ARS | Publication request: Ammonia Losses From Surface-Applied Urea-Based Nitrogen Fertilizers

Submitted to: Cotton Research and Extension Report
Publication Type: Experiment Station
Publication Acceptance Date: February 15, 2008
Publication Date: March 15, 2008
Citation: Ducamp, F., Mitchell, C.C., Arriaga, F.J., Balkcom, K.S. 2008. Ammonia Losses From Surface-Applied Urea-Based Nitrogen Fertilizers. Cotton Research and Extension Report. No. 32 p. 39-40.

Interpretive Summary: Nitrogen fertilizer losses due to volatilization can greatly reduce the nitrogen efficiency and availability to crops of urea-based fertilizers. These losses are greater during summer months because of the high temperatures and drier soil conditions. Losses can be as high as half of the total nitrogen applied, depending on the soil, weather and fertilizer type. Nitrogen stabilizers may reduce volatilization losses enabling the use of less expensive urea fertilizers. During the unusually hot and dry summer of 2007, the effect of Agrotain® and calcium chloride on nitrogen volatilization as ammonia from urea and the liquid urea-ammonium nitrate (UAN) fertilizers were studied. Atmospheric ammonia was measured at 0, 1, 2, 3, 5, 8 and 17 days after fertilizer application, in two different field conditions, soil covered with rye (Secale cereale L.) residue and bare soil. The use of Agrotain® mixed with urea significantly reduced the rate of ammonia volatilization, accumulated ammonia losses and the fraction of nitrogen volatilized from the fertilizer, when compared to urea alone. The amount of ammonia lost was not reduced with the use of Agrotain® or calcium chloride when UAN was used as a nitrogen fertilizer. Use of materials that can inhibit nitrogen fertilizer losses can help farmers reduce production costs and reduce the environmental impact of nitrogen fertilization by minimizing losses to water bodies and the atmosphere.

Technical Abstract: Ammonia volatilization from surface applied urea-based sources of nitrogen (N) may reduce the efficiency of N fertilizers and the availability of N to crops. Nitrogen losses through ammonia volatilization are greater during summer months because N fertilizers are applied in conditions of high temperatures and rapid soil drying. It has been reported that N losses through ammonia volatilization can be 50 % of total N applied depending on the source of N used and soil and environmental factors. Nitrogen stabilizers may reduce volatilization losses enabling the use of less expensive urea fertilizers. During the unusually hot and dry summer of 2007, we compared the effect of Agrotain® and Calcium chloride on the ammonia volatilization from urea and UAN fertilizers (applied at a rate of 134 kg N ha-1). Atmospheric ammonia was measured at 0, 1, 2, 3, 5, 8 and 17 days after fertilizer application, in two different field conditions, 1) soil covered with rye (Secale cereale L.) residue and (2) bare soil. Treatments for each situation were: 1) Control (no N added), 2) urea, 3) urea+Agrotain®, 4) UAN, 5) UAN+Agrotain® and 6) UAN+ CaCl2. In both field conditions, the use of Agrotain® mixed with urea significantly (P=0.05) reduced the rate of ammonia volatilization, accumulated ammonia losses and the fraction of N volatilized from the fertilizer, when compared to urea alone. UAN+Agrotain® and UAN+CaCl2 treatments did not reduce accumulated ammonia losses and the fraction of N volatilized from the fertilizer, when compared to UAN alone.