Controlling runoff generation and soil loss from field experimental plots through inoculating cyanobacteria

Abstract

Controlling runoff generation and soil loss from hillslopes is a priority for land management. The capability of cyanobacteria as inoculants has recently been utilized in land management, and as a result various lab-scale studies have been conducted. The present study conducted a field-pilot experiment in Miandoab City, south of West Azerbaijan Province, North West Iran, to evaluate the success of cyanobacteria inoculation in runoff and sediment reduction from an abandoned and degraded land at large plot scale under natural rainfall. On 26 December 2017, the cultured native cyanobacteria (Nostoc sp. and Oscillatoria sp.) was inoculated on the 22.1 × 1.83 m2-plot in three replicates along with three control plots treated by pure water. The runoff and soil loss from the treated plots were measured for seven rainfall events that produced runoff during normal rainy season of the study area i.e., December 2017 to May 2018. Results showed that inoculation of cyanobacteria significantly (p < 0.05) decreased runoff by some 35, 25, 31, 33, 46, 47, and 57% for the recorded rainfall events (1 to 7), respectively. The beneficial reduction of sediment concentration due to the inoculation of cyanobacteria was also observed for rainfall events 1, 2, 3, and 5 at the respective tune of 16, 34, 36, and 135% compared to those of control plots. Soil cracks indicators, roughness, and aggregate stability were also improved by 5.1 to 27%, 14 to 20%, and 13 to 22%, respectively, owing to the inoculation of cyanobacteria. Although vegetation cover at the end of experiment was 2.6 times denser than that in the beginning, there was no significant difference between inoculated and control plots. By and large, field inoculation of cyanobacteria was found as an efficient technique for runoff and soil loss inhibition, particularly in degraded and abandoned drylands.