First-year survival and height-growth of red ceiba following various site preparation techniques on vertic soils in northern Colombia

If growth of red ceiba, Bombacopsis Quinata (Jacq.) Dugand, is to be increased in plantations established on Vertisols, site preparation techniques must be identified to overcome the soil management difficulties of these soils. This research was conducted to identify specific site preparation techniques appropriate for Vertisols that increase survival and height growth of red ceiba. The effects of subsoiling within the row (prior to planting) to depths of 40 and 60 cm, subsoiling between the rows, and additions of organic mill waste on red ceiba survival and height growth, soil water content, bulk density, and penetrometer resistance were investigated. The soil was a very fine, montmorillonitic, isohyper-thermic Entic Chromustert. No difference in survival due to subsoiling was found, but the additions of mill waste significantly decreased survival after 1 year (94.7%) compared to the control subplot (98.7%). Height was increased by subsoiling to the 40-cm depth (92.3 cm) and to the 60-cm depth (97.4 cm) over no subsoiling (80.7 cm). Trees on the subplots receiving mill waste were significantly lower in height (83 cm) compared to the control subplots (93.1 cm) and the subsoiling between the planting rows subplots (94.2 cm). Survival was most highly correlated with bulk density at the 50-cm depth within the planting row (r=–0.44) and height with soil water content at the 30-cm depth within the planting row (r=–0.56). Subsoiling affected height more than survival. Subsoiling to 40 cm is the most cost-effective treatment. Mill waste addition did not improve height or survival, possibly due to harmful decomposition by-products.