Plant Analysis Methods

Parameter

Method

Method Description

Dry matter

Gravimetric

A known weight of sample is placed in an oven at a temperature of 103 degrees Celsius for a given length of time.

After cooling it is re-weighed and the loss of weight is the moisture

content of the sample. Dry matter is the calculated from the lost moisture.

Plant Total Nitrogen

Combustion

The Dumas combustion method is an absolute method for the determination of the total Nitrogen content. The procedure entails heating a sample of known mass to between 800 and 900 degrees Celsius in the presence of oxygen. Via subsequent oxidation and reduction tubes, nitrogen is quantitatively converted to N2. Other volatile combustion products are either trapped or separated. A

Thermal Conductivity Detector measures Nitrogen gas. Results are given as %

Plant Cations – Ca, Mg, K, Na, Mn, Mo, Fe, Cu, B, Zn, P, S

Atomic Emission spectrometry ( ICP- OES)

Microwave Digestion :-Nitric Acid & Hydrochloric Acid

A representative sample previously dried at 60 degrees Celsius to constant weight is extracted and/or dissolved in concentrated nitric acid- Hydrochloric acid using microwave energy on the laboratory microwave unit. The sample and acids are placed in a fluorocarbon polymer (PFA or TFM) microwave vessel or vessel liner. The vessel is sealed and

heated in the microwave unit for a specified period of time. After cooling, the vessel contents are diluted to volume and analyzed using ICP-OES.