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

Soil is a crucial component of ecosystem function and productivity in rangeland areas. Cyanobacteria, as one of the living microorganisms in soil, play an essential role in increasing soil fertility by fixing nitrogen and carbon. In this study, we aimed to investigate the effect of different concentrations of cyanobacteria on soil fertility in Golgangak rangelands in Jamabroud watershed and determine the optimal concentration of cyanobacteria to improve soil fertility.

We collected cyanobacteria from the soil surface horizon (0-2cm deep) and identified three dominant genera of cyanobacteria, including Nostoc, Phormidium, and Osillatoria. We prepared three different concentrations of cyanobacteria, including 1012, 1010, and 108 cyanobacterial cells per liter of BBM suspension and sprayed them directly into the field. We evaluated soil fertility factors, including nitrogen, potassium, organic carbon, and pH, by resampling soil samples at 15, 30, 45, and 180 days after inoculation.

The results showed a significant relationship (p <0.05) between control and inoculation plots. Nitrogen, potassium, and organic carbon showed an increase of about 21.3%, 51.3%, and 51.3%, respectively, at the end of the experiment, while pH decreased by 0.4. The concentration of 108 liters was determined to be the optimal concentration to improve soil fertility in terms of nitrogen, potassium, and organic carbon.

Our findings suggest that spraying cyanobacteria in Golgangak rangelands can increase soil fertility factors. The concentration of 108 liters was determined to be the optimal concentration to improve soil fertility in terms of nitrogen, potassium, and organic carbon. This research can be considered as the first step in investigating the possibility of using effective and fast environmental methods to improve soil fertility in different ranges, especially degraded ranges. However, it is crucial to determine the optimal concentration of cyanobacteria for each range to ensure the effectiveness of corrective measures.