Soil and Water Conservation Laboratory

Soil and Water Conservation Laboratory Standard Operating Procedure

Plant Tissue Analysis

Reference Method: Total Nitrogen (TN) and Total Carbon (TC) concentration (%) of the tissue is determined via combustion with a LECO CN2000 (LECO, Warriewood, Australia) analyzer (Isaac and Johnson, 1985) at the University of Hawai‘i Mānoa Agriculture Diagnostic Service Center (ADSC) Laboratory. .

Purpose To determine the total nitrogen (TN) and carbon (TC) elemental content of plants or of certain plant parts.

Materials and Equipment  Newspaper or paper bags  Drying oven, controlled at a fixed temperature of 40 ± 5o C  Ball mill and grinder  Funnel of clean paper sheets (folded in half)  Plastic scintillation vials with caps  Chem-wipes  Appropriate lab attire  Heat resistant gloves

Preliminary preparation: Drying and grinding using a ball mill. - Plant tissue analysis is performed on dried plant tissue that has been processed in a laboratory. - Plant tissue samples should be collected from the correct plant part at the appropriate stage of development. - Do not include senesced/diseased leaves in the sample unless your intent is to determine the nutrient status of these tissues. - Procedures: 1. Rinse plant samples with distilled water to remove any salt, sediment, or dust particles and blot dry. 2. To prepare for drying, place samples in labeled paper material (between newspaper sheets or in paper bags). 3. Dry samples to a constant weight in a forced draft oven at 40°C until a constant mass is achieved, generally 48-72 hours but will depend on lignin content. 4. Remove dried material from oven with heat resistant gloves and record the weight of the samples (g). 5. Grind dried samples by filling grinder container with sample, ensuring ball is inside and without stuffing material too tightly, close container lid tightly. 6. Secure grinder container into mill and allow to run for about 10 minutes or until sample is milled into a homogenous powder. 7. Funnel ground sample into appropriate scintillation container (be sure to label cap!). This can be done using a funnel or a folded piece of clean paper by pouring sample onto paper then pouring carefully into container. 8. Clean grinder (and funnel) thoroughly between uses using chem-wipes and distilled water.

Calculations

Biomass (g/m2): Obtained through a deconstructive harvest per area (m2) or per plant basis.

Accumulation rate (g/m2/yr-1):

DW = Dry weight

Example Accumulation Rate Calculation:

Cladium jamaicense at 7 months had 1.42% TN concentration in its tissue sample with a dry weight biomass of 2991.694 g/m2.

Isaac, Robert A. and William C. Johnson. 1985. Elemental Analysis of Plant Tissue by Plasma Emission Spectroscopy: Collaboration Study. Journal of the Association of Official Analytical Chemists (JAOAC); Vol. 68, No. 3.