The impact of cyanobacteria inoculation on soil hydraulic properties at the lab-scale experiment

Ecosystem-based approaches, including soil inoculation, have been considered to improve the soil water behavior, for the purpose of ensuring better irrigation management on farms. This study was, therefore, conducted to assess the responses of the moisture characteristic curve (MCC) and saturated hydraulic conductivity (SHC) to soil inoculation with cyanobacteria. To this end, the most suitable existing cyanobacteria (i.e., Nostoc sp. and Oscillatoria sp.) from the original soil were inoculated on clay, loam and sand textures at a small cylinder scale. After 35 days, the MCC and SHC of the treatments (six control and inoculation treatments in three repetitions) were measured using the sandbox and pressure plate, and constant head method, respectively. The results showed that, in the control treatment, the volumetric water content of the clay, loam and sand textures was 38–69%, 28–58% and 8–24%, respectively. Meanwhile, the inoculation of cyanobacteria led to a significant (P < 0.05) increase in the MCC of the loam and sand soils; their values were 36–65% and 16–31%, respectively. In the control, the SHC of the clay, loam and sand textures was 0.42, 0.54 and 1.21 cm min−1, respectively; meanwhile, this was 0.37, 0.50 and 0.67 cm min−1 for the inoculated treatments, respectively. On the other hand, the inoculated cyanobacteria reduced the SHC of the sand soils by 44%. We also found that the inoculated cyanobacteria perceptibly improved the soil surface physical and chemical properties, which could play a key role in determining the soil hydraulic and hydrologic behavior. Overall, we found that soil inoculation with cyanobacteria could be an effective approach in improving the soil water behavior, especially in coarse texture soils; thus, it could serve as a suitable irrigation and drainage management method in agricultural lands.