Forms of Nitrogen Alter Plant Phosphorus Uptake and Pathways in Rehabilitated Highly Alkaline Bauxite Processing Residue Sand uri icon

abstract

  • Understanding plant phosphorus (P) uptake and pathways is critical in the rehabilitation of degraded landscapes. This study investigated whether the uptake of P by Lolium rigidum was influenced by forms (inorganic and organic) of nitrogen (N) and whether the forms of N affected P loss by leaching in bauxite-processing residue sand (BRS). Gypsum amended BRS was grown with L. rigidum and fertilized with P [calcium di-hydrogen phosphate, Ca (H2PO4)(2)], plus different forms of N [e.g. control (CK without N addition, glycine (P-GL), ammonium (P-AS) and nitrate (P-KN))]. The experimental treatments were arranged in a complete randomized design. Aboveground biomass P under P-KN accounted for 47.4% of applied P, but only 26.0% and 25.0% under P-AS and P-GL, respectively. However, root P contents showed a different trend where P-AS (31.9%) was highest followed by P-GLY (23.0%) and P-KN (17.1%). Meanwhile, loss of P via leaching was minimal (<5% of applied P) regardless of treatment, which could be because of the high affinity of residue sand for P via specific adsorption sites. This was supported by high percentage recovery of applied P in BRS growth media under P-GLY (48.1%), P-AS (37.2%) and P-KN (32.0%). It is concluded that loss of P via leaching may not be a problem in BRS; however, limited plant P availability may be of more concern. Further, uptake of P by L. rigidum in alkaline BRS was found to be more efficient under nitrate-N fertilization. Understanding, however, the specific or associated mechanisms involved warrants further investigation. Copyright (C) 2016 John Wiley & Sons, Ltd.

publication date

  • 2017
  • 2017
  • 2017