Effect of the Concentration of Vermicompost Aqueous Extract (Vermicompost Tea) On Pak-Choi (Brassica rapa, Chinensis Group) Yield, Quality, and Soil Biological Properties

Two greenhouse trials and two field trials were conducted to investigate the effects of vermicompost tea (aqueous extract) on growth, tissue N and phytonutrient content of pak choi (Brassica rapa chinensis), and on soil biological properties.  In the greenhouse experiments, plants were fertilized with chicken manure-based thermophilic compost.  In the field trials, three fertilizer treatments: (i) rendered meat by-product (Tankage), (ii) soluble fertilizer (16:16:16) and (iii) chicken manure-based thermophilic compost were applied. Aerated vermicompost teas were prepared using chicken manure-based vermicompost and water at various ratios. Pak choi plants were treated with 10%, 5%, 3% and 1% vermicompost teas in the greenhouse experiments; and 10% and 5% teas in the field trials. Applications of vermicompost tea significantly increased plant growth, N content, total carotenoids and total glucosinolates in plant tissue; this response was greatest in the chicken manure-fertilized treatments. Such positive responses were associated with increased N uptake. Vermicompost tea also improved soil respiration and dehydrogenase activity. Plant growth, phytonutrient content and microbial activities in soil increased with increasing concentrations of vermicompost tea. The findings suggest that vermicompost tea could be used to improve plant nutrient status in vegetable production and enhance soil biological properties.