EFFECTS OF WATER HYACINTH (Eichhornia crassipes) COMPOST ON SOIL PROPERTIES AND MAIZE (Zea mays L.) GROWTH AND YIELD IN LAKE VICTORIA BASIN, KENYA

Abstract

The decline in organic matter content and fertility of soils in sub-Sahara Africa often contribute to losses in agricultural production. Organic amendments could be a useful tool to improve soil fertility. The objectives of this study were to assess the quality of water hyacinth (Eichhornia crassipes) compost prepared by three composting systems (experiment one)  and their effects on soil fertility and plant yield (experiment two) determined between November 2019 and August 2020 in Lake Victoria basin. The composting systems consisted of thermophilic composting as control treatment, vermicomposting and composting using effective microorganisms (EM) solution) replicated three times. The second experiment was conducted in a randomized complete block design (RCBD) with five fertilizer treatments (vermicompost, thermophilic compost, EM compost, positive control (inorganic fertilizer) and negative control (no fertilizer)) replicated three times. The composting systems significantly affected water hyacinth compost maturity period and its quality parameters. EM composting technology hastened compost maturity and increased the pH (8.5), electrical conductivity (3.24), micronutrients concentration (iron, copper, zinc and manganese) and fungal abundance (5.63 x 10⁴ CFU/g sample) of the end product. The highest mean water holding capacity (220 % by wt.), total nitrogen content (2.72 %), total phosphorus content (1.29 %), total potassium content (1.71 %) and bacterial abundance (3.84 x 10⁷ CFU/g sample) was recorded under vermicomposting technology. Fertilizer treatments also significantly affected the selected soil properties, maize growth and yield parameters. Plots treated with vermicompost treatment recorded the highest pH (>0.5 units). Crop emergence above the threshold level (88%) was observed in plots treated with organic amendments and no fertilizer treatment. Higher plant height (239.4 cm), nitrogen uptake (130.8 kg ha^-1) and grain yield (5580 kg ha^-1) were recorded under vermicompost treatment. This suggests that vermicompost could be a promising substrate for amending acidic soils and improving crop productivity.