Basalt and biochar effects on plant health, human health, and carbon cycling in urban agroecosystems

Soil amendments had few significant effects on plant PTE uptake and health. (2) Human health risks: This study characterised Pb ingestion risks in soils and vegetables from no-crop, lettuce, carrot, and garlic agrisystems amended with 5%w/w digestate biochar, using the Unified BARGE Bioaccessibility Method and health risk indices. Biochar reduced bioaccessible soil Pb in some no-crop, carrot, and garlic agrisystem soils, though had no significant effects on vegetable Pb ingestion risks.

(3) Carbon cycling: This study investigated the influence of digestate biochar and basalt dust on soil carbon stock, soil carbon and nitrogen isotopes, and soil CO2 efflux in clover and mustard agrisystems over 12 months. Amendments had minimal effect on stored soil carbon stock and isotopes, however basalt increased soil carbon efflux compared to control. Ultimately, this collective research indicated that soil amendments do not universally improve NBS efficacy.

Here, locally-sourced amendments may have been less effective as amendment characteristics are similar to soil characteristics. This highlights the need to undertake specific site soil characterisations to support effective implementation of urban NBS amendments. <br><br><i>Thesis is embargoed until 31 December 2030.</i>