Soil phosphorus sorption capacity dictates the effect of elevated CO2 on soil and plant critical phosphorus levels for wheat growth

Abstract

AbstractBackgroundRising atmospheric CO2 concentrations can increase crop yields; however, it is poorly understood if plants require higher phosphorus (P) inputs to support increased production. In addition, soils with contrasting P‐sorption capacities may alter plant response to elevated CO2.AimsWe examined the effect of elevated CO2 on the critical concentrations of soil available P and shoot P for plant growth in soils with contrasting P‐sorption capacities.MethodsResponse curves to P applications were generated for wheat (Triticum aestivum L.) grown in a low P‐sorption Sodosol and a high P‐sorption Ferrosol. Plants were grown for 5 weeks under ambient (400 ppm) and elevated (800 ppm) CO2 concentrations at nine P application rates. The concentrations of plant P and soil P extracted using Olsen, Bray and Resin methods were analysed.ResultsElevated CO2 increased biomass production in both soils. Plants grown in the Ferrosol but not in the Sodosol required higher P inputs to achieve maximum biomass production in response to elevated CO2. Elevated CO2 increased the critical Olsen‐P but decreased the critical Bray‐P concentrations for shoot biomass production in the Ferrosol. Elevated CO2 decreased the critical P concentration in shoots of plants grown in the Sodosol but not in the Ferrosol.ConclusionsThe effect of P fertilisation on plant response to elevated CO2 depends on soil type. Elevated CO2 also potentially alters P acquisition mechanisms of plants, which requires adjustment of the critical P concentration in shoot and in soil depending on soil P‐sorption capacity and the analytical method used to assess P availability.