Nitrogen budgets in US soybean-based agroecosystems

Achieving neutral nitrogen (N) budgets is critical for soil health and sustainable agriculture. Thus, 31 studies were conducted for soybeans (Glycine max L.) throughout the United States, determining N inputs, biological N2 fixation via δ15N natural abundance method, and N outputs, seed N removal. On average, 53% of the N demand was met through N2 fixation, while the requirement of 62% indicates a significant shortfall for achieving neutral N budgets.