Synthesis of slow-release nano-fertilizer from plasma nitrogen and banana peel cellulose

The increasing demand for affordable nitrogen fertilizers could promote the use of low-cost non-thermal plasma nitrogen (PN) harvesting from the atmosphere and from water sources. Similar to urea, PN faces challenges in the controlled release of nitrogen. In this study, PN was electrocatalyzed to form an N-rich ammonium chloride salt, which was graft-polymerized with banana peel cellulose nanofibrils (BPCNF) to develop a nano-plasma N (NPN) compound for slow nitrogen release. For comparison, urea was also encapsulated in BPCNF to produce nano-urea (NU). To evaluate agronomic performance, a screenhouse experiment was conducted to assess the fertilizing effect of NPN on maize. Structural and chemical characterizations of NPN and NU provided evidence for semi-interpenetrating polymer networks (semi-IPNs) and component interactions that help control moisture diffusion, thereby improving nutrient retention in the soil. The produced nano-fertilizers demonstrated excellent water absorption, with swelling values of 235% for NPN and 226% for NU. They also enhanced the soil's water retention capacity by extending the time to reach 50% field capacity by two days from nine days. These responses enable efficient water use and reduce irrigation frequency. Moreover, the nano-fertilizers exhibited controlled nitrogen release, with 93% and 76.2% released for NU and NPN, respectively, after 29 days, indicating the need to meet European standards. Similar to NU, NPN application in maize increased growth, biomass, and grain yield by up to 37, 36, and 30%, compared to urea and PN. The Nitrogen Recovery Efficiency increased up to 60% and 83% for NU and NPN, respectively, improving the economic yield per fertilizer nutrient. These benefits combined with an eco-friendly production process that leverages plasma and nanotechnology, strengthen the potential of NPN to address fertilizer challenges in sustainable agriculture.