The rate of weight loss is one of the most commonly cited parameters in litter decomposition studies. In spite of recent advances in the direct measurement of respiration rates, litter bags, litter standing crop measurements, and decomposition standards continue to be recommended as the most reliable methods for determining absolute decomposition rates (Anderson & Ingram 1989). All three of these methods are frequently complicated by soil contamination. Three options are currently available to deal with this problem: (1) exclusion in the field with physical barriers, (2) mechanical separation in the laboratory, or (3) calculation based on the measurement of a constituent of the organic material, or of the soil. Soil can be at least partially excluded in the field by reducing the mesh size of litter bags. However, reducing mesh size may exacerbate other widely-recognized limitations of litter bags by excluding macroinvertebrates (Holter 1979), or by affecting microorganism populations through microclimate modification (St. John 1980).