BOX 1-4 Contemporary Remote Sensing Technology
The technologies that can contribute to site-specific crop management—remote sensing, the global positioning system, yield monitors and mapping, geographic information systems, variable-rate application technology, computers, and electronic communication—are currently converging. Rapid growth in precision agriculture is stimulating renewed interest in developing remote sensing, especially from satellites, for crop management applications. Imagery acquired from continuously orbiting satellites operated by commercial companies will enhance the possible applications and utility of remote sensing, and farmers will not have to contend with the challenges of collecting photographs. Fritz (1996) suggests that despite high development costs, satellite systems will be cost competitive with aerial imaging systems. He indicates that per unit of coverage, satellite imagery may be only one-half the cost of aerial imaging.
The changes in U.S. policy resulting from the 1992 Land Remote Sensing Policy Act and the 1994 Presidential Directive on LANDSAT Remote Sensing Strategy specifically encourage commercial system development and operation and have led to several companies developing plans to launch satellite systems in 1997 through 1999. The new imaging satellites will acquire panchromatic (1- to 3-meter spatial resolution) and multispectral (4- to 15-meter resolution) imagery over swaths of 6 to 30 kilometers. At least two companies are targeting agriculture and precision farming as either the primary application or as a major target of their planned marketing and sales efforts.
Remote sensing products could play an important role in site-specific crop management, and there is also excellent market potential for the acquisition, processing, and delivery of remote sensing information. Perhaps no other application of remote sensing requires data so often over such large geographic areas. However, infrastructure to meet this requirement is not currently in place. Widespread application and successful adoption of remote sensing data products are not likely until such an infrastructure is developed; cadres of people who understand the relationships between crop-soil properties and remote sensing are especially important. Similarly, more information and study on integration and use of spatial information in crop management is needed as well as opportunities for training in the use of spatial information. It will be very important for systems and data products to be based on crop producer needs, and for provisions to be made for farmers and others to develop an understanding of remote sensing.