Romain Cools of the potato growers' union Belgapom presented it as a matter of survival, as a major export sector fears ruin in the coronavirus crisis.
About 750,000 tonnes of potatoes are piled up in Belgian warehouses, as the lockdown has sent orders plummeting.
"Let's all eat chips twice a week, instead of just once," Mr Cools urged.
Since mid-March, restaurants in Belgium and many other markets for potato growers have closed. The cancellation of Belgium's many spring and summer festivals has added to their woes.
