[Effects of sewage sludge vermicompost on the growth of marigold]

The 1:1, 2:1, 3:1, 4:1, 5:1, and 1:0 mixtures of sewage sludge and cattle dung were treated with earthworm Eisenia foetida, and then, mixed with black soil in the proportions of 10%, 20%, and 30% (dry mass) to investigate the effects of the vermicompost on the marigold plant height, stem diameter, leaf number, branch number, aboveground biomass, underground biomass, ratio of root to shoot, flower bud number, flower yield, flower diameter, and flower biomass. An obvious promotion effect of the vermicompost was observed on the growth of marigold. The smaller the ratio of sewage sludge to cattle dung, the better the growth of marigold; while a higher proportion of the vermicompost to soil would inhibit the marigold growth. In this study, a proportion of 20% vermicompost to soil was the best for the growth of marigold.