Abstract:
Biosolids and Dairy Shed Effluent (DSE) can contain elevated concentrations of plant nutrients. DSE and biosolids application gave positive effects on forest tree species, which can subsequently provide economic returns through increased biomass and soil nutrients, while avoiding accumulation of biosolids derived contaminants above threshold values. However, at the same time biosolids, but not DSE, will lead to elevated concentrations of some trace elements in the plants. Results show that amending the low fertility soil with 2600 kg N ha-1 equivalent of biosolids and 200 kg N ha-1 equivalent of DSE improved the growth of both L. scoparium and K. robusta through higher production of biomass and increased of Ca, K, and S uptake. L. scoparium were growing better than K. robusta in combination with DSE, whereas they both gave same positive response on growth parameter in combination with biosolids. Biosolids and DSE application increased the uptake of certain essential trace-elements and contaminants including Cd, Cu, Mn, and Zn but did not result in unacceptable levels. Since biosolids may have influenced plant rhizodeposition, it is recommended for future studies to investigate plant root-microbe interactions with regard to plant element uptake.
