Interaction Effects of Nitrogen Fertilizer Sources and Soil Salinity on Ammonia Volatilization

Leaching and ammonia volatilization are known as the main pathways of nitrogen loss as well as the cause of low nitrogen use efficiency. The present study aimed to study the interaction of five nitrogen fertilizer sources (ammonium sulfate, ammonium nitrate, urea, sulfur coated urea and potassium nitrate) and three soil salinity levels (ECe = 2, 8, and 12 dS/m) on daily as well as cumulative ammonia volatilization. The results showed that salinity and nitrogen fertilizer sources had significant effect on cumulative and daily ammonia volatilization rate. At soil salinity of 2 dS/m, nearly 51%, 44%, 45%, 6% and 0.01% of ammonium sulfate, ammonium nitrate, urea, sulfur coated urea, and potassium nitrate were lost through ammonia volatilization, respectively. These values at soil salinity level of 12 dS/m significantly increased to 73.7%, 54%, 57%, 8%, and 0.01% for ammonium sulfate, ammonium nitrate, urea, sulfur coated urea and potassium nitrate, respectively. In general, the results showed that potassium nitrate had the minimum ammonia loss through volatilization and was followed by sulfur coated urea, urea, ammonium nitrate, and ammonium sulfate, respectively. Regarding the highest nitrogen uptake efficiency and minimum nitrogen loss, potassium nitrate is recommended as the most efficient source of nitrogen fertilizer.