This monograph is the first effort by the American Society of Agronomy, Crop Science Society of America, and the Soil Science Society of America to publish a book on the use of computer simulation to evaluate agronomic systems. It is a testament to the desire of agronomists to enter a new era of agricultural research and development; a time in which simulation partially substitutes for experiments to determine recommendations for various agrotechnology packages. Improved accuracy in simulating crop and soil systems has convinced a growing number of researchers and technologists of the importance of being able to predict outcomes needed in agricultural decision making. Combining the soil, plant, and climate system into quantitative terms that lead to accurate predictions of outcomes is needed as agronomists enter the information age.
The main focus of agronomic research and development efforts in the past few decades has been related to food and feed production. The quality of the environment has now become an imperative issue that crop and soil scientists must address, in addition to maintaining adequate food production. The research needed to find management strategies that optimize high production and minimize environmental degradation will need to include simulation of all or part of the soil-plant atmosphere system. Experimental research alone would require more than an order of magnitude of effort and resources as compared to present levels of production and agricultural activity to adequately reach these goals. An era of low funding for agricultural research and extension makes the use of simulation models even more of a necessity as a major assistance tool for helping with decision making in sustainable agricultural systems. Progress made by using models is much faster and less expensive than through experimental research alone. Key simulated results, however, must continue to be evaluated with field experiments.
The chapters in this monograph have been written to provide examples of models of component processes necessary to simulate the dynamics of crop and soil systems. The information is intended to be useful to researchers, extension and other professional technologists, and teachers. For researchers, the models of processes will define details regarding information necessary from experimental trials to adequately simulate results of those experiments. Because every step in a simulation must be clearly defined, the lack of accuracy in simulating various processes also helps to identify gaps where additional research is needed. For professional agronomists who recommend technological packages to farmers and other users of crop and soil information, models could provide reasonable and quick answers to the "what if' questions for specific soil, crop, and management combinations. For teachers, the use of computer simulation models can provide stimulating opportunities for students to learn about details of dynamic processes and how the processes can be linked together to produce a desired system. Models of crop and soil systems also provide a means of doing simulated experiments in the classroom setting that would be impossible to do in the field within the time constraint of a crop year.
Chapters in this monograph have generally been organized to cover the plant processes first, then the soil processes, and finally to give some examples of how simulation models can be applied to problem-solving situations. Users of the information should realize there are different levels of detail in simulation models and different methods to approach the modeling of a process. Most of the authors have identified models other than their own from the literature that simulate the same process. Our examples of models of processes in the book are not necessarily at the same level of detail. Thus, the use of each modelled process to form a system might lead to an unbalanced analysis of the system. The user should seek models of processes treated at approximately the same level of detail for building a complete system model. We have intentionally provided some variation in level of detail in modelled processes to provide a range of examples of approaches to modeling.
J. T. Ritchie, co-editor
Dep. of Soil Science
Michigan State University
East Lansing, Michigan
R. J. Hanks, co-editor
Soils and Biometeorology Dep.
Utah State University
T. J. Arkebauer, Assistant Professor, Department of Agronomy, University of Nebraska, Lincoln, NE 68583-0817
W. L. Bland, Assistant Professor, Blackland Research Center, Texas Agricultural Experiment Station, 808 East Blackland Road, Temple, TX 76502
K. J. Boote, Professor of Agronomy, Agronomy Department, University of Florida, Gainesville, FL 32611
Eshel Bresler, Professor and Director, Institute of Soils and Water, ARO, Volcani Center, P.O. Box 6, Bet Dagan 50-250, ISRAEL
G. S. Campbell, Professor of Soils, Department of Agronomy and Soils, Washington State University, Pullman, WA 99164
Sang-Ok Chung, Post-Doctoral Researcher, Agronomy Department, Iowa State University, Ames, IA 50011. Currently Assistant Professor, Department of Agricultural Engineering, Kyungpook National University, SOUTH KOREA
Mark J. Cochran, Associate Professor of Agricultural Economics, Department of Agricultural Economics, University of Arkansas, Fayetteville, AR 72701
M. Nour El Din, Postgraduate Researcher, Department of Land, Air, and Water Resources, University of California, Davis, CA 95616
D. C. Godwin, International Fertilizer Department Center, Muscle Shoals, AL 35660. Currently Alton Park, MS-2, Dubbo, NSW 2830, AUSTRALIA
R. J. Hanks, Professor of Soil Physics, Plant, Soil, and Biometeorology Department, Utah State University, Logan, UT 84322-4840
Robert W. Hill, Professor, Agricultural and Irrigation Engineering, Utah State University, Logan, UT 84322-4105
Robert Horton, Associate Professor of Soil Physics, Agronomy Department, Iowa State University, Ames, IA 50011
S. S. Jagtap, Agroclimatologist, International Institute of Tropical Agriculture, Oyo Road, PMB 5230, Ibadan, NIGERIA
C. Allan Jones, Resident Director of Research and Professor, Blackland Research Center, Texas Agricultural Experiment Station, 808 East Blackland Road, Temple, TX 76502
James W. Jones, Professor of Agricultural Engineering, Agricultural Engineering Department, University of Florida, Gainesville, FL 32611
J. R. Kiniry, Research Agronomist, USDA-ARS, SPA, 808 East Blackland Road, Temple, TX 76502
J. W. Mishoe, Professor of Agricultural Engineering, Agricultural Engineering Department, University of Florida, Gainesville, FL 32611
D. S. NeSmith, Graduate Research Assistant, Department of Crop and Soil Sciences, A572 Plant and Soil Sciences Building, Michigan State University, East Lansing, MI 48824-1325
J. M. Norman, Professor of Soil Science, Department of Soil Science, University of Wisconsin, 1525 Observatory Drive, Madison, WI 53706
Lucas D. Parsch, Associate Professor, Department of Agricultural Economics, 225 Agriculture Building, University of Arkansas, Fayetteville, AR 72701
V. Philip Rasmussen, Associate Professor and Assistant Department Head, Plant, Soil and Biometeorology Department, Utah State University, Logan, UT 84322-4820
J. T. Ritchie, Professor, Homer Nowlin Chair, Department of Crop and Soil Sciences, A570 Plant and Soil Sciences Building, Michigan State University, East Lansing, MI 48824-1325
Charles W. Robbins, USDA-ARS, 3793 North, 3600 East, Kimberly, ID 83341
H. Don Scott, Professor of Agronomy, Department of Agronomy, 115 Plant Science, University of Arkansas, Fayetteville, AR 72701
Andrew N. Sharpley, Soil Scientist, USDA-ARS, Water Quality and Watershed Research Laboratory, P.O. Box 1430, Durant, OK 74702
R. Wayne Skaggs, William Neal Reynolds Professor, Department of Biological and Agricultural Engineering, North Carolina State University, Box 7625, Raleigh, NC 27695-7625
Edward L. Skidmore, Soil Scientist, USDA-ARS, Wind Erosion Research, Department of Agronomy, Kansas State University, Manhattan, KS 66506
K. K. Tanji, Professor of Water Science, Department of Land, Air, and Water Resources, University of California, Davis, CA 95616
Kalven L. Trice, Graduate Research Assistant, Department of Agricultural Economics, University of Arkansas, Fayetteville, AR 72701. Currently Agricultural Economist, USDA-SCS, 10417 Campus Way South, Upper Marlboro, MD 20772
J. R. Williams, Hydraulic Engineer, USDA-ARS, Grassland, Soil and Water Research Laboratory, 808 East Blackland Road, Temple, TX 76502