Namakana osnovna površina je enaka povprečni površini, namakani od leta 1989 do 1991 glede na žetev vključno s povečanjem pridelka iz člena 3(1), četrti pododstavek, zadnji stavek Uredbe (EGS) št. 1765/92. Vendar se namakana osnovna površina na Portugalskem postopoma povečuje največ do 60.000 ha za tiste površine, za katere je bilo ugotovljeno, da so se naložbe v namakanje začele po 1. avgustu 1992. Ta porast se lahko v celoti ali deloma doda namakani osnovni površini za koruzo iz člena 3(2).
The irrigated base area shall be equal to the average area irrigated from 1989 to 1991 with a view to harvesting arable crops including the increases made pursuant to Article 3(1), fourth subparagraph, last sentence of Regulation (EEC) No 1765/92. However, the irrigated base area in Portugal shall be progressively increased by up to 60 000 ha, for those areas where it has been established that investment in irrigation began after 1 August 1992. This increase may be added partially or totally to the irrigated maize base area as referred to in Article 3(2).