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 annu al 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 tempera tures, while the subsurface layer stays frozen, greatly limiting water move ment 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 respon se 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 simulate d rainfall in a 30-min period. Significantly higher erosion (0.212 vs. 0.15 2 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 m ost 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% in clination without a frozen subsurface layer) was the least responsive to re sidue cover (0.161 vs. 0.076 kg eroded soil for 0 vs. 80% residue cover). R esidue cover seems very important for reducing soil loss during the soil th awing period, particularly on steep slopes, and may be more important for s ubsurface frozen conditions than when subsurface frozen layers do not exist .