil improvement with plant residues incorporation influences many soil properties. This study was conducted to investigate the effect of apricot and winter olive leaves (0, 1 and 3 g residue 100g-1 soil) on the soil structural stability using high energy moisture curve (HEMC) method in different soil salinity levels (1, 5 and 10 dS m-1). Apricot residues increased the soil organic carbon content and diluted acid carbohydrates and decreased the soil basal respiration more than the winter olive leaves. Increasing residues and salinity levels have also increased the soil organic carbon and the carbohydrates concentration in the soil. Also, the soil basal respiration has been reduced by increasing salinity. There were no significant differences between the apricot and winter olive residues in terms of their effectiveness on the soil drainable porosity (VDP), the soil suction in inflection point (τd) and the stability index (SI) in slow wetting method. However, the apricot leaves increased the soil drainable porosity and the stability index more than the winter olive in fast wetting method. This finding shows the different response and the structural instability of the soil for the two proposed organic matters. Plant residues increment by improving soil carbon and carbohydrates concentration, and salinity increment by improving divalent cation concentration have enhanced the soil stability ratio and the soil VDP ratio in both; fast and slow wetting methods. The results of this study showed that the application of native crop residues in the soils with low organic matter could improve the soil physical characteristics and these changes probably recover the soil physical fertility in the long term application.