Abstract
Bio-based controlled-release fertilizers (BCFs) are gaining traction due to their biodegradability and environmental sustainability. However, current straw-based controlled-release fertilizers encounter significant challenges, including short nutrient release durations, high modification costs, and limited functionality. To address these challenges, we developed a cost-effective, high-performance functional BCF through the effective pretreatment and value-added utilization of rice straw. The use of instant catapult steam explosion for straw pretreatment effectively removed liquefaction-inhibiting substances, thereby enhancing cellulose accessibility. This method resulted in a 9% increase in straw liquefaction yield and a 13% improvement in hydroxyl value when compared to traditional pretreatment techniques. Lignin extracted was dual-purposed as a membrane shell modifier to reduce pores and as a soil P activator. This modification reduced membrane shell porosity, extending the nutrient controlled-release period from 56 days (unmodified BCF) to 70 days (lignin-modified Bio-based controlled-release fertilizers, LBCF). The soil with LBCF application exhibited steadily increasing inorganic N content and remained elevated for an extended period, while lignin released during membrane degradation activated soil P and resulted in Olsen-P content significantly higher than that of urea (U) and BCF treatments. In lettuce cultivation trials, LBCF outperformed BCF and U, increasing lettuce N and P content, with a growth-promoting effect ranked LBCF > BCF > U. This approach facilitates a scalable pathway for straw valorization and the advancement of environmentally sustainable BCFs in sustainable agricultural practices.