Strong linkage between nutrient-cycling functional gene diversity and ecosystem multifunctionality during winter...

Microorganisms play important roles in element transformation and display distinct compositional changes during composting. However, little is known about the linkage between nutrient-cycling functional gene diversity and compost ecosystem multifunctionality (EMF). This study performed winter composting with pig manure and fallen leaves and evaluated the distribution patterns and ecological roles of multiple functional genes involved in nutrient cycles. Physicochemical properties and enzyme activities presented large fluctuations during composting. Absolute abundance, composition, and diversity of functional genes participating in carbon, nitrogen, phosphorus, and sulfur cycles presented distinct dynamic changes. Stronger linkage was found between enzyme activities and temperature than other physicochemical factors, whereas total nitrogen rather than other physicochemical factors displayed closer linkage with functional gene composition and diversity. EMF targeting key nutrient (i.e., carbon, nitrogen, phosphorus, and sulfur) cycles was significantly positively correlated with temperature and notably negatively correlated with functional gene diversity. Enzyme activities rather than functional gene diversity showed a greater potential effect on phosphorus availability. Consequently, the available phosphorus (AP) content increased from initial 0.50 g/kg to final 1.43 g/kg. To our knowledge, this is the first study that deciphered ecological roles of nutrient-cycling functional gene diversity during composting, and the final compost can serve as a potential phosphorus fertilizer.