Effects of Different Fertilization Patterns on Available Cadmium and Copper in Acidic Soil and Its Impact on Cd and Cu Accumulation in Head Lettuce

PurposeTo study the effects of different fertilization patterns on reducing the risk of heavy metal pollution in farmland soil and the content of heavy metals in vegetables, so as to provide reference for the safe utilization of heavy metal polluted farmland soil.

MethodA field experiment was conducted to investigate the effects of organic fertilizer, chemical fertilizer and their combined application with calcium carbonate powder on the dynamic changes of pH value and available content of Cd and Cu in acidic soil, the growth of head lettuce and the enrichment of Cd and Cu in its edible parts.

ResultsCombined application of organic fertilizer and calcium carbonate powder could increase the soil pH, while the application of chemical fertilizer reduced the soil pH. Compared with the control, the effect of application of organic fertilizer 22.5 t/hm² and combined application of organic fertilizer 22.5 t/hm²+calcium carbonate powder 1.5 t/hm² on reducing the content of available Cd and Cu in soil was more obvious at 45 days (the content of available Cd in soil decreased by 38.41% and 43.12%, respectively, and the content of available Cu in soil decreased by 54.79% and 53.79%, respectively); the application of chemical fertilizer was not conducive to the reduction of the content of available Cd and Cu in soil. Compared with the control, the application of organic fertilizer 22.5 t/hm² and the combination of organic fertilizer 22.5 t/hm²+calcium carbonate powder 1.5 t/hm² increased the yield of head lettuce by 184.33% and 153.31%, respectively; the content of Cd in lettuce decreased by 60.17% and 36.40%, respectively; the content of Cu in lettuce decreased by 47.27% and 19.35%, respectively; the application of chemical fertilizer could not reduce the contents of Cd and Cu in head lettuce.

ConclusionThe application of organic fertilizer and the combination of organic fertilizer and calcium carbonate powder can improve soil pH, reduce the bioavailability of soil Cd and Cu, and improve the yield and safety quality of vegetables. The results can provide reference for reducing the risk of Cd and Cu pollution in farmland in similar areas and improving the safety and quality of vegetables.