KBS029: MCSE: Plant C, N, and P
Sampling Frequency: Annually
Total carbon and nitrogen content of plant materials from each plot is measured on vegetation collected for primary productivity sampling with the use of an automated CHN analyzer. After drying at 60 degrees C for 48 h, plant materials are ground to pass through a 0.4 mm mesh using a Wiley Mill and Tecator Impact Pulverizer*. Triplicate subsamples (5.0 mg) of the sample are weighed with an electronic microbalance, packed into tin containers, and combusted at 1050 degrees C in an O 2 -enriched atmosphere. Combustion gases are analyzed for C and N with a thermal conductivity detector after separation on a Porapak Q column. Standards compounds include cyclohexanone-2,4-dinitrophenylhydrazone (1990 and prior), acetanilide (1991 to 1997) and phenacetin (1997+).
*From 2009-1-1, a Christy Turner Lab Mill with a 1mm screen was used to grind plant material.