Soil Texture, Organic Matter and Nutrients Affect Production of Acacia in Northeast Vietnam

Soil provides nutrients, water, and growing space for plants, and thus is the basis for life on earth. Soil nutrient availability impacts productivity of terrestrial ecosystems i.e. forest. However, support for this phenomenon in the tropics remains elusive. In this study, the effects of soil properties including texture, organic matter and nutrients on production of Acacia hybrid and A. mangium plantations in Northeast Vietnam were studied. Thirtythree sample plots of 500 m2 (20 m × 25 m) each were established in plantations of 1–14 years old for measuring stem diameter at breast height and height for all Acacia trees. In each plot, a 0–30 cm depth soil sample was taken for analyzing soil texture, organic matter, and nutrients. While allometry was used to estimate standing volume (production) of all measured stems. The results indicated that both species had rapid growth until 8th year after planting, then growth speed decreases as age increasing. The ratio of loam particles in soil controls production of both species, as higher loam ratios lead to lower production in terms of the standing volume. While higher phosphorous availability in the soil will lead to higher production of A. mangium but not A. hybrid. There weren’t any relationships between production and soil nitrogen and potassium for both species. It is concluded that A. hybrid and A. mangium should be logged at the age earlier than 8 years old for pulpwood to maximize production, rapid reinvestment, and benefit return. Fertilizing phosphorus to acacia plantations should be conducted to increase production, while potassium and nitrogen should not be applied.