AGRICULTUKE 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 ImpleTnents. , 



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 ? 



