AGRICULTURE FOR SOUTHERN SCHOOLS. 15 
Record and report: Each student should keep a record of the 
weights of the cans, tabulating results to show loss by days and the 
total loss in a comparative way. In his report he should explain why 
the various forms of mulching check evaporation and make applica- 
tion of the principles to results in field practice. 
Note. — Preliminary to this exercise the effects of a mulch may be demon- 
strated by putting powdered sugar on the top of a cube dipped in colored water, 
as suggested in connection with Exercise 10. 
Lesson 15. — Tillage Implements. 
1. The plow and its use. 
2. Harrows and cultivators and their use. 
3. Rollers and planters and their use. 
4. Hoes and other hand tools. 
Illustrative material: Catalogues of implement dealers (or a visit to 
such dealers). 
Lesson 16. — Drainage. 
1. Drainage of farm land a national problem. 
2. Benefits of drainage. 
3. Economics of drainage. 
Lesson 17. — Drainage — Continued. 
1. Drainage systems. 
2. Tile drainage. 
Special reference: Tile Drainage on the Farm, Farmers' Bulletin 524. 
Exercise 13. — Influence of Drainage on Plant Growth. 
Purpose : To show the effect of an outlet for surplus water. 
Directions : Use two plants nearly identical in size and variety in 
pots of the same size filled with similar soil. Stop up the hole in the 
bottom of one pot with wax and leave the other open with some 
pieces of broken flower pot or a layer of coarse gravel covering the 
bottom of the pot. Give the plants an abundant supply of water, 
the same amount to each plant. The temperatures of the soil of each 
pot should be taken by placing the bulb of a thermometer 2 inches 
below the surface and taking readings each day. After the effects of 
a lack of drainage are noted on one of the plants the pots should be 
changed, care being taken not to disturb the soil about the roots of 
the plants, the watering continued, and the effect noted. 
Record and report: A record should be made of the effects of the 
water upon the plants and the temperature of the soil. A written 
report should explain the cause of the condition of the plants in an- 
swer to the following questions: Why do most plants fail to grow 
well in undrained soil? What has the temperature of the soil to do 
with the difference in growth of the two plants? What is the effect 
of changing conditions with regard to drainage? How may the 
principles and practice of this exercise be applied to field conditions ? 
