Soil Loss, Runoff, and Water Quality of Seeded and Unseeded Steep Watersheds following Prescribed Burning

Abstract

Seeding [with mixed grasses] of steep slopes (37-61%) after burning [to improve forage quality] on the Edwards Plateau in central Texas [USA] reduced soil losses 78-93%. The major impact of burning on soil losses was significantly reduced in 3 mo. on burned and seeded watersheds, but not for 15-18 mo. on unseeded watersheds. Stability (soil losses comparable to pretreatment levels) was reached in 6 mo. on burned and seeded watersheds. Soil loss rates stabilized when cover (live vegetation plus litter) reached 64-72% during normal to wet years or 53-60% during dry years. Thus, amount of precipitation and cover are closely tied to soil losses. Overland flow stabilized in 4-5 yr on unseeded watershed and in 1-2 yr on seeded watersheds. Water quality, lowered slightly by burning, returned to preburn levels within 2 yr after seeding. Without seeding it took 4 yr to reach preburn levels. Overall, water quality change following burning was not considered to be serious.