Shahid Bahonar University of Kerman and Iranian Biotechnology Society Agricultural Biotechnology Journal 2228-6705 18 3 2026 08 23 The effects of adding Vertisol conditioners and emulsified Lubricating oil on soil respiration and biological soil crust thickness in sandy soil under different rainfall and moisture treatments The effects of adding Vertisol conditioners and emulsified Lubricating oil on soil respiration and biological soil crust thickness in sandy soil under different rainfall and moisture treatments 355 372 5437 10.22103/jab.2026.27141.1892 FA Duha Salem Jamil Department of Soil Sciences Water Resources, College of Agriculture, University of Basra, Iraq 0009-0000-0595-0978 Ali Hamdhi Dheyab Department of Soil Sciences Water Resources, College of Agriculture, University of Basra, Iraq 0000-0003-3636-4490 Dakhil Radhi Nedawi Department of Soil Sciences Water Resources, College of Agriculture, University of Basra, Iraq 0000-0002-8647-9459 Journal Article 2026 05 09 ObjectiveThe aim of this study was to investigate the effect of adding natural and industrial soil conditioners on the effectiveness of microorganisms and the thickness of the biological crust.Materials and methodsIn the field experiment, a section of the soil surface was cut to a depth of 15 cm Measurements were taken in the middle and end of the experiment. The experiment included two factors. The first factor was conditioner factor in seven treatments. The second factor was the rainfall moisture treatment, included four treatments.ResultsSoil conditioner treatments significantly increased soil respiration compared to the control. Lubricating oil treatment (O3) and vertisol soil treatment (C3) showed the highest CO2 release. The release rates for them were 29.13 and 27.03 mg CO2/kg soil, respectively. Among the rainfall moisture treatments, R1 showed the highest respiration rate (26.24 mg CO2/kg soil). While the lowest value was observed in R3 (19.79 mg CO2/kg soil). Soil amendments also significantly increased the biological crust thickness compared to the control group (C0). Among them, the O3 treatment showed the highest crust thickness in the middle and end of the experiment (4.66 and 4.81 cm, respectively). After that, the C3 treatment recorded the highest thickness (3.15 and 3.24 cm). It should be noted that the control treatment (C0) recorded the lowest values (1.36 and 1.40 cm). The highest recorded value for crust thickness, in terms of rainfall moisture, was related to treatment R1 and showed a significant difference with treatments R2, R3 and R4. ConclusionUsing soil conditioners, particularly lubricating oil and Vertisol, significantly increased microbial activity and biological crust development. In addition, higher moisture levels improved soil respiration and crust formation. The results of this study showed that soil amendments and moisture management are of great importance in improving the biological properties of soil and should be considered. ObjectiveThe aim of this study was to investigate the effect of adding natural and industrial soil conditioners on the effectiveness of microorganisms and the thickness of the biological crust.Materials and methodsIn the field experiment, a section of the soil surface was cut to a depth of 15 cm Measurements were taken in the middle and end of the experiment. The experiment included two factors. The first factor was conditioner factor in seven treatments. The second factor was the rainfall moisture treatment, included four treatments.ResultsSoil conditioner treatments significantly increased soil respiration compared to the control. Lubricating oil treatment (O3) and vertisol soil treatment (C3) showed the highest CO2 release. The release rates for them were 29.13 and 27.03 mg CO2/kg soil, respectively. Among the rainfall moisture treatments, R1 showed the highest respiration rate (26.24 mg CO2/kg soil). While the lowest value was observed in R3 (19.79 mg CO2/kg soil). Soil amendments also significantly increased the biological crust thickness compared to the control group (C0). Among them, the O3 treatment showed the highest crust thickness in the middle and end of the experiment (4.66 and 4.81 cm, respectively). After that, the C3 treatment recorded the highest thickness (3.15 and 3.24 cm). It should be noted that the control treatment (C0) recorded the lowest values (1.36 and 1.40 cm). The highest recorded value for crust thickness, in terms of rainfall moisture, was related to treatment R1 and showed a significant difference with treatments R2, R3 and R4. ConclusionUsing soil conditioners, particularly lubricating oil and Vertisol, significantly increased microbial activity and biological crust development. In addition, higher moisture levels improved soil respiration and crust formation. The results of this study showed that soil amendments and moisture management are of great importance in improving the biological properties of soil and should be considered. https://jab.uk.ac.ir/article_5437_0a3b6f64f0523984e51323fe53b8c504.pdf