= Dry mass
<Dry mass> is the <mass> remaining after a specimen has been dried under a stated procedure. Removing <water> makes comparisons less sensitive to hydration, but the result remains operational: drying conditions can also remove volatile compounds or alter the material. A reproducible measurement specifies specimen preparation, drying conditions and the criterion for stopping.
For example, a rice-biomass protocol separates <leaves>, stems and reproductive structures, dries the components at $70\,{}^{\circ}\mathrm C$, and checks for constant <mass>. Its stopping criterion is no change in the measured <mass> over 24 hours.<Procedure for determining aboveground biomass and nitrogen content in ORYZA by IRRI>[Procedure, drying and final oven-dry weighing]{ref} This is a protocol for those samples, rather than a temperature prescribed for every biological material.
For a synthetic calculation, a specimen has fresh <mass> 12 g and <dry mass> 3 g. The loss on drying is 9 g, or $9/12=75\%$ of fresh <mass>. The same loss is $9/3=300\%$ of <dry mass>. Both ratios describe the stipulated measurements, but use different denominators. Interpreting the loss specifically as <water> requires the assumption that other losses are negligible. <Dry mass> also includes retained inorganic material; it is not synonymous with the <mass> of organic nutrients.
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