Nitrogen dynamics as a function of soil types, compaction, and moisture

Abstract

The complex interactions between soil types, compaction, and moisture on nitrogen transformation processes, such as ammonia volatilization, ammonification, nitrification, and denitrification, were examined using a simulated columns study. Over the course of 30 days, two different soil types—loam and sandy loam—were subjected to three different compaction treatments (control, surface, and sub-surface compaction), and two different moisture treatments (dry and wet). Liquid urea ammonium nitrate (32-0-0) was used as nitrogen fertilizer at the rate of 200 kg N ha-1. Measurements were taken for important indicators of nitrogen transformations, such as residual concentrations of ammonium and nitrate, nitrate leaching, ammonia volatilization, and nitrous oxide emissions. The findings showed that compaction increased residual ammonium concentrations in deeper soil profiles and decreased nitrification rates in both soil types. Loam soil showed increased nitrate leaching due to higher rates of nitrification and residual nitrate concentrations. The interaction of compaction and moisture had the greatest impact on nitrous oxide emissions, with the highest emissions observed in control treatments during simulated dry weather. Higher ammonia volatilization was observed in moist sandy loam soil under control treatment. The results highlight the significance of taking soil texture, moisture, and compaction into account when implementing sustainable nitrogen management techniques in agriculture. Based on these findings, a number of recommendations are put forth for effective nitrogen management, including the avoidance of broadcast application in moist soil to reduce ammonia volatilization and improve nitrogen use efficiency, and split application to reduce potential nitrate leaching and nitrous oxide emissions from loam soil.