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Abstract
Nitrate is the primary nitrogen source for crops but poses environmental risks through leaching and nitrous oxide emissions, particularly in manured agricultural systems. Long‑term manure application can increase soil pools of recalcitrant organic nitrogen that mineralize slowly and contribute nitrate during periods of low crop uptake. This study developed the RONDIMS model to estimate long‑term accumulation and mineralization of recalcitrant organic nitrogen, predicting substantial cool‑season nitrate production. Field measurements using ion exchange resin/soil cores in Oregon’s Willamette Valley confirmed significant cool‑season mineralization. Method comparisons showed disturbed cores reduced variability but occasionally increased mineralization, highlighting trade‑offs in measurement approaches.