5.0   Rationale and Significance

Economic and environmental pressures are causing the agricultural production sector to seek more competitive ways of producing food and fiber products.  With the development of the Global Positioning System (GPS) and variable-rate application technology (VRT), today's agriculture is entering a new era – the era of precision agriculture. The combination of these technologies has the potential to improve productivity and profitability while conserving and protecting our natural resource base.  We are now able to focus attention to managing soils and inputs to crop production at a much finer resolution (e.g. 30-meter grid as opposed to 20-hectare units).  Traditional farming practices treat fields as independent units and assumes homogeneous agronomic factors.  The reality, especially in upland regions, is that many fields exhibit a wide range of variability that may be a function of multiple soil series or mapping units, and past management practices.  Further, such variability may impact water quality if these fields are managed on a field-average basis, as current practices dictate.

Site-specific management, or precision agriculture, is now possible with the development of technologies such as the GPS and Geographic Information Systems (GIS).  GPS enables equipment operators to quickly obtain positioning information while a GIS is essentially a database for managing these geographic data.  Nutrient management, fields are grid-sampled for soil fertility, usually on a one to three acre basis.  Grain combines equipped with yield monitors and GPS receivers log instantaneous yield and position data.  Fertility and yield maps are then generated by combining these data with a GIS package.  Utilizing both historical yields and known fertility levels, crop consultants can generate “site-specific” application recommendations in the form of rate maps.  Site-specific fertilizer application services are currently available from farm suppliers in some regions of Kentucky.  GIS and GPS technologies have been used to manage nutrients through the application of inorganic fertilizers (Robert et al., 1991; Mulla, 1991; Carr et al., 1991; Li et al., 1992; Neuhaus and Searcy, 1993; and Birrell et al., 1993).