Bioavailability of Sodium and Trace Metals under Direct and Indirect Effects of Compost in Urban Soils

Abstract

The contamination of urban soil with sodium (Na) and trace metals can be one of the major concerns for groundwater contamination and street tree health. The bioavailability of Na, copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in urban soil amended with 0, 5, and 10% w/w compost was evaluated at none, medium, and high contamination levels of soil mixtures. The relationship between soil properties, compost addition, contamination level and metal uptake by barley ( L.) was determined using multivariate linear regression and path analysis. The results indicated the direct negative effect of compost on metal absorption possibly through specific complexation for Cu, Zn, Cd, and Pb. Compost can also affect the absorption of Na and Cd indirectly by means of cation exchange capacity (CEC) and pH. The degree of soil contamination with metals can affect the competition of cations for the complexing sites of the soil mixtures and, therefore, can induce changes in metal availability for plants. Compost addition to the soil also increased nutrient availability, except for ammonium (NH) and nitrate (NO). We concluded that in the short term, the addition of compost significantly reduced metal bioavailability and improved nutrient availability. However, more studies are required to monitor the long-term ability of the compost to reduce Na and trace metal bioavailability in urban soil.

Street Tree Structure, Function, and Value: A Review of Scholarly Research (1997–2020)

“…), [81,82]), leaf-gas exchange [83], biomass production [84]. Other research isolated specific biophysical contributors to establishment and growth, such as overall site conditions [22], pavement material [85], soil compaction [86], aeration [87], and different forms of soil amendments like biochar [88], compost [89], or engineered soils [90]. Additionally, the persistence of certain hydro-logic conditions, like water retention [91] or drought [92], as well as the presence of fungal colonies [93] have been subject to research.…”