Effectiveness of Granular Polyacrylamide to Reduce Soil Erosion During Consecutive Rainstorms in a Calcic Regosol Exposed to Different Fire Conditions

Abstract

Fire severity varies widely among and within wildfires. The objective of this work was to test the effectiveness of granular polyacrylamide (PAM) to reduce erosion in a Calcic Regosol exposed to different fire conditions. Three treatments were selected representing disturbances that coexist after a wildfire: unburned, low-moderate severity direct fire, and prolonged heating under moderate temperature [heated (HT)]. Granular PAM was spread on the surface of disturbed samples at two rates: (i) 0 (control) and (ii) 50 kg ha À1 . Additional application rates of 25 and 100 kg ha À1 were tested in HT. Three 80-mm rainstorms were applied with an intensity of 47 mm h À1 , separated by drying periods. PAM reduced soil loss in all storms in unburned and direct fire, although runoff increased during the first storm due to increased runoff viscosity. In the highly stable HT, soil loss was reduced only with an application rate of 100 kg ha À1 and after a drying period. In many cases, granular PAM could be effective to reduce post-fire erosion. In soils with high structural stability, a PAM dose should be selected to find a right balance between its stabilising effect on soil structure and its effect increasing runoff during the first storm.

Effectiveness of Polyacrylamide, Wood Shred Mulch, and Pine Needle Mulch as Post-Fire Hillslope Stabilization Treatments in Two Contrasting Volcanic Soils

“…Runoff and interrill erosion values were significantly higher than those reported for undisturbed Andisols [15,24,25], but still considerably lower than those of volcanic soils affected by high soil burn severity [8,14,15] or other fire-affected soil types from the Mediterranean area [9,26,27], Northwestern Spain and Portugal [9,10,28], Western USA [4,5,8] and Australia [29,30]. Differences between this study and the previous work listed above can be explain by a number of other factors.…”

“…In line with their results on runoff, Davidson et al [11] reported a significant decrease in soil water repellency after the application of PAM and suggested that PAM molecules could be interacting with hydrophobic coated soil particles that flocculate and open interstitial channels that increase water infiltration. Other studies [9,27], however, reported a significant increase in runoff and a decrease in sediment delivery during the first storm after the application of PAM to wettable soils using rainfall simulations. The authors attributed the results regarding erosion to the aggregating effect of PAM and the results on runoff to the reduction of infiltration rate due to the increase in water viscosity when the PAM was dissolved.…”

“…This is probably because in this kind of soils the essential interaction between PAM and soil particles to increase aggregation or decrease water repellency is limited to a few preferential pathways where the infiltration takes place and not generally distributed across the soil surface. Lado et al [27] reported that the reduction in infiltration was reverted in the second and successive simulated rain events due to the enhanced aggregate stability triggered by the interaction of dissolved PAM molecules and soil particles during the infiltration process. It is unclear whether this effect can be expected in an extremely water-repellent soil such as the one examined at Vilaflor due to the limited infiltration and interaction between PAM and soil.…”

Advances towards an Integrated Assessment of Fire Effects on Soils, Vegetation and Geomorphological Processes

“…Regarding some new advances in the application of mitigation techniques to post‐fire environments, Lado et al . (, this issue) present a laboratory investigation into the effectiveness of granular polyacrylamide (PAM) to reduce erosion in soils exposed to different fire conditions (unburned, low‐moderate severity fire and prolonged heating under moderate temperature). Granular PAM effectively reduced post‐fire erosion.…”

Photo‐mediated metal free atom transfer radical polymerization of acrylamide in water

“…Polyacrylamide (PAM) is one of the most widely used water‐soluble polymers in the field of soil conditioner, wastewater treatment, the cosmetic, paper, biomedical applications, and textile industries, etc. In industry, PAM and its derivatives are obtained by the free radical polymerization .…”