High resolution HPLC-MS confirms overestimation of urea in soil by the diacetyl monoxime (DAM) colorimetric method

Urea represents a common form of organic nitrogen (N) which is added to agricultural soils in large quantities in both cropping (e.g. fertiliser) and livestock (e.g. urine) systems. In addition, there is a small, dynamic ambient pool of urea in soil associated with metabolic functioning in the microbial community. The diacetyl monoxime (DAM) colorimetric method is routinely used to quantify urea in soil, however, it lacks specificity due to the...