Microplot Study with the Portable Flow through System and Soil Core Incubation for N2O Emissions Measurements.

Soil moisture and N fertilization are major factors affecting emissions of highly potent greenhouse gas nitrous oxide, which is the major contributor to climate change from agricultural land. A well-known substrate acetylene is commonly used in soil incubation studies for preventing nitrification and therefore eliminating respective pool of nitrous oxide by deactivating ammonia monoohygenase enzyme, which catalyzes ammonia oxidation process. We conducted a microplot study with Li-Cor 8100A long term chambers combined with the LGR 23r N₂O analyzer and a soil core incubation study with two levels of acetylene at variable moisture levels in order to determine the net N₂O emissions and nitrification and denitrification pools of N₂O. The study was conducted in the long term no-tillage site following spring wheat harvest in the fall 2014 at Palouse Conservation Field Station in Pullman, WA. Effects of aqua and ammonium nitrate N fertilization and water additions in the chamber microplot study were duplicated at the moisture levels of 30%, 60% and 90% water filled pore space in the soil cores, which were incubated for a week at 22 hr increments with and without acetylene. The results of the soil core incubation were applied to the microplots chamber data to obtain nitrification and denitrification pools of N₂O.