Tillage effects on soil physical properties of a Typic Kanhapludult and growth and development of loblolly pine (Pinus taeda L.) (South Carolina).

摘要

Soil physical properties of a Typic Kanhapludult in the South Carolina Piedmont were evaluated three years following disking and ripping. Neither treatment had a significant effect on soil bulk density (Db) or total porosity (F) within the volume of soil hypothetically impacted (surface soil for disking and subsoil for ripping). Slight reductions in Db and increases in F within surface soil adjacent to the planted row associated with disking did not extend beyond 30 cm from planted row. Disking increased Db and microporosity at depths below 20 cm and significantly reduced mechanical impedance (MI) in the surface 0 to 10 cm. Ripping increased mesoporosity in soil immediately surrounding the rip at all depths except surface. However, ripping had no significant effect on F at any depth in the planted row, primarily due to concomitant reductions in microporosity. Ripping significantly reduced MI at all depths in planted row. At 100 cm from planted row, ripping resulted in higher MI in the surface 30 cm of soil.; Tillage had no significant effect on survival of planted loblolly pine. Ripping significantly increased two-year height, while disking had no significant effect. Height growth response averaged 0.1 m for both tillage treatments after the third and fourth growing seasons. Ripping resulted in an over 100% increase in root density relative to control plots. Disking had no significant effect on root density, although disked plots averaged 40% more roots than controls.; Field determinations of Db using two hammer-driven samplers (Ruark and Uhland) were compared. Sampling method accounted for only 5% of variability in Db, while depth was responsible for 43%. Method, depth, and method x depth interaction had no significant effects on either the mean or standard deviation of Db. However, Db was significantly greater for Uhland than Ruark sampler below a depth of 15 cm. The Ruark sampler required approximately 42% less time than Uhland, due mainly to differences in field sampling procedures.