Agroecosystems Lab

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The impact of elevated CO2 on rhizodeposition and N cycling under wheat and corn

Photo of isotopic Nitrogen uptake by leafThis project aims at determining how elevated CO2 affects rhizodeposition and the cycling of rhizodeposited N under C3 and C4 plants and how cultivated genotypes of Triticum turgidum and Zea mays versus their wild progenitors responded to elevated CO2. By constructing an N transfer experiment we could directly assess cycling of the rhizodeposited N and trace the fate of rhizodeposited N in the soil and into receiver plants. Biomass production, rhizodeposition and cycling of root borne N of maize genotypes was not affected by elevated CO2. However, elevated CO2 stimulated above- and belowground biomass production of the wheat genotypes on average by 38%, and increased rhizodeposition and immobilization of root derived N on average by 30%. In addition, elevated CO2 reduced mineral 15N and re-uptake of the root derived N by 50 %.This study shows that elevated CO2 may enhance progressive N limitation by increasing N rhizodeposition and subsequent immobilization of the root derived N.