Field Wind Tunnel Testing of Two Silt Loam Soils On the North American Central High Plains.

The change from conventional tillage to no-till cropping systems and the emergence of cropping systems with fewer and shorter fallow periods has resulted in reduced wind erosion on the North American Central High Plains.  This reduction has been attributed primarily to increased surface coverage by crop residues, but changes to soil physical and chemical properties resulting from management changes may also play a role.  We tested the intrinsic erodibilities, the erodibility and dust emission potentials of soils without surface residue, of soils under long term studies of tillage management and crop rotations at locations near Tribune, KS and Akron, CO.  The studies at both sites had been in existence for greater than 15 years.  The surfaces were cleared of crop residue, tilled, raked, and rolled, resulting in uniform, smooth surfaces with minimal surface roughness.  A 6 m long wind tunnel was placed on the prepared surface and tests at each plot used a 12 ms^-1 wind speed and consisted of an initial 5 minute test without introduced silica abrader followed by a 30 minute test and a subsequent 10 minute test, both conducted with introduced silica abrader.  Dust emissions were measured using an isokinetic vertically integrating slot sampler that aspirated suspended load through glass fiber filters changed at the end of each of the tests detailed above and through an optical dust analyzer that provided a continuous record.  No significant differences were noted among tillage systems or crop rotations for dust emissivity. However, the results indicated that no-till systems and reduced till systems are somewhat more dust emissive than conventionally tilled systems.  This finding is in agreement with previous findings from studies of dust emissions potentials conducted in a laboratory cone abrader.