Jump to Main Content
Ammonium-based fertilizers enhance Cd accumulation in Carpobrotus rossii grown in two soils differing in pH
- Cheng, Miaomiao, Wang, Anan, Tang, Caixian
- Chemosphere 2017 v.188 pp. 689-696
- Carpobrotus, X-ray absorption spectroscopy, ammonium, ammonium sulfate, bioavailability, cadmium, cadmium chloride, calcium chloride, fertilizer application, halophytes, nitrification inhibitors, nitrogen, nitrogen fertilizers, pH, phytoremediation, potassium nitrate, rhizosphere, roots, shoots, soil, urea
- Nitrogen fertilization has been shown to improve Cd uptake by plants but there is little information on the effect of N form. This study examined the effects of N form on Cd bioavailability and phytoextraction in two soils differing in pH. Plants of halophytic species Carpobrotus rossii were grown in an acidic Sodosol [pH (CaCl2) 4.9] and a neutral Vertosol (pH 7.2) spiked with 20 mg kg⁻¹ Cd as CdCl2. Three N forms, KNO3, (NH4)2SO4 and (NH2)2CO at a rate of 24 mg N kg⁻¹ were applied at weekly intervals, together with nitrification inhibitor dicyanodiamide. Cadmium availability was measured, and Cd speciation in the rhizosphere analysed using synchrotron-based X-ray absorption spectroscopy. The uptake, translocation and accumulation of Cd in plants were also assessed. The reduced N forms (NH4⁺ and urea), compared to NO3⁻-N, decreased rhizosphere pH by 0.25 units in Sodosol and 0.72 units in Vertosol, but decreased Cd-phosphate (by 23%) only in the Vertosol. Moreover, the reduced N forms increased the extractable Cd concentration in the rhizosphere of the Vertosol by 92% and of the Sodosol by 14%. They increased root Cd concentration by 70% and Cd uptake per unit root length by 40% in the Vertosol, and increased the translocation of Cd from the roots to the shoots by 76% in the Sodosol. The results suggest that the supply of NH4⁺-based N favors Cd phytoextraction in C. rossii.