Performance of vermicompost leachate for the fertilization of two native plants

COGOLLO-RUEDA, MAURICIO; DE CABO, LAURA; LUZ, MONTENEGRO; BASÍLICO, GABRIEL OMAR; LÓPEZ, ROMINA

Simposio; 5th International Symposium on Environmental Biotechnology and Engineering; 2016

The vermicomposting process of the organic fraction of municipal solid waste hasas a by-product a nutrient-rich leachate that could be used as fertilizer. However, insome cases, the leachate may be phytotoxic. The objective of this work is to evaluatethe performance of vermicompost leachate for the fertilization of two ornamental andnative woody species: Austroeupatorium inulifolium (shrub) and Erythrina crista-galli(tree). The leachate was produced from composting of household organic waste andwas characterized by high pH (>8.00), high electrical conductivity (EC) (22.3 mS/cm),low levels of N and P (144 mg/l and 50.8 mg/l, respectively) and high concentrationof potassium (5430 mg/l). An assay was performed for each species, byquadruplicate. For A. inulifolium the experiment consisted in two treatments, aControl where the pots were irrigated with deionized water (dw) and a ?10%L?treatment, irrigated with 10% v/v leachate:dw solution. For E. crista-galli theexperiment consisted in five treatments: a Control irrigated with dw and irrigation with5%L (v/v), 10%L (v/v), a commercial chemical fertilizer (CF) and a commercialchemical and biological fertilizer (CBF). In both experiments was used 400 g per potof the same commercial substrate. Seedlings and seeds were used for A. inulifoliumand E. crista-galli, respectively. After 51 days for A. inulifolium and 107 days for E.crista-galli, plant height, stem diameter and above ground tissue, below groundtissue and total fresh weight were measured. Also, pH, EC and organic mattercontent (%OM) of the substrate was measured.Total height, stem diameter and fresh weight of A. inulifolium were no modified bythe irrigation with leachate (10%), although the %OM, pH and EC were higher thancontrol. For E. crista-galli, significant differences between treatments were observedin the case of total height (ANOVA; p=0.034), above ground tissue weight (p=0.002)and total weight (p=0.006). Tukey post hoc comparisons show no significantdifferences between control and leachate treatments and significant differences(p<0.05) between CF and treatment 10%L (total height), CF and 5%L and 10%L(total weight) and CF and 5%L, 10%L and CBF (above ground tissue weight).Dunnett post hoc comparisons show significant differences between CF and controlfor above ground tissue weight (p=0.040) and total weight (p=0.028).Although the use of leachate did not significantly improve plant growth in any case,neither inhibited it. The irrigation of substrate or soil with leachate solution at theconcentrations studied could improve several characteristics of these matriceswithout causing phytotoxic effects.