Effects of Mechanical Site Preparation on Growth of Oaks Planted on Former Agricultural Fields

Mechanical site preparation is frequently proposed to alleviate problematic soil conditions when afforesting retired agricultural fields. Without management of soil problems, any seedlings planted in these areas may exhibit poor growth and survival. While mechanical site preparation methods currently employed in hardwood afforestation are proven, there is a substantial void in research comparing subsoiling, bedding, and combination plowing treatments. A total of 4,320 bare-root Nuttall oak (Quercus texana Buckley), Shumard oak (Quercus shumardii Buckley), and swamp chestnut oak (Quercus michauxii Nutt.) seedlings were planted in February 2008 on three Mississippi sites. All sites were of comparable soils and received above average precipitation throughout the three-year duration of the study. Four site preparation treatments were replicated at each site, with 480 seedlings planted in each of nine replications, and a total of 1,440 seedlings per species planted across all sites. Mechanical treatments were installed using 3.1 m row centers, with treatments as follows: control, subsoiling, bedding, and combination plowing. Treatment effects on seedling height, groundline diameter (GLD), and survival were analyzed. Seedlings exhibited greater height in bedded and combination plowed areas (79.7 cm to 102.7 cm and 82.6 cm to 100.1 cm, respectively) compared to subsoiled or control areas (70.4 cm to 84.6 cm and 71.4 cm to 86.9 cm, respectively). Greater GLD was observed in bedded and combination plowed areas (11.9 mm to 18.4 mm and 12.2 mm to OPEN ACCESS