Effect of cattle manure and biodigester effluent levels on growth and composition of water spinach

Abstract

An experiment was conducted at the Livestock Research Center, Laos from 16th of September to 14th of October, 2005. The objective was to evaluate the effect of different levels of effluent from a biodigester charged with pig manure and the interaction with low and high cattle manure level mixed with the soil. A randomized complete block design with two factors was used. The factors were: cattle manure at levels of 20 and 100 tones/ha and biodigester effluent at levels of 0, 10, 20, 30 and 40 kg/ha. There were 3 replications of each treatment arranged within 3 blocks. In a 28 day growth period, yield of fresh leaves, stems and entire plant biomass of water spinach was increased by 109, 155 and 137% for the 100 compared with 20 tonnes/ha cow manure application. Comparable figures for DM yields were: 100, 135 and 114%. There were linear responses in biomass yield to increasing levels of biodigester effluent. In terms of response to added N this was about 1.25 kg DM per 1 kg additional N from cow manure, compared with an additional 7.5 kg DM biomass per 1 kg added N from biodgester effluent.