Carbon and Nitrogen Dynamics in Upland Soils

Upland soils constitute the majority of soils in farm and ranch areas throughout the world. They also dominate forested areas. Because these soils tend to be better aerated than wetland soils, oxygen presence plays a key role in the process dynamics and management responses of these systems, and generally promotes higher decomposition rates of organic materials compared to wetland soils. Periodic wet and dry cycles on a seasonal or more frequent basis cause temporary shifts in oxygen availability that in turn affect process rates and directions. The landscape position of upland soils promotes drainage and movement of nutrients and soil particles to lower lying areas, and aspect exposure can have significant effects on temperature and water retention regimes. Location of the soils on the Earth relative to latitude and elevation also plays an important role in the accumulation of soil organic matter (SOM) and associated C/N dynamics (Povirk et al., 2000).