EFFECT OF RICE STRAW BIOCHAR AND COMPOST APPLICATION AT DIFFERENT RATIOS ON HEAVY METALS IMMOBILIZATION IN THE CANOLA PLANTS GROWN IN CONTAMINATED SOIL

Industrial activities can contribute to the heavy metal accumulation in soils, which could potentially threaten human health, agricultural crop productivity and the environment. This research was conducted to use metal uptake and spectroscopic analysis (X-Ray Diffraction (XRD), Energy Dispersive spectroscopy by X-rays (EDX) and Fourier Transmission Infrared Spectroscopy (FTIR) to evaluate the effect of application of both rice straw biochar and compost with different ratios on heavy metal immobilization in the canola plants grown in the contaminated soil. The results showed that the Cd, Pb, Ni and Zn uptake in the root and shoot of canola plants significantly decreased with the addition of rice straw compost (RC) and biochar (RB) to contaminated soil. The addition of 1% mixture of RC and RB gives the most effective immobilizing metals as 100% and 74.2%, reduction in Cd and Pb accumulation by canola shoots, respectively. The biochar and compost obtained from rice straw showed high carbon content, silica and a high absorption character. The use of spectroscopic analysis observed the precipitation, inner-sphere complex reaction and electrostatic attraction are the dominating mechanism for heavy metal immobilization with organic amendments. Our results indicate that the metal uptake is considered to be the effective tool to assess the efficiency of immobilizing agents on metal phyto-availability.