Decomposition of red clover ( Trifolium pratense) roots

We have followed the decomposition of red clover root remains and described the process. In this investigation, red clover roots, divided into three diameter classes: < 1 mm, 1–4 mm and > 4 mm, were incubated in mesh bags in a loam soil at a temperature of 22°C and a moisture of pF 2–3 for up to 196 days. Analyses were made on the initial dead plant material and on mesh-bag contents of the 1–4 mm roots for the amounts of water and ethanol solubles, solid polysaccharides, lignin, ash, carbon, nitrogen and fungal mycelium. Organic matter mass loss was fast during the first 13 days (44%) and almost ceased after 30 days when about 29% of the organic material remained. There was no notable difference in mass- or nitrogen loss from roots of different diameters. The carbon-to-nitrogen ratio of the root remains decreased from initially 25–27 to 11–13 at the end of the incubation. The high rate of mass loss at the beginning is explained by the considerable initial concentration of water-soluble substances (31%), being the fraction which decreased the fastest (roots 1–4 mm φ). Glucans comprising 40% of the initial root material, were degraded linearly to total mass loss. Other polysaccharides (galactans, mannans, xylans, arabans and rhamnans) disappeared more slowly than the glucans. The amount of total fungal mycelium within the decomposing root remains increased during the incubation from 55 to 867m g −1 of organic material.