Predicting Potential Soil Nitrogen Mineralization Using Pyrolysis-coupled FTIR
摘要
Soil nitrogen is a key component of plant nutrition, but our ability to predict organic nitrogen mineralization potential remains incomplete. Analytical pyrolysis is an emerging technology used to characterize soil organic matter and the thermal stability of soil carbon. We hypothesized that using pyrolysis to characterize soil nitrogen and measure soil nitrogen release would provide us with a novel method to estimate soil mineralizable nitrogen. A novel online pyrolysis coupled with gas-phase FTIR (Fourier-transform infrared spectroscopy) technology was designed to investigate the thermal stability of soil nitrogen. The soil samples were pyrolyzed at a ramped temperature from 25 to 850 °C at a heating rate of 10 K min− 1, and we followed the pyrogram for ammonia. The temperature at which 50% of the material underwent pyrolysis, referred to as T50, was determined to quantify the thermal stability of organic nitrogen. The T50 was then correlated with potentially mineralizable nitrogen at the end of a 12-week lab mineralization study. A strong negative correlation (R = -0.70, P < 0.01), at a heating rate of 10 K min− 1 was found, linking thermal degradation kinetics and nitrogen mineralization. This research offers a valuable foundation for optimizing pyrolysis applications in the context of understanding and predicting soil organic nitrogen mineralization.