Diversity, abundance and function of soil invertebrate fauna in relation to quality of organic residues

Abstract

This thesis is a study of the role of soil invertebrate fauna in decomposition of organic residues and thus nutrient release, soil structure and soil-water relations is well recognized, the scope for their manipulation to derive the potential benefits is little understood. A study was undertaken to test the hypothesis that the diversity, abundance and function of soil fauna are related to quality of organic residues used. The study was conducted during the 1997 short rains (Octo.1997 - Feb. 1998) on a farm in Western Kenya with the following treatments: (1) control without any input, (2) fertilizer at 120 kg N, 150 kg P and 100 kg K ha-1 (3) tutgibua (Tithonia diversifolia [Hermsely] A. Grey) biomass and (4) condition at 5 t ha-1 dry weight. The treatments were replicated four times in a randomized block design. Macro and meso-fauna diversity and abundance were monitored in soil monoliths (25 x 25 x 30 cm) and soil cores (10 cm diameter and 30 cm depth), respectively, at the beginning of the season, six weeks after sowing maize and at maize harvest.