Rm. Atiyeh et al., Changes in biochemical properties of cow manure during processing by earthworms (Eisenia andrei, Bouche) and the effects on seedling growth, PEDOBIOLOG, 44(6), 2000, pp. 709-724
The biochemical changes in fresh cow manure caused by the earthworm Eisenia
andrei (Bouche) were measured over a period of four months, under controll
ed laboratory conditions. Earthworms were introduced into each of four plas
tic containers (0.4 x 0.27 x 0.15 m) containing fresh cow manure (2500 g),
and four containers containing manure but without earthworms served as cont
rols. Earthworms reduced the pH and decreased the moisture content in the m
anure. The C:N ratio of the manure with or without earthworms decreased pro
gressively from 36 to 21. The ash and total nitrogen contents increased gre
atly for a few weeks after the introduction of earthworms, reflecting a rap
id breakdown of carbon compounds and mineralization of nitrogen by the eart
hworms. CO2 evolution decreased rapidly (44 %) one week after the introduct
ion of earthworms, and continued at a lower rate throughout the 17 weeks (5
1 % reduction as compared to 22 % without earthworms), indicating increasin
g stability of the organic matter. Earthworms reduced microbial biomass ear
ly in the process, but enhanced nitrogen mineralization and increased the r
ates of conversion of ammonium-nitrogen into nitrate. The major general eff
ect of earthworms on the organic wastes was to accelerate the maturation of
the organic wastes as demonstrated by enhanced growth of lettuce and tomat
o seedlings.