Effect of Lime Application to Acidic Soils on Oleoresin Yield Tapped from Pine Plantations in South China

Abstract

Oleoresin is a major non-forest product collected from commercially mature or near mature pine trees. Efforts have been made to increase oleoresin yield, but basically limited to the genetic im-provement of planting materials and the application of chemical stimulants to tapping surface of trees. Nutrition management may play a role, particularly for pine stands suffering from soil acidi-fication and degradation. We set up a field experiment including application of water retainer, NPK complex fertilizer, lime and borax in different combinations to pine stands for oleoresin tap-ping with extremely low soil pH value and nutrition. Lime significantly affected the annual yield of oleoresin tapped from two pine species studied (P < 0.05). Among 3 levels of lime applied (0, 100, 200 g/tree), the oleoresin yield increased as the dose increased in slash pine, but was highest at 100 g/tree in masson pine. The doses of 167 g and 133 g of lime per tree were optimal or close to be optimal for slash pine and masson pine, respectively. The effects of other three matters applied were statistically insignificant (P > 0.10). In addition, all of the four matters applied did not influ-ence the growth of both pine species. We concluded that proper use of lime alone may generate 15% to 35% of gain in oleoresin production for pine plantations with similar soil conditions in the re-gion. We also discussed the potential of comprehensive soil or site management, and proposed further research for improvement of pine oleoresin production.