Effect of application methods on ammonia volatilization from soils in a controlled environment

Abstract

The objective of this investigation was to compare different application methods whereby ammonia losses from nitrogen fertilizers can be limited when applied to alkaline soils. Three application methods were simulated, namely broadcasting, ploughing under and band placement. Five nitrogen fertilizers, namely (NH₄)₂SO₄, LAN, urea, MAP and DAP were applied at a rate of 120 kg N ha^-1 to five soils which ranged in clay content between 7,6 and 49,9%. The pH(H₂O) of the soils was adjusted to approximately 8,8. After a contact period of 14 days significant losses of NH₃ occurred when the fertilizers were broadcast, compared with simulated ploughing under and the band placement. The depth of application which is sufficient to limit ammonia loss in a specific case, depends on the concentration of NH₃ present in the soil solution and the diffusion of NH₃ to the soil surface. Knowing the properties of the fertilizers and of the soil an appropriate combination of fertilizer and application method may be chosen to limit losses of N, especially volatilization of NH₃.

Keywords:

• Alkaline soils
• ammonia volatilization
• application methods
• nitrogenous fertilizers