On-Farm Assessment of Crop Residue Removal Impacts On Soil Wind Erodibility Parameters in the Centeral Great Plains.

Excessive crop residue removal for livestock and biofuel production may accelerate soil erosion by wind, particularly in semiarid regions such as the central Great Plains. We conducted an on-farm study to determine the impacts of crop residue removal on soil physical properties affecting wind erosion such as erodible fraction (EF <0.84 mm aggregates), geometric mean diameter (GMD) of dry aggregates, dry aggregate stability, and soil surface roughness. Five crop residue removal treatments (0, 25, 50, 75, and 100% removal) with four replications were established after wheat harvest in 9 m by 9 m plots across six farmer’s no-till fields in western Kansas in summer 2011. Wheat stubble was cut with a forage harvester at different heights corresponding to the five treatments. Soil samples from the 0- to 5-cm depth were taken in fall 2011 (four months after removal) and spring 2012 (eight months after removal). A rotary sieve was used to obtain seven soil aggregate size fractions (<0.42, 0.42-0.84, 0.84-2, 2-6.35, 6.35-19.05, 19.05-44.45, and >44.45mm) for computing the EF and GMD. Dry aggregate stability was determined by the crushing test. Pin meter was used to determine the soil surface roughness and pictures were analyzed using SigmaScan Pro 5.

Results showed a general trend of increase in EF with an increase in crop residue removal rates. Four months after residue removal, the EF increased between 5 and 10% after 100% residue removal rate in four of the six sites. Eight months after residue removal, the EF increased between 7 and 37% after 100% residue removal rate in all six sites. Also, residue removal generally reduced GMD of dry aggregates and soil surface random roughness. Dry aggregate stability also decreased by about 15 to 27% with 100% of removal at four sites in spring 2012. Overall, results suggest that excessive (> 75%) crop residue removal can rapidly increase soil’s susceptibility to wind erosion in some soils. Differences in length of previous no-till management and amount of residue produced among fields appeared to affect crop residue removal impacts on soil wind erodibility.