Temporal Effects of Subsoil Compaction on Soil Strength and Plant Growth

Abstract

AbstractIn recent years, scientists have become concerned that heavy farm equipment is causing soil compaction below the nominal depth of tillage. Compaction this deep may not be ameliorated after one season's freeze‐thaw and wet‐dry cycles. Experiments were conducted on a Kewaunee (fine, mixed, mesic Typic Hapludalf) and Rozetta (fine‐silty, mixed, mesic Typic Hapludalf) soil to determine the duration and effect of subsoil compaction on soil strength and corn (Zea mays L.) growth. Soil at two sites was compacted with 8 and 12.5 Mg axle loads in the spring of 1983. Cone‐penetration resistance of compacted soil was significantly higher than that of uncompacted soil below the plow zone. Plant heights, at physiological maturity averaged across both sites, were reduced 13 and 26% on the 8‐ and 12.5‐Mg compaction treatments, respectively, compared with the control in 1983. In 1984, average mature plant heights were 2.4, 2.3, and 2.3 m for the control, 8‐, and 12.5‐Mg compaction, respectively. Three years after the compaction was applied (1986), the average mature plant height for the 8‐ and 12.5‐Mg compacted sites were reduced 3.1 and 4.3% compared with the control. Nitrogen and K uptake was reduced by compaction. Iron, Al, and Mn uptake increased with increasing levels of compaction on the Kewaunee soil in 1983. In 1983, yields for the 8‐ and 12.5‐Mg treatments on the Rozetta soil were reduced 4 and 14%, respectively, relative to the control. Similarly, yields for the Kewaunee soil were reduced 14 and 43%. Yields for the Kewaunee soil were not reduced by compaction in 1984, although 5 and 9% reductions were observed at the Rozetta site. Yields were not affected the following 2 yr (1985 and 1986), whereas the resistance to cone penetration was significantly higher in the compacted plots compared with the control.