Societal changes have inspired research into the development of integrated systems for waste treatment, nutrient recovery, and energy efficiency. Alternative "greener" processes for fertilizer production, such as green ammonia synthesis with energy systems approaches, recovery of fertilizer nutrients from nitrogenand phosphorus-containing wastes 364 ; more sustainable nutrient forms, such as nanomaterials , and use of microbial and chemical additives to formulations designed to improve the efficiency of nutrient use are also being developed and patented. Interest in sustainable fertilizer is increasing, particularly in China; publications peaked in 2017, fell, and rose, driven by Chinese patent publication. Journal publications focus on soil and other properties derived from or for fertilizer use, while patents focus on waste sources and types, processing methods, and use as soil amendments or in other roles.