| Sumario: | 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 © 2016 John Wiley and Sons, Ltd.
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