Ammonia volatilization and fate in soil nitrogen pools of 15N-labeled enhanced-efficiency fertilizers

• Grant number: 23/09872-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: October 01, 2023
• End date: March 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Eduardo Mariano
• Grantee: Pedro Henrique Escaranaro Brasil
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The usage of urea-based fertilizers and those treated with urease inhibitors or coated aiming to gradual N release has attracted increased interest. Determining losses due to ammonia volatilization and the allocation of 15N-fertilizer in soil pools (and their temporal variations) is key for understanding the patterns of N release and its cycling by the microorganisms. A laboratory experiment will be conducted for 60 d in a 5 × 8 factorial, with the levels of the first factor represented by 15N-labeled fertilizers [1) control (no N); 2) conventional urea; 3) urea treated with N-(n-butyl)thiophosphoric triamide (NBPT); 4) urea treated with NBPT + Duromide; and 5) polymer- and S-coated urea], whereas secondary factor levels will be sampling times [0.5 (12 h), 1, 2, 4, 8, 15, 30, and 60 d after N application]. Fertilizers will be characterized by scanning electron microscopy and X-ray microtomography. A semi-open chamber will be used for incubation and a trap containing H2SO4 will capture the evolved ammonia. At each sampling time, pH and electrical conductivity of the soil will be quantified. In addition, the size and 15N abundance of mineral (ammonium-N and nitrate-N), organic (extractable organic N, residual organic N, and microbial biomass N) and total N (total extractable N and total N) pools will also be measured. The results will be submitted to ANOVA and means separated by Tukey's test, with a 5% probability of error. We expect that the study unravels knowledge gaps regarding ammonia emissions and temporal N variation of the enhanced-efficiency fertilizers to improve nutrient use by plants.