Precision agriculture has become a very common term. A subcomponent of precision agriculture is site-specific crop management (SSCM). SSCM centers around identifying variability within or across fields. Once the variability has been identified, the task turns to identifying ways to manage that variability. In a nutshell, SSCM deals with doing the right thing, at the right time, in the right way. There has been a flood of rapidly developing technologies (often very costly) that have confronted producers; the aim of these technologies has been to assist producers in managing the variability in their fields. The underlying goal for producers, however, is to use these technologies to increase the profitability and sustainability of their operations.

SSCM technologies have a history of generating a tremendous amount of data. Along with this mountain of data has come an avalanche of questions. University researchers, industry personnel, and private producers (among others) have been attempting to sort out specific answers to the multitude of questions that have surfaced regarding SSCM. But in all reality, there is a general lack of clear, concise answers to the many questions that have arisen from this technology. Clearly, there is a need for some unbiased, research-based data to aid in the answering of these questions.

Researchers at Iowa State University were offered and accepted a challenge to help Iowa soybean producers better understand the practicality, profitability, and sustainability of SSCM practices. In 1996, a 3-year project funded by the Iowa Soybean Promotion Board was initiated in producers' fields with the primary objective of using some of the new SSCM technologies to aid in identifying sources of variability that may be affecting soybean yields. As this project draws to a close, it is evident that additional research is needed to try and answer some of the more specific questions related to the practicality and profitability of certain SSCM technologies. Therefore, a second 3-year SSCM project funded by the Iowa Soybean Promotion Board will begin in the 1999 growing season.

The focus of this second project is to provide answers to the questions producers most frequently ask regarding SSCM; answers that can help producers better understand the variability in their fields and how to manage that variability in a profitable, yet sustainable manner. The research will be conducted on producers' farms using current SSCM production practices. Soybean and corn acres that have been mapped for yield trends and other specific characteristics will be used in the study. A team of researchers representing multiple disciplines related to SSCM will conduct this study. This team will be comprised of discipline coordinators from the departments of agronomy, plant pathology, economics, and agricultural and biosystems engineering, and USDA research scientists from the National Soil Tilth Laboratory.

Individual, as well as interrelated studies, will be conducted to address specific questions on SSCM, with four areas of focus:

1. Variable rate technology. Variable rate technology will involve using strip trials to evaluate variable phosphorus (P) and potassium (K) fertility, variable lime and pH, variable herbicide application, and variable varieties, etc.
2. Remote sensing. Remote sensing will involve the use of multiband, multispectral aerial photography to identify and characterize variability in yields, nutrient status, pest incidence, etc.
3. Crop modeling. Crop modeling will involve the use of crop models to aid in the understanding of significant spatial and temporal differences that affect crop yields and evaluate prescriptions under different weather years.
4. Economic analysis. Economic analysis will involve the analysis of data to aid producers in their decision making.

This project should provide answers to many questions related to the use of SSCM technologies and the benefits of using these different technologies in different areas of crop production.