Volume 30, Bulletins 378-391. (378) Farm Family Housing Needs and Preferences in the North Central Region; (379) Agricultural Cooperatives in Iowa: Farmers' Opinions and community Relations; (380) Evaluation of Variance Components From a Group of Experiments with Multiple Classifications; (381) Returns From and Capital Required for Soil Conservation Farming Systems: A Study of a Specific Population of Farms and Soils; (382) Principles of Conservation Economics and Policy; (383) Economics of Crop Rotations and Land Use: A Fundamental Study in Efficiency with Emphasis on Economic Balance of Forage and Grain Crops; (384) Nutrient Uptake by Soybeans on Two Iowa Soils; (385) Defrosting and Cooking Frozen Meat; (386) Relationship of Crop-Share and Cash Leasing Systems to Farming Efficiency; (387) Demand and Diversity of Use of Electricity on 16 Farms in the Eastern Livestock Area of Iowa; (388) Resource Productivity in Iowa farming: With Special Reference to Uncertainty and Capital Use in Southern Iowa; (389) Cost of Manufacturing Butter: A Study Based on Data From 13 Iowa Creameries; (390) Substitution Relationships, Resource Requirements and income Variability in the Utilization of Forage Crops; (391) Some Obstacles to Soil Erosion Control in Western Iowa