We evaluated the potential of As-hyperaccumulator Pteris vittata (PV) to remove As from As-contaminated soils over five harvests in 2.5 years in a field experiment. We tested the hypothesis that a P-limiting environment would enhance PV growth and As uptake owing its unique ability to take up P under As-rich environment. In Dec. 2009, PV was transplanted to three As-contaminated soils (pH of 5.5-7.2) containing 25 - 129 mg kg-1 As, which was amended with sparingly-soluble phosphate rock (PR-soil) or soluble P fertilizer (P-soil). During the 2.5-year, PV obtained sufficient P (1,882 vs. 2,225 mg kg-1) from PR-soils, attributing to its increase in root biomass (33%) and root exudation (53%) compared to P-soils. In addition, its frond biomass increased by 20% consecutively with each harvest (six month interval) from 18 to 36 g plant-1 and its frond biomass in PR-soils (52.2 g plant-1 year-1 or ~12 mt ha-1 year-1) averaged 39% more than that in P-soils. To our knowledge, this represented the largest PV frond biomass reported, demonstrating the effectiveness of PR in enhancing PV growth. In addition to biomass increase, PV in PR-soils took up ~1.5 times more As in fronds (2,540, 780, and 920 mg kg-1) than those from P-soils (1,740, 570, and 400 mg kg-1). The low available P in PR-soils induced substantial plant growth and As uptake by PV. This translated into significantly more As removal from soil, averaging 48% reduction in PR-soils and 36% in P-soils in 2.5 years. With multiple harvests and PR amendments, our results showed As removal by PV from contaminated soils was ~7 times faster than published studies.
