Biochar as agricultural alternative to protect the rice plant growth in fragile sandy soil contaminated with cadmium

Abstract Contamination by cadmium (Cd) is a serious problem in fragile sandy soils. In these soils, the high amount of sand fractions with uncharged surface and low organic matter content cause the high mobility of Cd. Biochar has been shown to be highly promising for mitigating adverse effects on soils, but little is known about its role in Cd-contaminated fragile soils. The aim of this study was to obtain biochar from different biomasses and evaluate their effects on root growth in rice plants and their protective effects against Cd stress in a Planosol. Three biochar obtained were characterized by 13C NMR and elemental composition. In the first experiment, biochar was added to the Planosol at different ratios (1.0%, 2.0%, and 3.0%), and root growth and photosynthesis parameters were evaluated after 28 days of growth. In the second experiment, the plants were grown in a Planosol with biochar (3.0%) contaminated with Cd, and the plant antioxidative defense parameters were evaluated. Biochar at 3.0% stimulated the growth of plant roots, as well as the photosynthetic pigment contents. The biochar showed a protective effect on the rice plants, decreasing the reactive oxygen species and malondialdehyde content and increasing the membrane permeability preservation when plants were subjected to Cd stress. Biochar may be an ecologically sustainable material for the preservation of soils and plants under conditions of fragile soils.