Surface residue effects on erosion of thawing soils

Soils that experience freezing and thawing are most susceptible to erosion during the late winter and early spring. Greater than 50% of the total annual erosion may occur during this period in parts of the USA and Canada. In this period the upper layer of the soil profile thaws due to rising temperatures, while the subsurface layer stays frozen, greatly limiting water movement through the soil profile, weakening the surface soil, This experiment was conducted to evaluate the effects of four treatments - residue cover (0, 10, 30, and 80%), soil inclination (5, 9, and 13%), soil type (loess and glacial till), and a frozen vs. non-frozen subsurface layer - on two response parameters (soil eroded and soil splash) from small laboratory plots. An erosion box with a surface area of 0.13 m(2) received 0.0343 m of simulated rainfall in a 30-min period. Significantly higher erosion (0.212 vs. 0.152 kg) and soil splash (0.090 vs. 0.066 kg) was observed for the frozen than for the unfrozen subsurface soil layer treatments, respectively. The most erodible condition (13% inclination with frozen subsurface layer) was the most responsive to surface residue cover, 0.335 vs. 0.111 kg eroded soil for 0 vs, 80% residue cover, respectively. The least erodible condition (5% inclination without a frozen subsurface layer) was the least responsive to residue cover (0.161 vs. 0.076 kg eroded soil for 0 vs. 80% residue cover). Residue cover seems very important for reducing soil loss during the soil thawing period, particularly on steep slopes, and may be more important for subsurface frozen conditions than when subsurface frozen layers do not exist.