Evaluating the effectiveness of agricultural mulches for reducing post-wildfire wind erosion

Authors: ROBICHAUD, PETE - Us Forest Service (FS); JENNEWEIN, JOTI - Us Forest Service (FS); Sharratt, Brenton; LEWIS, S - Us Forest Service (FS); BROWN, B - Us Forest Service (FS)

Submitted to: Aeolian Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2017
Publication Date: 5/30/2017
Citation: Robichaud, P.R., Jennewein, J., Sharratt, B.S., Lewis, S., Brown, B. 2017. Evaluating the effectiveness of agricultural mulches for reducing post-wildfire wind erosion. Aeolian Research. 27:13-21.

Interpretive Summary: Innovative techniques for managing burned lands in arid and semiarid regions are needed to control post-fire wind erosion. The application of rice or wheat straw to the surface of burned soils effectively controlled wind erosion, but only at low wind speed. Rice and wheat straw were very mobile and thus did not reduce wind erosion at high wind speed. However, the use of a tackifier stabilized the straw and reduced wind erosion at high wind speed. Our findings suggest that the Forest Service, Bureau of Land Management, and private land managers may reduce post-fire wind erosion by applying straw, and securing the straw with a tackifier, after wildfires.

Technical Abstract: Post-wildfire soil erosion can be caused by water or aeolian processes yet most erosion research has focused on predominantly water-driven erosion. This study investigates the effectiveness of three agricultural mulches, with and without a tackifier, on aeolian sediment transport processes. A wind tunnel was used to simulate post-wildfire wind erosion at three wind speeds (6, 11 and 18 m s-1). Shallow trays containing soil collected after a wildfire were treated with rice, wheat or chopped wheat mulch at two cover percentages (10% and 70%) and three dilutions of tackifier (water to tackifier ratios of 1:6, 1:3, and 1:0). The mulch treatments were easily moved at all wind speeds often leaving bare soil surface with cover reductions upwards of 90% for the duration of the experimental runs. As expected, sediment loss was greatest for the bare soil treatment, ranging from 6.5 g m-2 at the lowest wind speed to 6258 g m-2 at the highest wind speed. Adding wheat or chopped wheat mulch significantly reduced sediment loss by factors of 10 to 20 (698 and 298 g m-2, respectively) at the highest wind speed. Adding rice straw reduced sediment loss to 3573 g m-2 at the highest wind speed, but the effect was not significant due to mobilization of the mulch. Tackifiers reduced sediment loss for bare soil at moderate and high wind speeds, and for mulch treatments at high wind speed. These results may aid management decisions when reducing aeolian sediment transport after wildfires.