Number 17/Life & ecology/Ecology
The Saturation Ratio
The quantity
The ratio of added to native nutrient supply at which the growth response to further addition halves.
01Why it matters
It converts fertilisation experiments into a transferable parameter, so results from one site can inform another without repeating the dose-response.
02Expected value
Between 0.5 and 2.0 for nitrogen in temperate systems; lower where phosphorus co-limits.
03How it would be measured
Dose-response curves from nutrient addition experiments, already numerous.
04What would refute it
No saturation across sites would make the parameter infinite and the concept useless.