Influence of soil characteristics on teak (Tectona grandis L. f.) establishment and early growth in tropical Northern Australia

The establishment and early growth of a clonal teak plantation on a leached and acidic alluvial soil on North Queensland, Australia was studied over 18 months. The soil was treated with three lime treatments (0, 1 and 2 Mg ha−1) and three CaCl2 treatments (0, 50 and 100 kg ha−1). After 18 months, the average tree height ranged from 105 to 227 cm and survival ranged from 39% to 97%. Tree height and survival was not causally affected by the lime or CaCl2 treatments. Detailed investigation of soil properties in each plot revealed teak growth and survival was positively affected by total soil carbon concentration, water-holding capacity (WHC) and Al saturation, and negatively affected by exchangeable Mg and DTPA-extractable Mn. Results indicate that teak is relatively tolerant of low pH (pH 4.4) and moderately high exchangeable Al concentrations (1 cmol(c) kg−1) in soil. We conclude that organic matter (carbon) plays a critical role at our site by improving the soil physical characteristics such as soil porosity, aggregate stability and WHC. Also, sites with high total carbon had high Al saturation of the soil and high teak growth, suggesting that soil C acts by immobilising Al and Al impairs soil C degradation. Growth may be impaired by Mn toxicity and by Mg affects on soil structure. From a teak plantation management perspective, it is desirable to select soils with high organic matter, whereas pH and Ca status have little effect on early growth