Nutrient losses from litterbags containing Pinus radiata litter: influences of thinning, clearfelling and urea fertiliser

Abstract

A 4-year study using nylon mesh bags in a Pinus radiata D. Don stand showed that tree canopy density had little or no effect on litter decomposition rate or loss of nutrients. The application of urea at 200 kg N/ha raised the nitrogen concentration in the litter by 0.5%; even though this higher margin was consistently maintained throughout the study, decomposition rate and nutrient release were unaffected. During the study relative rates of loss of dry weight and nutrients from litterbags were nitrogen < manganese = calcium = zinc = magnesium < dry weight < phosphorus < boron < potassium. There was little or no loss of nitrogen during the first 97 weeks; this was followed by a small release. In sharp contrast there were substantial losses of phosphorus and potassium within 9 weeks, and potassium continued to be lost until 90% had been released after about a year.