This invention provides a method for remediating
cadmium-contaminated farmland soil using a multifunctional slow-release granule combined with
EDDS-enhanced Bidens trifoliata. Before
sowing, the multifunctional granules are applied to the
cadmium-contaminated soil, followed by
irrigation with
calcium nitrate solution after
sowing Bidens trifoliata. On day 40, a
melatonin aqueous solution is applied as a top dressing; and on days 50-60, a mixed
aqueous solution of
EDDS and CaCl2 is sprayed. The multifunctional granules, from the inside out, consist of an alkali-modified
biochar-supported iron-based
oxide core, a
urea-
formaldehyde-PASP functional layer, and a
calcium alginate shell. This invention achieves highly efficient remediation of
cadmium-contaminated farmland soil by Bidens trifoliata through the temporal
coupling of cadmium pre-fixation and slow-release
nitrogen supply by the multifunctional granules,
melatonin-promoted growth, and synergistic activation by
EDDS / CaCl2. It is simple to operate, highly efficient, and can effectively shorten the remediation cycle of moderately and severely cadmium-contaminated farmland soil in
arid and semi-
arid regions, showing promising prospects for widespread application.