Interactions between regenerative strategies and edaphic, climatic and topographic factors mediate mitigation or exacerbation of soil and crop toxicity in global cadmium contaminated lands

Cadmium (Cd) contamination in agroecosystems is a global concern, due to its negative influence on soil health and crop performance. Regenerative strategies have been widely recognised as vital to improve soil quality and crop yields. Yet strategies are needed that also mitigate rather than exacerbate the impacts of Cd contamination. In this context, interactions between regenerative strategies, and edaphic, climatic and topographic factors are poorly understood. This study presents a meta-analysis with effect size statistics, evaluating the interactions between regenerative strategies (biochar, manure and compost), non- regenerative strategies (sewage-sludge and fertilizer), soil properties (pH, SOM and Cd levels), climatic factors (temperature and precipitation), and elevation. In acidic or high SOM soils, fertilizer increased Cd uptake by 50% to 76%. However, biochar or compost addition in these soils reduced Cd uptake. Under high Cd contamination, biochar application increased shoot biomass, but fertilizer application decreased shoot-biomass. The application of fertilizer or sewage-sludge under higher temperatures increased Cd uptake, whereas biochar reduced Cd uptake. At wet sites, fertilizer addition increased soil Cd accumulation. At high elevations, biochar was more effective than manure at reducing Cd accumulation. We conclude that there are complex interactions between regenerative strategies and environmental conditions; determining impacts on soil and crop health. The interactions between environmental factors and use of sewage-sludge or fertilizer could exacerbate soil and plant Cd toxicity. Regenerative strategies, especially biochar, could mitigate Cd toxicity in agroecosystems. • Meta-analysis showed maximum Cd toxicity at 50 g kg −1 sewage-sludge input. • Biochar addition in acidic and high-SOM soils reduced Cd uptake. • In acidic soils, fertilizer application increased Cd uptake by 50%. • Biochar increased shoot biomass more strongly at higher than lower temperatures. • At higher elevation, biochar was more effective than manure at reducing soil Cd.