High crop yields depend on the continuous input of orthophosphate (PO 4 ĝ̂'3)-based fertilizers and herbicides. Two major challenges for agriculture are that phosphorus is a nonrenewable resource and that weeds have developed broad herbicide resistance. One strategy to overcome both problems is to engineer plants to outcompete weeds and microorganisms for limiting resources, thereby reducing the requirement for both fertilizers and herbicides. Plants and most microorganisms are unable to metabolize phosphite (PO 3 ĝ̂'3), so we developed a dual fertilization and weed control system by generating transgenic plants that can use phosphite as a sole phosphorus source. Under greenhouse conditions, these transgenic plants require 30ĝ€"50% less phosphorus input when fertilized with phosphite to achieve similar productivity to that obtained by the same plants using orthophosphate fertilizer and, when in competition with weeds, accumulate 2ĝ€"10 times greater biomass than when fertilized with orthophosphate.