Nitrogen transport processes in soil

There is a complex relationship between transport and transformations of nitrogen (N). Leaching losses of nitrate can be affected by transformations due to denitrification, and by the uptake of nitrate by growing plants. Similarly, leaching losses can be affected by the processes of adsorption and biological transformations. Leaching is also affected by volatilization depending on the formulation of N applied to the soil. This chapter focuses on the processes affecting losses of N to the environment by transport in water flowing through or across the soil. A variety of conceptual mechanisms are outlined in this chapter, along with the most recent methods for identifying which mechanisms occur. The most recent experimental methods for quantifying the rate and magnitude of N transport in soil are also reviewed. The chapter concludes by reviewing methods for assessing spatial variability in nitrate transport through soils.