The impact of the addition of Eucalyptus grandis wood chips on nitrogen availability in plantation soils: scientific paper

Abstract

The impact of plantation residues, as a result of clearfelling, on nutrient availability in plantation systems, as well as the difficulties during subsequent planting and harvesting, should be considered in the development of plantation management strategies. The aim of this experiment was to determine if the addition of stump wood chips would result in the immobilisation of nitrogen. Soil from two plantations, one of the Kranskop soil form (0,57% nitrogen) and one of the Hutton soil form (0,23% nitrogen), were analysed in a laboratory experiment for changes in nitrogen availability. Soils were amended with wood chips and varying amounts of nitrogen fertilizer. Inorganic nitrogen was measured after 14,60 and 90 days of aerobic incubation. Net mineralisation rates, regardless of treatment or soil, ranged between -24,98 and +2,53 mg nitrogen / g soil / day, over the 3-month incubation period. Immobilisation of nitrogen was found to occur in those treatments that received the highest nitrogen additions. Addition of wood chips on their own did not alter the nitrogen availability patterns. However, it was observed that wood chips, together with high levels of additional nitrogen, resulted in an extended period of release of nitrogen in these plantation soils.


Southern African Forestry Journal No.196, 2003: 9-14