Phytoremediation of Cd-contaminated farmland soil via various Sedum alfredii-oilseed rape cropping systems: Efficiency comparison and cost-benefit analysis

Phytoremediation is a green technology for heavy metal removal from contaminated soil, and its remediation efficiency and economic feasibility in field trial should be evaluated before large-scale application. However, there is still lacking relevant analysis, especially for phytoremediation with different cropping patterns. In the present study, we performed phytoremediation on slightly Cd-contaminated farmland soil via three cropping systems, i.e. Sedum alfredii monoculture, oilseed rape monoculture, and S. alfredii-oilseed rape intercropping. Dry weights of S. alfredii and oilseed rape were both enhanced under intercmpping pattern, while the highest total Cd extraction amount (148 g ha(-1)) were observed under S. alfredii monoculture. Furtherly, a cost-benefit analysis via Monta Carlo simulation in a ten-year lifetime was conducted. The benefits of S. alfredii monoculture and intercropping schemes would offset the total costs in 6 and 8 years, respectively. S. alfredii monoculture achieved a higher net present value of 1.88 x 10(4) US$ as compared with intercropping (9.53 x 10(3) US$). These results indicate that S. alfredii monoculture scheme could be a promising phytoremediation strategy for slightly Cd-contaminated soil owing to better remediation efficiency and economic feasibility. Moreover, the enhancement in mechanization level and the reduction of seedling cost could further improve its economic viability.

Automated summary

Phytoremediation is a promising strategy for slightly Cd-contaminated soil, with better remediation efficiency and economic feasibility found in Sedum alfredii monoculture. Cost-benefit analysis showed that the benefits of monocropping and intercropping schemes would offset the total costs in 6 and 8 years, respectively, with monocropping achieving a higher net present value.