CONTENTS. 



Department Bulletin No. 991.— Crop Rotation and Cultural Methods 



at Edgeley, N. Dak. — Continued. Page. 



Manured compared with unmanured fallow 14 



Green manure compared with bare fallow 14 



Sod crops 17 



The effect of the season on yields 19 



Continuous cropping compared with rotation 22 



Conclusions 22 



Department Bulletin No. 992. — Walnut Husk-maggot : 



Introduction , 1 



Brief description of insect and injury 2 



Synonymy 2 



Distribution 2 



Food plants , 3 



Description of life stages 3 



Activities of the flies 4 



Nature of injury 6 



Natural enemies 7 



Methods of control 7 



Department Bulletin No. 993. — The Composition of California 

 Lemons : 



The California lemon industry 1 



Purpose of investigation 2 



Investigational work 2 



Results of investigation 3 



Discussion of results 12 



Conclusions 18 



Bibliography 18 



Department Bulletin No. 994. — Methods op Conducting Cost of 

 Production and Farm Organization Studies : 



Introduction 1 



The uses of cost studies ; 2 



Basic elements of cost— 7 



Presentation of results 8 



The several methods of study . i 14 



The accounting method 15 



The survey method 39 



Combinations of survey and accounting methods 46 



Department Bulletin. No. 995. — The Beet-sugar Industry in the 

 United States in 1920 : 



Beet-sugar mills in the United States 1 



Soil 7 



Subsoil 8 



Topography 9 



Climate 10 



Sugar-beet stand 13 



Water , 19 



Drainage , 22 



Seepage 24 



Soil fertility , 26 



Crop rotation 30 



Competing crops , 32 



Farm equipment 35 



Beet by-products and live stock 41 



Labor problems 42 



The successful grower 44 



Diseases 45 



Insects 48 



By-products 49 



Roads 50 



Contracts 51 



Area competition 54 



Sugar-beet seed . 55 



Publications relating to sugar and its production 56 



