Urea for CO2 Fertilization.

Carbon (C) is an essential element for crop growth, with carbon dioxide (CO₂) in the atmosphere as the C source for photosynthesis. Enrichment of CO₂ concentration increases photosynthesis, leading to improved plant growth and yield. However, CO₂ is also responsible for 82% of greenhouse gases (GHGs). Hydrolysis of urea results in CO₂ emission. Globally, about 136 million tons of urea is consumed annually in agriculture, resulting in 100 million tons of CO₂ emission as a byproduct of urea hydrolysis. This could translate to CO₂-enrichment and improved crop growth or conversely to negative impact on the environment as GHG. The presentation highlights nitrogen management practices and modified urea products that could control urea hydrolysis and/or CO₂ diffusion, and thereby increase the utilization of CO₂ for improved crop growth and reduced GHG emission. CO₂ emissions from urea, urea deep placement (UDP), urea with urease inhibitor (Agrotain), control-release polymer coated urea (ESN), and ammonium sulfate (check) are compared under upland and flooded conditions.  The use of nano-sized carbonates as foliar application to increase CO₂-enrichment is also discussed.