Large scale adoption of nitrogen (N) management practices, including the 4Rs, could lead to beneficial environmental and economic outcomes, but only if they improve agricultural profit or are driven by policy and legislation. This study uses a spatial economic maximization and environmental simulation model to examine the economic and environmental tradeoffs of adopting three different 4R practices, specifically N rate reduction, timing (sidedress versus at-planting) and placement methods (broadcast versus injection) in Ontario corn production, under alternative annual weather conditions. The study shows that the use of optimized agronomic, based on meeting crop N requirements specific to each fertilizer management practice, rather than historic, N application increases annual average Ontario-wide farm profit from $124 million to $173 million (39.5%), decreases N application from 122 to 97 kt (20.5%), decreases nitrous oxide (N₂O) emissions from 3.4 to 2.4 kt (29.4%), decreases ammonia (NH₃) volatilization from 12.4 to 1.2 kt (90.3%) and decreases nitrate (NO₃⁻) leaching from 47 to 13 kt (72.3%), over 30-years of weather data. Injection and sidedress appear to be more N use efficient than broadcast, with sidedress becoming increasingly important as N prices and constraints increase. N₂O emissions appear to be more difficult to mitigate compared to NH₃ emissions and NO₃⁻ leaching. Regarding the 4Rs, right placement and right timing play a role under specific spatial conditions, while right rate appears to be the most effective means to mitigate the environmental impacts of corn N application and may be mutually beneficial to farmers and society.

大规模采用氮管理实践（包括4R）可能会带来有益的环境和经济成果，但前提是要提高农业利润或受政策和法规的推动。这项研究使用空间经济最大化和环境模拟模型来检验在安大略省玉米生产中采用三种不同的4R做法的经济和环境折衷，特别是氮肥减少，施肥时间（种植与播种）和播种方法（播种与注入） ，在其他年度天气条件下。该研究表明，基于满足每种肥料管理实践特定的作物N需求而不是历史的氮肥施用，优化农艺措施的使用将安大略省范围内的年平均农场利润从1.24亿加元增加到1.73亿加元（39。₂ O）从3.4排放2.4克拉（29.4％），减小氨（NH ₃）挥发从12.4到1.2克拉（90.3％），并降低硝酸盐（NO ₃ ^- ）浸出从47到13克拉（72.3％），经30年的天气数据。注入和肥料比氮肥的利用率更高，随着氮素价格和限制因素的增加，肥料变得越来越重要。与NH ₃排放和NO _3-相比，N ₂ O排放似乎更难缓解^。浸出。关于4Rs，正确的放置和正确的时机在特定的空间条件下发挥作用，而正确的比例似乎是减轻玉米氮肥施用对环境影响的最有效手段，并且可能对农民和社会互利。