PROBLEMS AND PROSPECTS OF FERTILISER USE IN PLANTATION FORESTRY IN THE TROPICS

Regular use of forest lands by man, poor forest management and harvesting of forest products leads to loss of soil nutrients and decreased soil fertility. Organic and mostly inorganic fertiliser uses in forestry to correct these nutrient losses pose many environmental problems. This paper attempts to highlight the problems inherent in fertiliser use in forest plantations as well as prospects for mitigating the problems. Generally, fertiliser use increases and maintains productivity in forest plantations; prolonged fertiliser use however produces some unpalatable non-target effects such as: boosting or decreasing the populations of decomposer organisms (micro-flora and micro-fauna); production of nitrous oxide, methane, ammonia and carbon dioxide gases which are greenhouse gases implicated in global warming; pollution of drinking water; promotion of nutrient antagonism. Nutrient requirement in forests can be minimised through good forest management practices such as; debarking the tress in situ at the forest site to reduce nutrients removed during tree harvest; biological nitrogen fixation by planting leguminous trees or shrubs in plantations; breeding plant components that influence uptake of nutrients by trees. Waste materials can be incorporated or blended with inorganic fertiliser to reduce the high cost and adverse effects of inorganic forest fertilisation.