Fertilization of field crops has an impact on soil nitrogen (N) emissions while increasing crop productivity. Nitrous and nitric oxide emissions (N2O and NO, respectively) affect the radiative balance of the atmosphere (N2O) and local air quality (NO). These emissions, however, are influenced not only by N input but also by the rhizosphere of the crop. A mesh house experiment was set up with different treatments to investigate how the rhizosphere affects soil N2O and NO emissions. This encompassed 4 treatments: (A) fertilized soil without carrots; (B) carrots without fertilizer addition; (C) carrots with fertilizer addition; and (D) carrot removal (after 60 days) with fertilizer addition. Through the growth period, we measured soil N2O and NO emissions as well as microbial community composition. For the last treatment, we plucked the above and belowground portions of the carrots in half of the fertilized plots after 60 days of growth. We then assessed the changes in soil trace gas emissions and microbial activity. We observed that the carrot rhizosphere enhances soil N2O emissions but does not affect soil NO flux. We also observed the distinct effects of carbon exudate dynamic behavior, which resulted in a change in carbon availability for soil microbes involved in denitrification. Importantly, both the (A) treatment (no carrots) and (B) treatment (no fertilization) exhibited no significant differences in soil trace gas emissions, implying that the presence or absence of plants did not affect emissions.
Ms. Vanessa Victor
Rhizosphere Priming Soil Nitrous Oxide but not Nitric Oxide Emissions
Ben Gurion University of the Negev, Israel