Influence of Brewery Waste and Animal Manure-Based Compost on the Growth of Green Amaranth in Sandy Tropical Soils

The productivity of sandy tropical soils may be enhanced through the application of composted organic materials.This study investigates the effects of composted mixtures of brewery spent grain (BSG) and animal manures on the growth of green amaranth (Amaranthus caudatus L) under field conditions.Composted treatments included BSG mixed with poultry droppings (PD) or cattle dung (CD) in volumetric ratios of 1:1 and 2:1 prior to composting, resulting in four compost variants: BSG+PD(1:1), BSG+PD(2:1), BSG+CD(1:1), and BSG+CD(2:1).Additionally, composted BSG alone served as a reference.Each amendment was added at 20 t ha -1 , alongside an un-amended control for comparative purposes.Growth and yield assessments conducted four weeks post-sowing revealed that not all amended treatments outperformed the control.Notably, the BSG+PD(1:1) treatment consistently increased total biomass (fresh and dry matter yields by approximately 143% and 58%, respectively) as immediate effects, and significantly more (184% and 108%, respectively) as residual effects when compared to the control.Leaf yields under this treatment showed increases of 173-177% (immediate effects) and 122-125% (residual effects).These variations in amaranth growth and yield were primarily attributed to improvements in soil exchangeable calcium (Ca) and total nitrogen (N) content due to the compost application.The findings suggest that a composted equal-volume mix of BSG and PD may serve as an effective organic amendment for enhancing the yield of short-duration leafy vegetables like amaranth in coarse-textured soils of the humid tropics.