A century of subclover: Lessons for sustainable intensification from a historical review of innovations in subterranean clover seed production

With a growing population and changing climate, there is an urgent need to increase global agricultural yields, while minimizing environmental impacts and land use. A component of this "sustainable intensification" process is the shift from synthetic fertilizer to nitrogen-fixing legumes. Subterranean clover (Trifolium subterraneum L.) is the world's most widely grown annual pasture legume and in Australia its widespread adoption over the past century has led to increases in soil fertility and productivity, enabling greater animal production and crop yields. Subterranean clover is an unusual plant, burying its seed to protect it from grazing animals, which complicates efforts to harvest the seed from below the soil surface. The challenge of harvesting this seed has driven innovative farmers and inventors in Australia to develop specialized machinery and techniques, turning Australia into the largest subterranean clover seed producer in the world. In this chapter we review literature, patents, primary sources, personal interviews, and family histories to collate this story, deliver an integrated history of subterranean clover seed harvesting and make recommendations for the future of the industry. The history of this unique, farmer-led industry provides a number of lessons for the development of successful agricultural systems and the factors that influence agricultural innovation. We analyze these lessons from the past in order to provide insights for sustainable intensification in the future.