Effects of varying weeds substrates on vermicomposting and germination, nodulation and vegetative yield response of cowpea (Vigna unguiculata M. Walp) to the compost

Abstract

Suitability of some grasses, weeds and poultry droppings, either sole or in combination for vermicomposting as well as the effect of vermicompost on soil properties, growth and nodulation of cowpea were assessed. The results indicated that poultry droppings, sole grass or weed substrates were not suitable for vermicomposting. However, suitable substrates were obtained when grasses and weeds were combined. Vermicomposts were 97-89% higher in available P content than the unamended soil, and the soils amended with vermicompost were 5 - 10 times higher in available P (16.23 – 31.89ug g-1) than the unamended soil. The vermicomposts were significantly different (p < 0.05) in available P content before and when mixed with soil. Amending soils with vermicompost from weed and grass combination significantly (p < 0.05) increased soil moisture content at field capacity, CEC, exchangeable Ca, K and available P as well as nodule number, dry weight per plant of cowpea. There is an indication that sole grass or weed substrates could contain compounds that are toxic to worms suggesting that quality indicators have to be established for vermicomposting. 

Keywords: Vermicompost; Eudrilus eugeniae; Weeds; Grasses; Cowpea