Alleviation of cadmium (Cd) toxicity and minimizing its uptake in wheat (Triticum aestivum) by using organic carbon sources in Cd- spiked soil Muhammad Zia ur Rehman a , Muhammad Rizwan b, * , Amjad Hussain c , Muhammad Saqib a , Shafaqat Ali b , Muhammad Irfan Sohail a , Mahnoor Shafiq a , Farhan Hafeez d a Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad, 38040, Pakistan b Department of Environmental Sciences and Engineering, Government College University, Allama Iqbal Road, 38000, Faisalabad, Pakistan c Higher Education Commission, Islamabad, Pakistan d Department of Environmental Sciences, COMSATS Institute of Information Technology (CIIT), Abbottabad, Pakistan article info Article history: Received 16 April 2018 Received in revised form 16 May 2018 Accepted 1 June 2018 Keywords: Cadmium Organic amendments Rice husk biochar Lignite Farmyard manure abstract Cadmium (Cd)-contamination of agricultural soils has been receiving attention worldwide due to its entry into food crops such as wheat (Triticum aestivum L.). Little is known regarding the use of organic carbon (OC) sources in alleviating Cd toxicity in cereals. The current experiment was aimed to study the effects of different OC sources on the Cd accumulation by wheat. A pot study was conducted to deter- mine the effects of rice husk biochar (RHB), farmyard manure (FYM), and lignite (LT) either alone or in combination on crop growth, Cd bioavailability and health risk assessment. The results proved that the application of OC sources like RHB, FYM, and LT either alone or in combination were highly effective in enhancing the wheat growth and yield as well as in minimizing the phyto-available fraction of Cd and its transfer to edible tissue of wheat. The RHB was the most efficient source in enhancing the plant growth and reducing the Cd concentration in wheat tissues. RHB increased grain yield by 91% and decreased Cd concentration in shoot, roots, grains, and bioavailable fraction of Cd by 67, 69, 62.5, and 74% than control, respectively. The RHB reduced the daily Cd uptake and health risk index in adults in comparison to control. Overall, where un-amended soil resulted in diminished plant productivity, the application of other OC sources also significantly proved their potential to enhance the dry weight and grain yield, suggesting that these OC sources may be used aiming to minimize the Cd concentration in crops. However, there is still a need to explore the potential of different OC sources in combination with other frequently available amendments for their large scale implementation in metal-contaminated soils. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction The main sources of toxic trace element accumulation in agri- cultural soils are both anthropogenic and geogenic activities which might be the main source of heavy metal transfer into food chain (Rizwan et al., 2016a; Rehman et al., 2015; Yin et al., 2016). Heavy metals are reported to cause toxicities in living things, mainly owing to their persistent and toxic and non-biodegradable nature in ecosystem (Bolan et al., 2014; Adrees et al., 2015a; Yousaf et al., 2016). Among the toxic heavy metals, cadmium (Cd) is one of the most hazardous element in environment (Nagajyoti et al., 2010; Rizwan et al., 2018). The main sources of Cd accumulation in agri- cultural soils are modern agricultural practices like application of raw industrial and municipal effluents, sewage sludges, phosphate fertilizer as well as mining waste incineration and atmospheric deposition (Murtaza et al., 2015; Qayyum et al., 2017). The main route of Cd entrance into plants is via the roots which could absorb the dissolved Cd in soil solution (Rizwan et al., 2016d). The reduc- tion in root growth is the first toxic effect of Cd due to its direct contact with roots in the growth medium (Rizwan et al., 2016b). The Cd has been reported to cause the stunted plant growth, reduced photosynthesis as well as the yield and toxicity symptoms * Corresponding author. E-mail address: mrizwan@gcuf.edu.pk (M. Rizwan). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol https://doi.org/10.1016/j.envpol.2018.06.005 0269-7491/© 2018 Elsevier Ltd. All rights reserved. Environmental Pollution 241 (2018) 557e565