For centuries, traditional agricultural systems have contributed to food and livelihood security throughout the world. Recognizing the ecological legacy in the traditional agricultural systems may help us develop novel sustainable agriculture. We examine how rice-fish coculture (RF), which has been designated a "globally important agricultural heritage system," has been maintained for over 1,200 y in south China. A field survey demonstrated that although rice yield and rice-yield stability are similar in RF and rice monoculture (RM), RF requires 68% less pesticide and 24% less chemical fertilizer than RM. A field experiment confirmed this result. We documented that a mutually beneficial relationship between rice and fish develops in RF: Fish reduce rice pests and rice favors fish by moderating the water environment. This positive relationship between rice and fish reduces the need for pesticides in RF. Our results also indicate a complementary use of nitrogen (N) between rice and fish in RF, resulting in low N fertilizer application and low N release into the environment. These findings provide unique insights into how positive interactions and complementary use of resource between species generate emergent ecosystem properties and how modern agricultural systems might be improved by exploiting synergies between species. G lobal food security is becoming an acute problem because of the increasing world population (1), the limitation of agricultural resources (e.g., land and water) (2), and the effects of global climate change on crop production (3, 4). World agriculture currently faces great challenges in producing sufficient food while minimizing the negative environmental effects of crop cultivation.In the past 50 y, crop yields have substantially increased, mainly resulting from the use of chemical fertilizers and pesticides, the development of new crop varieties, and the improvement in cultivation methods. The heavy application of chemical fertilizers and pesticides for long periods, however, negatively affects the environment, induces pest resistance to pesticides, and increases agricultural costs (5, 6). As a consequence, modern agriculture now requires "rethinking" (1, 7), and such rethinking should include reconsideration of traditional agricultural systems (8-10).For many centuries, traditional agricultural systems have contributed to food and livelihood security throughout the world (8). Because traditional agricultural systems have been created, shaped, and maintained by generations of farmers who used management practices that were matched to local conditions, and because these systems are based on diverse species and species interactions, traditional agricultural systems reflect a successful adaptation to different environments and are rich in biological diversity (8,11,12). The recognition of the ecological legacy of these traditional agricultural systems and the integration of these unique experiences into our future farm designs could help us to develop more sustainable agriculture. In fact, stud...

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The discovery of iron-based superconductors (FeSCs), with the highest transition temperature (Tc) up to 55 K, has attracted worldwide research efforts over the past ten years. So far, all these FeSCs structurally adopt FeSe-type layers with a square iron lattice and superconductivity can be generated by either chemical doping or external pressure. Herein, we report the observation of superconductivity in an iron-based honeycomb lattice via pressure-driven spin-crossover. Under compression, the layered FePX3 (X = S, Se) simultaneously undergo large in-plane lattice collapses, abrupt spin-crossovers, and insulator-metal transitions. Superconductivity emerges in FePSe3 along with the structural transition and vanishing of magnetic moment with a starting Tc ~ 2.5 K at 9.0 GPa and the maximum Tc ~ 5.5 K around 30 GPa. The discovery of superconductivity in iron-based honeycomb lattice provides a demonstration for the pursuit of transition-metal-based superconductors via pressure-driven spin-crossover.