The use of remote sensing for precision agriculture applications is very popular and a popular use is the characterization of nitrogen (N) conditions. N is one of the most important fertilizer elements for crop production, and is an essential element for crop growth, development, and yield formulation. Nitrogen content deœciency will bring a series of changes to crop leaves, such as color, thickness, water content, form, and structure. A lack of nitrogen will directly affect the composition of amino acid, protein, nucleic acid, and other materials, which will lead to the reduction of crops photosynthesis capacity and the œnal yields. Therefore, N management is a very important management measure in agriculture produce for obtaining high yields and good quality. At the same time, overapplication of nitrogen will pollute underground water and also get into streams. To overcome this and other similar problems, precision agriculture (also referred to as precision farming or sitespeciœc farming) has been put forward. Precision N management is a key content of precision agriculture, which reduces pollution of the water resources and yet results in sustained high yields over space and time.