Determination of the best concentration of cyanobacteria to improve soil fertility in rangeland (Case study: Jamabroud catchment)

Cyanobacteria play an important role in increasing soil fertility as one of the biological soil crust in rangelands. They have a significant effect on improving soil fertility because of nitrogen and carbon fixation. In this study, the effect of different concentrations of cyanobacteria as one of the soil biomasses and finally to determine the best concentration for optimizing soil fertility in Golgangak rangelands in Jamabroud watershed was investigated. For this purpose, cyanobacteria were first collected by sampling soil surface horizons (0-2cm deep) and purified under laboratory conditions. This purification continued to the genus, and finally three dominant genera of cyanobacteria were identified, with priority being Nostoc, Phormidium, Osillatoria. Subsequently, three different concentrations of cyanobacteria including 1012, 1010 and 108 cyanobacterial cells were prepared per liter BBM suspension and sprayed directly into the field. Soil samples were re-sampled at 15, 30, 45 and 180 days after inoculation and fertility factors (Nitrogen, Potassium, Organic Carbon, pH) were evaluated. Results showed a significant relationship (p <0.05) between control and inoculation plots. Nitrogen, potassium, organic carbon showed an increase of about 21.3%, 51.3%, 51.3% at the end of the experiment, respectively, and a pH decrease of 0.4. Finally, 108 L concentration was determined as the best concentration to improve soil condition in the rangeland.