Soil Carbon and Nitrogen Dynamics In Organic Crop Production of the Northern High Plains Ecoregion, Wyoming and Nebraska.

With a growing interest in obtaining high premium price for organically certified wheat grain, more farmers in Northern High Plains are considering converting to dryland organic production. However, current organic dryland winter wheat-fallow system relies on intensive tillage for weed control which results in significant long-term soil carbon (C) and nitrogen (N) losses.  We hypothesize that transitioning from the no-till system to organic may provide better start for organic production in contrast to transitioning from the conventional system. Soils under no till system have higher soil organic matter and reduced or altered weed seed bank.  This can limit the frequency of intensive tillage operations needed to control weeds, improve winter wheat nitrogen use efficiency (NUE), and reduce greenhouse gas (GHG) emissions. To our knowledge, the information on GHG inventories from Northern High Plains is lacking. The overall objective of this study is to compare agroecosystem C and N budgets between existing conventional, no-till and organic systems and assess the effects of transitioning from conventional and no-till to organic production. To accomplish this goal, we established long-term research to monitor carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), soil N mineralization, plant residue decomposition, crop yield and weed species population from long-term conventional, no-till and organic winter wheat-fallow scenarios and from a series of organically-managed sites that were recently established within the existing conventional and no-tillage production systems. We will report the results from the first year of study.