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.—Jncreasing 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 Plan.ation. 
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 Anvmal 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 
