Compost application increases the ecological dose values in a non-calcareous agricultural soil contaminated with cadmium.

Soil cadmium (Cd) pollution resulting from anthropogenic activities has become a major concern for microbial and biochemical functions that are critical for soil quality and ecosystem sustainability. Organic amendments can reduce Cd toxicity to the microbial community and enzymatic activity in Cd-polluted soils and thus would increase the ecological dose (ED) values. However, there has been less focus on the effect of organic amendments on microbial and biochemical responses to Cd toxicity in non-calcareous soils using the concept ED. The aim of this study was to assess the impact of compost application on microbial activity, microbial biomass, turnover rates of carbon and nitrogen, and enzymatic activities as the key ecological functions in a non-calcareous soil spiked with different Cd concentrations (0-200 mg kg). Results showed that soil amendment with compost decreased Cd availability by 48-76%, depending on the total soil Cd content. The application of compost reduced the negative influence of Cd eco-toxicity on most soil microbial and biochemical functions by 20-122%, depending on the Cd level and the assay itself. The ED values, derived from the sigmoidal dose-response and kinetic models, were 1.10- to 2.24-fold higher in the compost-amended soils than the unamended control soils at all Cd levels. In conclusion, the potential risks associated with high levels of Cd pollution can be alleviated for microbial and biochemical indicators of soil quality/health with application of 2500 kg ha compost as a cost-effective source of organic matter to non-calcareous soils. The findings would have some useful implications for organic matter-limited non-calcareous soils polluted with Cd.