Remediation Effects of Different Composite Materials on Cadmium-Contaminated Farmland Soil

Abstract

A pot experiment was conducted to study the application effects of three composite materials, namely SC (lime:organic compound fertilizer=2:3), LS (ferrous sulfate:lime=1:1) and LB (ferrous sulfate:biochar in combinations of 1:1, 1:2, 1:3, 1:4 and 1:5), on soil Cd bioavailability, Cd cumulative distribution in different wheat organs, and wheat yield. The results indicated that:① Addition of composite materials all significantly decreased the soil available Cd content by 50.2%-81.8% (SC), 29.4%-48.1% (LS), and 18.7%-42.2% (LB). Composite materials significantly increased soil pH by 1.37-2.28 (SC), 0.41-0.86 (LS), and 0.14-0.17 (LB) units. ② The Cd cumulative distribution in different wheat organs were in the order of root > leaf > stem > glume > grain. The translocation abilities of Cd in different organs were in the order of root > glume > stem and leaf. ③ Compared with the control, 0.67% SC addition and 0.67% LS addition significantly increased the wheat yields by 56.4% and 51.2%; LB addition significantly increased wheat yield by 39.6% to 51.2%. ④ The correlation analysis showed that soil pH was significantly negatively correlated with soil available Cd and Cd contents in different wheat organs. There were significant positive correlations between soil available Cd and Cd contents in different wheat organs, and the correlation coefficients were 0.711 (grain), 0.817 (glume), 0.593 (stem), 0.630 (leaf) and 0.622 (root). Meanwhile, there is also a significant positive correlation between Cd content in different wheat organs. ⑤ Comprehensively, the addition of 0.93% SC increased soil pH by a maximum of 2.28 units, and the soil available cadmium content was decreased by a maximum of 81.8%. Therefore, adding 0.93% SC was the most suitable treatment for repairing and controlling the Cd pollution in farmland soil.