English to Spanish Science Environment & Ecology Sustainable agriculture

Inicialmente pensé en modelo de dos vías, pero no me convence plenamente.
El contexto es el siguiente:
...a proposal was developed (which needs considerable further elaboration) based on a ‘two-pillar’ model or approach. The first pillar consists of a certification system of responsible agricultural production. The second pillar is a much wider programme aimed at suporting producers to improve social, environmental and economic performance.