Effect of soil salinity on ammonia emission

The use of fertilizers in agriculture is identified as a significant source of ammonia emissions (NH3). These emissions not only lead to yield loss but also contribute to the indirect emissions of other greenhouse gases. NH3 emissions from the use of nitrogen fertilizers occur through volatilization from the soil surface, controlled by the concentration gradient and resistance to NH3 transport between the atmosphere and soil surface. Soil pH, moisture, and the state of nitrification are key factors that control the rate of volatilization. In this context, the interaction between fertilizer and soil type may play a crucial role in controlling emission rates. In our study, two different soil types, non-saline soil (1.15 dS m-1) and saline soil (35.80 dS m-1), were compared along with three different fertilizer types (ammonium sulfate, urea, and biogas waste). NH3 losses were measured over 32 days in a robotic continuous flow incubation system. The soil samples placed in incubation chambers were sealed airtight after adjusting their moisture content to 75% of water-holding capacity. In the experiment, nitrogen fertilizer was not applied to one set of soil samples (control), while 15 kg N da-1 of urea, ammonium sulfate, and biogas were applied to the others. Nitrogen fertilizer applications in both soil types resulted in NH3 emissions. When comparing soil types, particularly in saline soils, applications of ammonium sulfate and biogas waste led to higher NH3 emissions compared to non-saline soils. The salinity of the soil is known to significantly influence the nitrification process, which is the formation of nitrate in the soil. This study concludes that the relationship between soil salinity and NH3 emissions is particularly dependent on the applied fertilizer form.