Effects of different planting distances and fertilizer use on remediation of cadmium contaminated farmland by intercropping of Pumpkin and amaranth hypochondriacus L.

Soil cadmium pollution has become one of the most serious pollution problems of farmland soil in China. Selecting suitable plants for intercropping can restore Cd contaminated soil while ensuring safe crop production. Through field and cement pool experiments, the crop growth and Cd uptake of pumpkin-amaranth intercropping system planted with different densities and different fertilizer treatments were studied. Field experiment results showed that the Cd content of pumpkin in different systems were lower than national food safety standard (0.05 mg kg − 1 ). In the IN-1 (4 pumpkin plants intercropped with 200 amaranth plants) and IN-2 (4 pumpkin plants intercropped with 400 amaranth plants)systems, the single plant Cd concentration of amaranth increased by 32.43% and 25.25%, respectively, compared with that monocropping system ( P <  0.05). The IN-2 system had the highest equivalent ratio of heavy metal removal (3.08), indicating that this planting method had a great advantage in heavy metal removal. All the pumpkins treated with four kinds of fertilizers in cement pool experiment could achieve safe production, and chicken manure had the best promotion effect on the growth and yield of the two plants. The yield of pumpkin (per plant) treated with chicken manure is significantly higher than other treatments ( P <  0.05). Our results indicated that pumpkin-amaranth intercropping system is a good model for crop safety and remediation of Cd contaminated soil. At the same time, using 4 pumpkin and 400 amaranth plants intercropping and applying chicken manure fertilizer was a good way to strengthen the intercropping system.