02003nas a2200157   4500008004100000245005400041210005400095300001300149490000700162520154000169653000901709653001201718100001701730700001901747856007901766       1984                        eng d00aSoil structure as influenced by simulated tillage0 aSoil structure as influenced by simulated tillage  a879 -8840 v483 a<p>Soil is often intensively manipulated by tillage, equipment traffic, and preparation for laboratory analysis. Realizing that manipulated and reconstituted soils have been and are being used in soil structure research, we used surface-soil samples of cultivated and noncultivated Reading silt loam (fine, mixed, mesic, Typic Argindolls) to evaluate the effects of simulated tillage on soil structure and to determine how well the structures of disturbed soils represent the structures of nondisturbed soils of similar composition. Soil cores 86 by 60 mm were formed after the following treatments had been applied: ultrasonically dispersed and freeze- dried, crushed and passed through a 2 mm sieve, and nondisturbed. The soil structural differences were evaluated by soil-water-characteristic curves, saturated-hydraulic conductivities, compression indices, bulk densities, wet and dry aggregate stabilities, and scanning-electron-microscopy. The results show that the soil structures of reconstituted, intensively or even mildly manipulated soils differ considerably from the nondisturbed soils of the same makeup. The greater the disturbance, the greater the differences between the nondisturbed and disturbed soils. The main differences were caused by the destruction of cements and bridges between individual aggregates, which create large, compound-unit (ped) structures. Additional Index Words: dry-aggregate stability, wet-aggregate stability, compression indices, soil-water characteristic, scanning- electron microscopy</p>10asoil10atillage1 aPowers, D.H.1 aSkidmore, E.L.  uhttp://knz.lternet.edu/content/soil-structure-influenced-simulated-tillage