1. Ali H, Khan E, Sajad MA (2013) Phytoremediation of heavy metals—concepts and applications. Chemosphere 91:869–881
2. Amoakwah E, Van Slycken S, Tack FMG, Essumang D (2013) Assessing the extraction efficiency of CaCl2 and Rhizon extraction methods after the application of organic matter and CaCl2 as soil amendments to enhance the mobility of Cd and Zn. J Environ Anal Toxicol 3(2)
3. Amoakwah E, Van Slycken S, Essumang DK (2014) Comparison of the solubilizing efficiencies of some pH lowering (sulphur and (NH4)2SO4) amendments on Cd and Zn mobility in soils. Bull Environ Contam Toxicol 93:187–191
4. Azeez JO, Adeleye OA, Oyinlola RO (2016) The effect of sulfur and urea on the heavy metal extraction by african wild sunflower (Tithonia diversifolia) in an artificially contaminated soil. Commun Soil Sci Plant Anal 47:1940–1949
5. Azimzadeh Y, Shirvani M, Shariatmadari H (2016) Rhizosphere and green manure effects on soil chemical attributes and metal bioavailability as a function of the distance from plant roots in mono and mixed corn and canola cultures. Arch Agron Soil Sci 62:1066–1081