Front Cover; Advances in Agronomy, Volume 33; Copyright Page; Contents; Contributors to Volume 33; Preface; CHAPTER 1. CONSERVATION TILLAGE SYSTEMS; I. Introduction; II. Historical; III. Tillage Equipment and Use; IV. Crop Yields and Quality; V. Environmental Consideration; VI. Infiltration and Water Conservation; VII. Weed Control; VIII. Insects and Plant Diseases; IX. Soil Temperature; X. Soil Structure and Other Physical Properties; XI. Chemical Effects and Microbial Activity; XII. Economics; XIII. Summary and Conclusions; References; CHAPTER 2. POTASSIUM IN CROP PRODUCTION.

I. IntroductionII. Potassium Availability in the Soil; III. Potassium in Physiology; IV. Potassium Application and Crop Growth; V. Conclusions; References; CHAPTER 3. UTILIZATION OF WILD SPECIES FOR CROP IMPROVEMENT; I. Introduction; II. Biosystematics; III. The Gap between Hybridization and Utilization; IV. Approaches for Utilizing Wild Germplasm Resources; V. Examples of Species Used in Wild Species Hybridization Programs; VI. Specific Uses of Wild Species for Crop Improvement; VII. Summary and Conclusions; References; CHAPTER 4. NITROGEN FIXATION IN FLOODED SOIL SYSTEMS, A REVIEW.

I. IntroductionII. Nitrogen Fixation in the Water Column and on the Soil Surface; III. Nitrogen Fixation in the Aerobic Layer of Flooded Soil; IV. Nitrogen Fixation in the Anaerobic Layer of Flooded Soil; V. Nitrogen Fixation in the Root Zone of Nonnodulated Plants; VI. Nitrogen Fixation on the Leaf and Stem Surface of Plants; VII. Environmental Factors Influencing Nitrogen Fixation in Flooded Soil; VIII. Comparison of Acetylene Reduction and 15N Methodology; IX. Contribution of Fixed Nitrogen to the Nitrogen Requirements of plants; X. Perspectives; References.

CHAPTER 5. EXPERIENCE WITH SOIL TAXONOMY OF THE UNITED STATESI. Introduction; II. General Reactions to the System; III. Use of Soil Taxonomy Internationally; IV. Problems for Users of Soil Taxonomy; V. Taxonomic Problems; VI. Impact of Soil Taxonomy Internationally; VII. Summary; References; CHAPTER 6 .COMPETITIVE ASPECTS OF THE GRASS-LEGUME ASSOCIATION; I. Introduction; II. Competition in the Pasture Community; III. Physiological Considerations; IV. Morphological Considerations; V. Competition for Environmental Factors; VI. Conclusions; References.

CHAPTER 7. NITROGEN LOSSES FROM TOPS OF PLANTSI. Introduction; II. Record of Observed Decreases of Nitrogen Content of Plant Tops; III. Possible Pathways of Nitrogen Losses from Tops; IV. Associated Methodology Problems; V. Conclusions; References; CHAPTER 8. AGROTECHNOLOGY TRANSFER IN THE TROPICS BASED ON SOIL TAXONOMY; I. Introduction; II. The Transfer of Agrotechnology; III. Soil Classification in Perspective; IV. Agrotechnology Transference Research; V. Quantitative Verification of Transferability within a Soil Family; VI. Prerequisites for Worldwide Agrotechnology Transfer.