Advances in Nitrogen Management for Water Quality

Nitrogen (N) is an essential nutrient for crops and other plants and is needed for many plant physiological functions. Nitrogen is critically important for global sustainability of food and has been a key to the success of the green revolution. Due to its importance as a crop nutrient, N fertilizer is of great importance for maximizing crop production. Crop uptake of N follows a sigmoid function with N uptake necessarily preceding above-ground dry matter while early season N requirements of the root system are met. For most agricultural cropping systems, production cannot be maximized without additional N inputs. However, N inputs can also have environmental impacts because of increased losses of N to the environment (Cowling et al. 2002; Galloway et al. 2003). Management of this dynamic nutrient is a key to lessening its potential impact on the environment. Though N management is complex in many aspects, there are basic principles that can be used to reduce N losses via leaching and/or atmospheric losses (Meisinger and Delgado 2002; Mosier et al. 2002).