Earthworm influence on N availability and the growth of Cecropia schreberiana in tropical pasture and forest soils

This greenhouse study examines the effects of Pontoscolex corethrurus on th e growth of Cecropia scheberiana in forest and pasture soils. Four treatmen ts (0, 2, 20 worms and 0 worms + urea fertilizer) were applied to the soils to test if earthworms affect nitrogen availability, and consequently the g rowth of C. scheberiana, We recorded the number of seedlings, leaves, and h eight of plants, and measured NH4+ and NO3- concentrations in water leachat es during a six month period. The growth of C. scheberiana and nitrogen con centration in leachates differed between pasture and forest soils. addition of 20 worms per pot doubled nitrate and ammonium concentrations in leachat es as compared with the controls. However, earthworms did not affect the ge rmination of C. scheberiana in both pasture and forest soils. Although eart hworms did enhance nitrogen availability and mineralization,we conclude tha t nitrogen is not a limiting factor for Cecropia growth in either pasture a nd forest soils.