In the past 10 years, there has been a resurgence in interest in soil management and conservation of the soil resource. With the knowledge we have accumulated in the past 100 years, there is the possibility of developing new and innovative ways of effectively managing the soil. The emphasis on sustainable agriculture requires that we understand how to utilize the soil as a viable living resource. To meet the world demand for food within the next 50 years requires a healthy and strong soil resource which can sustain production. With the dedication of the National Soil Tilth Laboratory in 1989, it was decided that one contribution the laboratory could make to agri cultural science would be to foster an exchange of information on soil management. The focus of that interchange centers on long-term soil management. If we are to fulfill the goals of sustainable agriculture, environmental quality, and feeding the world, there will have to be an increased understanding of how to effectively manage the soil. Long-term soil management requires integrated and interdisciplinary research to bring all of the information together in terms which would be applicable to all soils. To accomplish this goal a workshop is held each year, with the exchange of information focusing on a single topic within the framework of developing effective strategies for long-term soil management. With the forum to focus on an individual theme each year, the theme for the initial workshop was "Limitations to Plant Root Growth.

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Development and Growth of Crop Root System.- I. Introduction.- II. Monocotyledonous Root System.- III. Dicotyledonous Root System.- IV. Needed Research.- References.- Soil Environment Constraints to Root Growth.- I. Introduction.- II. The Rhizosphere Environment.- III. Root System Morphology.- IV. Root-Soil Interactions.- V. Conclusions.- References.- Root Function in Water Transport.- I. Introduction.- II. Water Entry into Roots.- III. Root Function During Drought.- IV. Concluding Remarks.- References.- Wheel-Induced Soil Physical Limitations to Root Growth.- I. Introduction.- II. Soil Physical Limitations to Root Growth.- III. Extent and Influence of Wheel Traffic.- IV. Root Growth.- V. Root Growth and Crop Yield.- VI. Subsoil Compaction.- VII. Conclusions.- References.- Soil Chemical Factors Limiting Plant Root Growth.- I. Introduction.- II. Soil Chemical Factors.- III. Solving the Shallow Rooting Problem.- IV. Challenges for Future Research.- V. Summary.- VI. Acknowledgments.- References.- Root Extraction of Nutrients Associated with Long-Term Soil Management.- I. Introduction.- II. Effects of Long-Term Soil Management on Root Extraction of Nutrients.- III. Interaction Among Management Factors.- IV. Modeling Long-Term Management Effects on Root Extraction of Nutrients.- V. Conclusions.- References.