Constraining nitrogen cycling and mass balances with natural abundance nitrogen isotopes in a tile-drained corn-soybean rotation

Assessing nitrogen (N) mass balance and use efficiency is essential for tracking progress toward sustainable agriculture. However, the links between N surpluses or deficits, crop productivity, and environmental N losses remain poorly understood, particularly in rotational cropping systems. In this study, we combined natural abundance N isotope measurements across soil, water, and crop N pools with laboratory denitrification experiments to quantify N source-sink strengths in a tile-drained corn-s