Cuban zeolite as ammonium carrier in urea-based fertilizer pellets: Photoacoustic-based sensor for monitoring N-ammonia losses by volatilization in aqueous solutions

Abstract The loss of mineral nitrogen by ammonia volatilization is one of the main drawbacks in modern agriculture. This work proposes the use of a quantum cascade laser-based photoacoustic sensor to continuously monitor ammonia emission rates from fertilizer pellets in aqueous solutions. Pellets were obtained mixing different contents (2.5, 20 and 40 wt.%) of Cuban zeolite with urea. The pH of aqueous solutions was also monitored and its maximum value was 9.5 for pellets with 40 wt.% of zeolite. Urease obtained from soybean seed extract was added to the solution. Ammonia emission rates were enhanced due to the catalytic action of urease on the urea hydrolysis. The use of Cuban zeolite (40 wt.%) reduced the ammonia volatilization from the solutions by approximately 33%. The results give us important clues to reach a better understanding of the kinetics of ammonia release from pellets and the use of zeolite in agriculture as an innovative material to control the retention of mineral nitrogen into soils.