『Abstract
　We modeled the expected range of seasonal and annual N2O flux from temperate, grain agroecosystems using Monte Carlo sampling of N2O flux field observations. This analysis is complementary to mechanistic biogeochemical model outcomes and provides an alternative method of estimating N2O flux. Our analysis produced a range of annual N2O gas flux estimates with mean values overlapping with results from an intermodel comparison of mechanistic models. Mean seasonal N2O flux was 1-4％ of available N, while median seasonal N2O flux was less than 2％ of available N across corn, soybean, wheat, ryegrass, legume, and bare fallow systems. The 25th-75th percentile values for simulated average annualized N2O flux rates ranged from 1 to 12.2 kg N ha^-1 in the conventional system, from 1.3 to 8.8 kg N ha^-1 in the cover crop rotation, and from 0.8 to 9.3 kg N ha^-1 in the legume rotation. Although these modeling techniques lack the seasonal resolution of mechanistic models, model outcomes are based on measured field observations. Given the large variation in seasonal N gas flux predictions resulting from the application of mechanistic simulation models, this data-derived approach is a complimentary benchmark for assessing the impact of agricultural policy on greenhouse gas emissions.

Keywords: Nitrogen; Nitrous oxide; N trace gas; Corn Belt』

Introduction
Methods
　Agroecosystem studied
　Data sources and summary statistics
　Model framework
　N2O flux calculations
　Model implementation
Results and discussion
　N2O flux trends
　Monte Carlo simulation
　Forecasting N2O flux
Conclusions
Acknowledgments
References