Reducing soil and water loss through stimulation of degraded biological soil crusts bacteria in experimental small plots

  Achieving to sustainable development is not possible without soil and water resources conservation and land degradation reducing. On the other hand, in the low density-vegetation lands, biological soil crusts induced by soil micro-organisms' activities play an important role in conserving and improving of soil stability. However, in degraded lands, biological soil crusts are less developed. Thus, recently, biological soil crusts restoration by providing the appropriate conditions for increasing soil micro-organisms' activities have been further considered through the new biotechnologies applying such as soil micro-organisms stimulants. However, the quick and sustainable effectiveness of applying soil conservation strategies is the most important criteria in the selection of managerial practices. Hence, this study was planned to assess performance of a soil bacterial stimulant nutrient (named B4) as completely bio-amendment in reducing soil loss and runoff at laboratory and small plots conditions. In the study, the experimental plots were filled by collected soil of degraded and erosion-prone area of Marzanabad-Kandelus region based on the layering, grain size and bulk density of the native soil area. The solution with 15 g calcium acetate l-1 distilled water (dw), four g yeast extract l-1 dw, and five g dextrose l-1 dw was prepared as B4 stimulant nutrient. Then the B4 was spraied on plots. To this end, two treatments of B4 injection and control with three replications were considered. After 15 days, in the Rain and Erosion Simulation Laboratory of Tarbiat Modares University, the simulated rainfall was carried out with during of 100 min and intensity of 50 mm h-1 according to high-erosive rainfall of the native area. Then, the soil loss and runoff components were measured. Statistical comparison of results indicated that injection of B4 stimulant nutrient improved the soil loss and runoff components through stimulate proliferation of soil bacteria and its adhesion and productivity properties. The start time and time to peak of runoff at the control plots (without injection) were increased significantly (p<0.05) from 24.83 to 49.22 min and from 78.66 to 92.66 min at the stimulant nutrient plots, respectively. As well as, volume and peak of runoff, soil loss and sediment concentration at the stimulant nutrient plots were decreased significantly (p<0.05) and about 88, 92, 95 and 35%, respectively in compared to control. So that, the volume and peak of runoff, soil loss and sediment concentration at the stimulant nutrient treatment were measured about 275.66 and 18.66 mm, 0.49 g and 1.79 g l-1, respectively. According to our results, the restoration and enhancement of biological soil crusts in low density-vegetation and degraded lands through stimulating and increasing population of soil micro-organisms induced by stimulant nutrient founded as an efficient, quick and bio-strategy to conserve soil and water resources. However, further researches are required to achieve reliable strategies by using other microbial stimulants and evaluating their durability under consecutive precipitation and time passing