Ash is the residue remaining after all the combustible material has been burned off (oxidized completely) (Pond et al., 1995). Dried, ground samples were weighed into pre-weighed crucibles. The samples were ignited in a preheated muffle furnace at 550-600°C for three hours. After that, the crucibles were placed in a desiccator for about one hour. The crucibles were re-weighed and the percentage of ash was determined.
To calculate the percentage of ash in a sample, the weight of the sample after ignition was divided by (the weight of the sample before drying, multiplied by the percentage of DM in the air dried sample) and multiplied by 100.