Effective Placement Methods of Vermicompost Application in Urban Tree Species: Implications for Sustainable Urban Afforestation

Abstract

Knowledge on growth and nutrient uptake characteristics of urban trees and effective strategies to grow trees can help accomplish the goal of urban afforestation initiatives in a sustainable way. Thus, the study investigated the effects of different vermicompost (VC) application placements on the growth and nutrient uptake of three contrasting tree species (fast-growing Betula platyphylla and Larix kaempferi and slow-growing Chamaecyparis obtusa) to provide implications for growing tree stocks for sustainable urban afforestation programs. Five placement methods were used in the greenhouse trial: no fertilization (CON), surface placement (VCs), subsurface placement at 6-cm depth (VCc), bottom placement (35-cm depth (VCb)), and mixed with soil (VCm). We measured the growth parameters such as height, root collar diameter (RCD), and biomass and analyzed foliar nutrient concentrations in response to different placement treatments of VC. Relative height growth was the highest at VCc (132% (B. platyphylla), 114% (L. kaempferi)) and VCs ((57%) C. obtusa). Significant improvement in aboveground and belowground biomass growth of all species at VCs and VCc compared to the other treatments was also observed. Generally, VC treatments significantly increased N concentration compared to CON in all species. In conclusion, fertilizing the fast- and slow-growing urban tree species using VCs and/or VCc is relevant to growing high quality planting stocks for sustainable urban afforestation purposes.