The document discusses Low External Input Sustainable Agriculture (LEISA), a system that optimizes local resources and minimizes external inputs. It focuses on combining various agroecosystem components like soil, climate, water and humans. External inputs are only used when needed to supplement the agroecosystem and increase sustainability. While it does not maximize short-term productivity, it aims to be stable and adequate in the long-term. It is built from renewable resources from the local environment and allows some external inputs to balance productivity while maintaining sustainability.