Liebig's law of the minimum applied to a greenhouse gas: Alleviation of P-limitation reduces soil N2O emmission

Summary

Emission of the greenhouse gas (GHG) nitrous oxide (N2O) are strongly affected by nitrogen (N) fertilizer application rates. However, the role of other nutrients through stoichiometric relations with N has hardly been studied. We tested whether phosphorus (P) availability affects N2O emission. We hypothesized that alleviation of plant P-limitation reduces N2O emission through lowering soil mineral N concentrations. We tested our hypothesis in a pot experiment with maize (Zea mays L.) growing on a P-limiting soil/sand mixture. Treatment factors included P and N fertilization and inoculation with Arbuscular Mycorrhizal Fungi (AMF; which can increase P uptake). Both N and P fertilization, as well as their interaction significantly (P <0.01) affected N2O emission. Highest N2O emissions (2.38 kg N2O-N ha(-1)) were measured at highest N application rates without P fertilization or AMF. At the highest N application rate, N2O fluxes were lowest (0.71 kg N2O-N ha(-1)) with both P fertilization and AMF. The N2O emission factors decreased with 50 % when P fertilization was applied. Our results illustrate the importance of the judicious use of all nutrients to minimize N2O emission, and thereby further underline the intimate link between sound agronomic practice and prudent soil GHG management.