Initial contents of residue quality parameters predict effects of larger soil fauna on decomposition of contrasting quality residues

A 52-week decomposition study employing the soil larger fauna exclusion technique through litter bags of two mesh sizes (20 and 0.135 mm) was conducted in a long-term (18 yr) field experiment. Organic residues of contrasting quality of N, lignin (L), polyphenols (PP) and cellulose (CL) all in grams per kilogram: rice straw (RS: 4.5N, 22.2L, 3.9PP, 449CL), groundnut stover (GN: 21.2N, 71.4L, 8.1PP, 361CL), dipterocarp leaf litter (DP: 5.1N, 303L, 68.9PP, 271CL) and tamarind leaf litter (TM: 11.6N, 190L, 27.7PP, 212CL) were applied to soil annually to assess and predict soil larger fauna effects (LFE) on decomposition based on the initial contents of the residue chemical constituents. Mass losses in all residues were not different under soil fauna inclusion and exclusion treatments during the early stage (up to week 4 after residue incorporation) but became significantly higher under the inclusion than the exclusion treatments during the later stage (week 8 onwards). LFE were highest (2-51%) under the resistant DP at most decomposition stages. During the early stage (weeks 1-4), both the initial contents of labile (N and CL) and recalcitrant C, and recalcitrant C interaction with labile constituents of residues showed significant correlations (r = 0.64-0.90) with LFE. In the middle stage (week 16), LFE under resistant DP and TM had significant positive correlations with L, L + PP and L/CL. They were also affected by these quality parameters as shown by the multiple regression analysis. In the later stages (weeks 26-52), the L/CL ratio was the most prominent quality parameter affecting LFE.