Background Variability in crop growth over a field can seriously reduce a farmer's income. Factors that are out of a farmer's control, such as soil type and weather conditions, can accentuate growth variability. The use of remote sensing as part of a multi-layered information system can help to identify the characteristics of those heterogeneous zones and enable farmers to adjust their management practices to improve yield. A Montana farmer was concerned about a large area of bare, unproductive soil in the middle of an irrigated alfalfa field. He was interested in using remote sensing to determine how he could make the area more productive.

 Use of Data The farmer used imagery from both Landsat ETM+ and a KODAK 420 color infrared camera (CIR). The advantage of the CIR system is that it gives farmers more flexibility in the date and timing of data acquisition. The imagery, coupled with soil conductivity information from the VERIS system, soil maps, and field scouting/soil testing, enabled the farmer to identify characteristics of the unproductive area of the field (Figure 1). He found that the soil in the middle of the field had a high salt content, a characteristic unsuitable for alfalfa growth.

 Economic and Environmental Benefits Based on the results of his analysis, the farmer decided to plant a different crop in the affected area. He sowed a more salt tolerant species, which enabled him to obtain greater productivity and therefore made his field more profitable.

In addition to the economic benefits, planting the alternative species was environmentally sound. The increased vegetative cover reduced the amount of bare soil, thereby reducing wind and water erosion. Landsat imagery and aerial color infra-red images, combined with the other data, played an important role in the successful management decision.