Tillage Effects on Bulk Density and Soil Strength of Two Mollisols
1985
Hill, R. L. | Cruse, R. M.
Farmers in the Midwest are concerned that continuous no-tillage cultivation may be causing soil compaction within their fields. A study was conducted to determine the effects of conservation and conventional tillage on soil bulk density and soil strength of two Mollisols. Two locations, each having randomized complete-block designs with three replications of continuous corn plots under no-tillage, reduced tillage, and conventional tillage were used. One location, site 1, was in its 2nd yr of tillage experimentation and the other location, site 2, was in its 8th yr of tillage experimentation. Gamma irradiation was used to determine bulk densities of undisturbed soil cores. Soil strength was determined by using a fall cone penetrometer at soil water matric potentials of 0, −20, and −40 kPa. Tillage treatments did not have a statistically significant effect on bulk density at either site. Bulk density increased significantly with depth for the three tillage treatments at both sites. Tillage treatments had significant effects on soil strength at site 2, but not at site 1. Strength of soil at site 2 under reduced tillage was not significantly different than for soils under no-tillage, but the soils under both these tillage systems had significantly greater soil strengths than that observed for conventionally tilled soil. The pattern of differences in soil strength due to tillage treatment was the same at site 1, but the differences were not statistically significant. Soil strength increased with decreased matric potential for the three tillage treatments of both sites. Neither bulk density nor soil strength of the soils under any of the tillage systems for the 0 to −40 kPa matric potential range appeared to be large enough to have an appreciable inhibitory effect on plant root growth.
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