Field evidence of cadmium phytoavailability decreased effectively by rape straw and/or red mud with zinc sulphate in a Cd-contaminated calcareous soil.

Bo Li,Dongpu Wei,Shibao Chen,Junxing Yang,Jumei Li,Yibing Ma,Wenju Liang

doi:10.1371/journal.pone.0109967

Abstract

To reduce Cd phytoavailability in calcareous soils, the effects of soil amendments of red mud, rape straw, and corn straw in combination with zinc fertilization on Cd extractability and phytoavailability to spinach, tomato, Chinese cabbage and radish were investigated in a calcareous soil with added Cd at 1.5 mg kg−1. The results showed that water soluble and exchangeable Cd in soils was significantly decreased by the amendments themselves from 26% to 70%, which resulted in marked decrease by approximately from 34% to 77% in Cd concentration in vegetables. The amendments plus Zn fertilization further decreased the Cd concentration in vegetables. Also cruciferous rape straw was more effective than gramineous corn straw. In all treatments, rape straw plus red mud combined with Zn fertilization was most effective in decreasing Cd phytoavailability in soils, and it is potential to be an efficient and cost-effective measure to ensure food safety for vegetable production in mildly Cd-contaminated calcareous soils.

Highlights

Increasing cadmium (Cd) accumulation in vegetables is a growing concern globally because of increased fertilizer- and biosolids-borne Cd in soils [1,2,3]
Compared with the vegetable grown in unamended soil, the concentrations of Cd in the edible parts of the four vegetables were reduced with amendment treatments, and the reduction (% of control) was significantly different (P,0.05) among the different treatments
The reduction of Cd in vegetables ranged from 37% to 76% for spinach, and from 34% to 63% for tomato, and from 59% to 76% for Chinese cabbage, and from 61% to 77% for radish, with the lowest for corn straw (CS) treatment and the highest for rape straw (RS)+ red mud (RM) treatment

Summary

Introduction

Increasing cadmium (Cd) accumulation in vegetables is a growing concern globally because of increased fertilizer- and biosolids-borne Cd in soils [1,2,3]. The possibility of Cd immobilization in soils through the addition of different amendments or sorbent, has been extensively investigated in order to reduce the risk of groundwater contamination, plant uptake, and exposure to living organisms [6,7,8,9] Among these amendments or sorbents, red mud (RM), a by-product of aluminium (Al) manufacturing, can be very effective in increasing Cd sorption and decreasing soluble Cd concentrations in Cd-contaminated and acidic soils under pot trials [10,11,12,13] and field studies [14,15], and lead to a reduction in

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Discussion

Conclusion