Over the 6 year period, there were no significant differences in relative contents of textural
separates of sand, silt and clay for the surface 0-5 and 5-10 cm layers. The gravel concentration
of the surface 0-5 and 5-10 cm layers, however, increased significantly due to plowing and
mixing of the surface and subsoil layers. Soil bulk density of 0-5 and 5-I0cm layers,
respectively, increased in all treatments from initial values of 1.02 and 1.16gcm 3 in 1982 to
1.43 and 1.65 g cm -3 at the end of cropping cycle in 1986.