Soil Characteristics and Wind Erosion Potential of Wheat-Oilseed-Fallow Cropping Systems

Oilseeds are integral to the production of biofuels and diversifying rainfed cropping systems in the US Pacific Northwest (PNW). However, there is evidence to suggest greater potential for wind erosion when growing oilseeds in wheat (Triticum aestivum L.) rotations. Little is known concerning the impact of growing oilseeds on the soil surface characteristics that affect erosion. Soil characteristics were examined during the fallow phase of three crop rotations: (i) winter wheat-summer fallow (WW-SF), (ii) winter wheat-camelina (Camelina sativa L. Grantz)-summer fallow (WW-C-SF), and (iii) winter wheat-safflower (Carthamus tinctorius L.)-summer fallow (WW-S-SF) at Lind and Ritzville, WA. Crop residue biomass and soil water content, roughness, surface strength, and aggregate size distribution were measured immediately after sowing winter wheat. Camelina and safflower did not affect soil water content, random roughness, penetration resistance, geometric mean diameter, or the erodible fraction, possibly due to the short duration over which the rotations were monitored in this study. Flat residue biomass and cover, however, tended to be greater in the WW-SF rotation. The Revised Wind Erosion Equation suggested that sediment transport could be from 57 to 212% greater for the WW-C-SF or WW-S-SF than the WW-SF rotation due to differences in crop residue characteristics after sowing wheat. These results indicate that crop residue must be carefully managed to minimize the occurrence and intensity of wind erosion from dryland oil-seed cropping systems in the PNW. Specifically, no-till management may be required to manage crop residues during the fallow phase of a wheat-oil-seed-fallow rotation to control wind erosion.