AGRICULTURE FOR SOUTHERN SCHOOLS. 35 
Lesson 20. — Buying Farm Equipment. 
1. Local dealers v. mail-order houses. 
2. Cash payment v. credit. 
3. Cooperation in buying. 
Lesson 21. — Increasing Production. 
1. Relation of acre yield to profit. 
2. Relation of production to prices. 
3. Factors in crop increase. 
Lesson 22. — Maintenance of Fertility. 
1. Obligations to coming generation. 
2. Ways of increasing productivity. 
3. Relation to farm management. 
4. Restoring lost fertility. 
5. Preventing erosion. 
Special references. — The Mangum Terrace in Its Relation to Efficient Farm Man- 
agement, Bureau of Plant Industry Circular 94. Also, the following Farmers' Bulle- 
tins: 257, Soil Fertility; 326, Building up a Run-down Cotton Plantation. 
Lesson 23. — Live Stock and Soil Fertility. 
1. Animal products v. plant products in relation to plant food. 
2. Value of barnyard manure. 
3. Care and use of barnyard manure. 
Special references. — The Function of Live Stock in Agriculture, Yearbook 1916. 
The following Farmers' Bulletins: 192, Barnyard Manure; 614, A Corn-belt Farm- 
ing System Which Saves Harvest Labor by Hogging Down Crops; 704, Grain Farm- 
ing in the Corn Belt with Live Stock as a Side Line. 
Lesson 24. — Economics of Animal Production. 
1. Live stock as a means of marketing low-priced crops. 
2. Live stock and cheap labor. 
3. Relation of live stock to type of farming and size of farm. 
Special reference. — Cropping Systems for Stock Farms, Yearbook 1907. 
Lesson 25. — Some Live-Stock Problems. 
1. Pure-bred v. grade stock. 
2. Breeding animals v. market stock. 
3. Depreciation and increase in value of stock. 
Special references. — The following department Bulletins: 49, The Cost of Raising 
a Dairy Cow; 413, Influence of Age on the Value of Dairy Cows and Farm Work 
Horses. 
Lesson 26. — Rotation of Crops. 
1. Benefits of crop rotation. 
2. Essentials of a good system. 
Lesson 27. — Rotation of Crops — Continued. 
1. Classification of crops. 
2. General rotations. 
Lesson 28. — Rotation of Crops — Continued. 
1. Rotations for the cotton belt. 
2. Rotations for special farms. 
Special references. — Suggested Cropping System for the Black Lands of Texas, 
Bureau of Plant Industry Circular 84. Planning Cropping Systems, Bureau of 
