A Practical Case Report on the Node Point of a Butterfly Model Circular Economy: Synthesis of a New Hybrid Mineral–Hydrothermal Fertilizer for Rice Cropping

Abstract

With the increased importance of a circular economy in the world, in this paper we present a practical “butterfly model” (proposed by the Ellen MacArthur Foundation) case report: to gain extra benefits in rice cropping through hybridizing green products of mineral waste and agricultural waste recycling. Hydrothermal biorefinery was used to turn spent agricultural biomass into a value-added biomass nutrient solution (BNS). BNS and sericite mineral waste were mixed and used as a new hybrid mineral–hydrothermal fertilizer for rice cropping. The most important extra benefit of this new hybrid mineral–hydrothermal fertilizer was that the empty grains could be reduced to 1–4 grains/spike (normally, it is 12–18 grains/spike), without significantly decreasing the panicle weight or spike saturation. This case report provides a new logic for circular design at the “node” point of a butterfly diagram.