Soil Wind Erosion Hazard of Spring Wheat-Fallow as Affected by Long-Term Climate and Tillage

We hypothesized that drought accelerates wind erosion by increasing plant and soil factors of erodibility together, compounding the erosion hazard. Erodibility factors measured in biennial spring wheat-fallow on Pachic and Typic Haploborolls soil were (i) soil-inherent wind erodibility (SIWE) by rotary sieving, (ii) surface roughness by pin meter and chain methods, (iii) standing residue profile, and (iv) residue coverage photographically. Four tillage treatments ranged from low residue (LR) to no-till (NT). The erodible fraction of surface soil (a SIWE measure) changed from 53% during a dry period (1989-1990) to a less erodible 26% during a wet period (1992-1994). Median erosion protection values calculated from flat and standing residue measurements made after seeding were, respectively, 16 and 43% in 1989 to 1990, and 80 and 76% in 1992 to 1994. Soil losses estimated by RWEQ model equations were 11 to 6100 times greater during 1989 to 1990, compared with 1992 to 1994. No-till was protective, and estimated soil losses on LR were up to 3000 times greater than those on NT, However, low residue yields in 1988 (930 vs. 3640 kg/ha avg.) resulted in inadequate protection after seeding in 1990, even in NT; and soil losses in LR and NT were 13 and 8 Mg/ha, respectively. Results indicate biennial small grain-fallow is nonsustainable in the long term from a soil-erosion perspective.