Proceedings of Symposium on Paddy Soils, Softcover reprint of the original 1st ed. 1981

China contributes a large part to rice production, one of the most important crops in the world. It is estimated that in China rice constitutes about half of the total food production, covering an area of about 30 % of \08 hectares of cultivated land of the whole country. Owing to the peculiar water regime, paddy soils possess quite different properties physically, chemically and biologically as compared with those of upland soils. Such properties have a conspicuous effect on fertility and management practice of paddy field. For the purpose of summing up the past work and opening up new prospects, a "Symposium on Paddy Soils" was organized under the auspices of Academia Sinica, held on October 19-24, 1980 in Nanjing, which was followed by a seven-day paddy soil excursion in the lower Changjiang Delta. In addition to 120 Chinese soil scientists, 56 guests coming from America, Asia, Europe and Oceania attended the symposium on invitation. A total of 110 papers were presented either orally or by poster. All these are collected and published in the present proceedings which we hope may be helpful to the scientific exchanges between soil scientists of China and other countries.

Preface.- I. Plenary Session.- Soil Factors That Influence Rice Production.- Some Characteristics of High Fertility Paddy Soils.- Rice Soils for Food Production.- Recent Progress in Studies of Soil Structure, and Its Relation to Properties and Management of Paddy Soils.- Some Aspects of the Physical Chemistry of Paddy Soils.- Oxidation-Reduction Properties of Paddy Soils.- The Role of Inorganic Redox Systems in Controlling Reduction in Paddy Soils.- Fertility of Paddy soils in Tropical Asia.- On the Genetic Classification of Paddy Soils in China.- The Classification of “Paddy Soils” as Related to Soil Taxonomy.- Principal Types of Low Yield Paddy Soil in China.- The Fertility and Fertilizer Use of the Important Paddy Soils of China.- Evaluation of Nitrogen Fertility and Increasing Fertilizer Efficiency in Wetland Rice Soils.- Cultivation and Application of Green Manure in Paddy Fields of China.- Cropping System in Relation to Fertility of Paddy Soils in China.- II. Section Session.- Section 1. Properties.- Some Laboratory Observations on the Formation of Black Layer in the Recently Reclaimed Saline Soils Under Rice Cultivation.- Reducing Organic Substances Responsible for Removal of Fe (III) and Mn (IV) From Subsurface Horizon of Lowland Rice Soil.- Voltammetric Determination of Reducing Substances in Paddy Soils.- Chemical Equilibria of Sulfides as Studied With a Hydrogen Sulfide Sensor.- Determination of Redox Potential (Eh) by Depolarizing Curve Method.- A Preliminary Study on Properties of Organo-Mineral Complex of Paddy Soils in Taihu Lake Region.- Determination of Lime Potential of Paddy Soils With Two Ion-Solective Electrodes.- The Availability of Micronutrients in Paddy Soils and Its Assessment by Soil Analysis Including Radioisotopic Techniques.- Section 2. Genesis and Classification.- A preliminary Study on Specific Adsorption of Cu Ion by Paddy Soils of Southern Jiangsu Province.- Studies on Accumulation of Strontium-90 in Paddy Soils.- Residual BHC in Paddy Soils and Its Contamination to Rice.- Decomposition of Plant Materials in Relation to Their Chemical Composition in Paddy Soil.- Some Physical Properties of Paddy Profiles in Taihu Lake Region.- Hydrologic Status of Paddy Fields During Rice-Growing Period.- Release of Nitrogen From Decomposing Legume Roots and Nodules.- Investigation on Ecological Distribution of Fungi in Paddy Soils.- Mechanisms of Bacterial Iron-Reduction in Flooded Soils.- Investigation on Nitrogen-Fixing Bacteria in Rice Rhizosphere.- Biological Nitrogen Fixation Associated With Wetland Rice.- Studies on the Preparation of Dried Inoculum of Blue-Green Algae and Its Application in Paddy Field.- Preliminary Studies on Process of Nitrogen Excretion by Azolla.- On Ecological Distribution of Bacteria in Paddy Soils.- Iron Toxicity in Rice Plants and Nitrogenase Activity in the Rhizosphere as Related to Potassium Application.- Principles of Classification as Applied to Paddy Soils.- Classifying Rice Soils on the Basis of Their Physiological Characteristics.- The Recent Trend of Paddy Soil Classification in Japan.- Paddy Soils in Chengdu Plain and Their Classification.- The Application of Cluster Analysis to the Material Classification of Paddy Soils in Taihu Lake Area.- Section 3. Management.- Evolution and Development of Alluvial Paddy Soils in Zhujiang Delta.- On the Classification of Basic Categories of Paddy Soils in Taihu Lake Region.- Characteristic Features of Paddy Soils of Japan.- On the Classification and Use of Some Dark Clayey Paddy Soils In China.- On the Genesis, Characteristics and Utilization of the Acid Sulphate Paddy Soil in China.- Some Chemical Properties of Soils From the Taoyuan Prefecture, China, in Particular Their Fertility.- On the Characteristics of Leaching and Accumulation of Chemical Elements in Two Eutric Paddy Soils in Taoyuan County, Northern Hunan Province.- Effects of Neotectonic Movement on Development of Paddy Soils in Changjiang Delta.- Characteristics of Geographical Distribution of Fertile Paddy Soil in Fujian Province.- Micromorphological Features as the Indication of the Fertility of Paddy Soils.- Differentiation of Iron Oxide in Paddy Soils in Taihu Lake Region.- Changes in Clay Minerals in the Genesis of Paddy Soils.- Clay Minerals of Paddy Soils in Taihu Lake Region.- On the Characteristics of Fe-Organic Coating in Paddy Soils.- The Magnetic Susceptibility Distinction of Paddy Soils in Taihu Lake Region.- Effect of Long-Term Rice Cultivation on Some Properties of Soda Solonchaks at Qian Gorlos Irrigation Region of Jilin Province in China.- On the Tendency of Organic Matter Accumulation in Paddy Soil Under Triple Cropping System in Suburbs of Shanghai.- Stagnancy of Water in Paddy Soils Under the Triple Cropping System and Its Improvement.- Drainage of Paddy Soils in Taihu Lake Region.- Improving Rice Seedling Emergence in Flooded Soil by Use of Calcium Peroxide.- Rice Fertilization and Wastewater Nutrients Recycling.- The Study of Nitrogen Distribution Around Rice Rhizosphere.- Fertilizer Management of paddi Soils with Physical Constraints.- III. Poster Session.- Rationalization of Fertilizer Application to Rice in a Cool Environment.- Transformation and Distribution of Organic and Inorganic Fertilizer Nitrogen in Rice and Soil System.- Transformation of Fertilizer, Straw and Soil Nitrogen in Paddy Soil.- Nitrogen Efficiency Study Under Flooded Paddy Conditions: A Review of Inputs Study I.- The Fate of Nitrogen Fertilizer in Paddy Soils.- Potassium Status of Paddy Soils in Some Countries of South and East Asia.- On the Potential of K-Nutrition and the Requirement of K-Fertilizer in Important Paddy Soils of China.- Biochemical and Nutritional Diagnosis of K-Deficiency of Paddy Rice Plants With Regard to Soil Fertility.- Sulphur Content and Distribution in Paddy Soils of South China.- The Status of Microelements in Relation to Crop Production in Paddy Soils of China: III. Zinc.- A Report on the Saling-Sodic Soils of Baigezhuang and the Zinc Deficiency of Paddy Crop.- Some Methods to Minimize Zinc Deficiency in Transplanted Wetland Rice.- Development of the Zinc Extension Component for Irrigated Rice in the Philippine Masagana 99 Production Program.- On Zinc Deficiency of Paddy Soils.- Recovery of Fertilizer-Nitrogen by Rice Grown in A Greenhouse Under Varying Soil-and Climatic Conditions.- Effect of Water Conditions and Organic Matter on Modulus of Rupture of Paddy Soils.- The Effect of Water-Stable Aggregates in Various Sizes on Air and Water Regime of Soils.- Influence of Transformation of Iron Oxides on Soil Structure.- Determination of Stability Constant of Mn (Il)-Complex by Voltammetric Method.- Determination of pH of Paddy Soils in situ.- Mercury Pollution of Some Paddy Soils.- Effect of Nitrogen Sources on Some Physiological Characteristics of Azolla.- Studies on Nitrogen Fixation by Association of Bacteria With Rice Root.- Geographical Distribution of Paddy Soils in China.- Characteristics of Some Types of Paddy Soil in Northeast China.- The Formation and Characteristics of Cold Spring Paddy Soil.- Genetic and Anthropogenic Characteristics of Paddy Soils Derived From Swampy Land in Lixiahe District, Jiangsu Province.- Geochemical Characteristics of Some Transitional and Rare Earth Elements in Paddy Soils of Red Earth Region, Guangdong Province.- Preliminary Studies on Primary Minerals of Some Paddy Soils in Taihu Lake Region.- Double Cropping of Rice in Triple Cropping System and Soil Fertility.- Characteristics of High-Yield Paddy Soils in Suburbs of Shanghai.- On the Forming of Waterlogged Condition in the Cultivated Horizon of Paddy Soils in Shanghai During Dry Farming Period and the Approach to Its Elimination.- A Comparative Study on Methods of Tillage of Paddy Soils in Taihu Lake Region.- Effect of Rice Planting on Improvement and Utilization of Saline Soils in Tarim Basin.- On Rice Nutrient Disorder and Its Diagnosis in China.- Characteristics of Nitrogen Mineralization of Paddy Soils and Their Effect on the Efficiency of Nitrogen Fertilizer.- Uptake of Nitrogen by Rice Plant From Straw Manure, Urea and Soil.- Phosphorus Balance on Paddy Soils Reclaimed From the Salinized Waste Land, Northern Jiangsu.- A Study on the Responses to Fertilizer Potassium on Paddy Soils in Guangdong Province.- Iron and Chromium Uptake by Crops on Well Drained Soils and on Poorly Drained Wetland Soils.- The Status of Microelements in Relation to Crop production in Paddy Soils of China: I. Boron.- The Status of Microelements in Relation to Crop Production in Paddy Soils of China: II. Molybdenum.- Effect of Nitrapyrin on the Inhibition of Nitrification in Some Paddy Soils of China.- Effect of Soil Fertility on the Growth and Yield of Rice.- Appendics (Speeches in Closing Session).- China and the International Community of Soil Science.- Soils and People.- Some Remarks on the Development of Soil Science in China.