GLBRC082: Plant Biomass Carbon and Nitrogen Analysis- GLBRC BCSE & Scale-Up Sites

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In use from 2008-01-01

Protocol

• Plant samples are collected twice a year from all the GLBRC ten treatments to determine total carbon and nitrogen content of plant tissues. These are collected at peak biomass stage and at final harvest time.
• The purpose of the sampling is to estimate total carbon and nitrogen removed in biomass
ANPP samples: annuals (G1-G4) – measure CN on the grain, stover, and weeds separately
ANPP samples G5, G6, M3, and L2: measure CN on the target species (switchgrass or Miscanthus) and on a composited sample of all other species
ANPP samples G7, G9, G10, M2, and L3: measure CN on the 3 most dominant species in each plot and on a composited sample of all other species
• Harvest samples in annuals: measure CN on grain from each main and microplot, also on corn stover
• Harvest samples in perennial plots – one composite sample is taken from each main and microplot
• Cover crop samples – measure CN on rye, Austrian pea, and a composited sample of all other species
• Samples are dried at 60oC for 48 h and dried plant material is ground through a 1mm screen using a Christy-Turner 8” Lab mill.
• Triplicate subsamples (5.0 mg) of the sample are weighed with an electronic microbalance, packed into tin containers, and combusted at 1050oC in an O2 -enriched atmosphere.
• Combustion gases are analyzed for C and N with a thermal conductivity detector after separation on a Porapak Q column.

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