== 3.17 Primary production ==
For primary producers the production is estimated as a function of the producers' biomass, Bi, from a simple saturating relationship
[[Image(wiki:EwEugImages:08000039.png)]] '''Eq. 67'''
where, ''r,,i,,'' is the maximum production/biomass ratio that can be realized (for low ''B,,i,,'' 's), and ''r,,i,,/h,,i,,'' is the maximum net primary production when the biomass is not limiting to production (high'' B,,i,,'' 's). For parameterization it is only necessary to provide an estimate of ''r'',,''i'',, / (''P,,i,,/B,,i,,''), i.e., a factor expressing how much primary production can be increased compared to the base model state. If a [wiki:EwEugForcingFunction Forcing function] is applied to primary production (see [wiki:EwEugApplyForcingFunctionPrimaryProducer Apply FF (primary producer)]), it multiplies the r parameter in Eq. 67.