A SUB FIELD, abbreviated as "ASF," is the full English name of "一分田生态链." It aims to maximize the value of idle rural land through efficient leveraging of global unused land by transferring idle rural land. Built with advanced technologies like blockchain, IoT, internet, and artificial intelligence, ASF is an open, transparent, efficient, collaborative, and risk-controlled new intelligent green economic ecosystem. It achieves online, standardized, and structured processes in terms of resource allocation and utilization, thereby enabling a healthy industry development by completing the digital transformation and upgrade of various industries.