312 AGRICULTURE 



water channels and result in waste of soil and washing out 

 of the seed or plants. 



Gullies once started should be leveled immediately by 

 use of the plow or other form of cultivation. Pack 

 straw, hay, or manure at the head of the channel, or at 

 intervals along its course, as this will do much to stop 

 the erosion, especially if used in time. Sheet, or sur- 

 face, washing is, however, a source of greater damage 

 than the formation of gullies. For sheet erosion, though 

 gradual, is constant on the slopes of all tilled fields. 



TOPICS FOR INVESTIGATION 



1. Select a spot on your home farm representing its 

 typical soil, dig down with a spade or soil auger and take 

 two samples, one from a depth of six inches, and one of 

 twenty inches. How do the samples differ (1) as to texture, 

 (2) as to organic matter, (3) as to structure? How deep 

 does the humus extend? Bring samples to school, and 

 compare with those from the different farms represented. 



2. Place some of each sample in a bottle or glass of 

 water and mix well. Allow the sand to settle (How long?), 

 and pour the water off the top into a third receptable. Allow 

 the clay to settle until the water becomes clear. (How long 

 is required?) Now determine as nearly as you can what are 

 the proportions of clay, silt and sand in the soils. How 

 would you name the texture of the soil on your farm ? 



3. Secure a sample of the soil from some cultivated hill- 

 top, and examine it for its texture, structure and the 

 amount of organic matter. Compare with another sample 

 taken from the foot of the hill. Explain the difference in 

 color. Dig down with a spade and compare the depth to 

 which the humus extends in each case. 



4. Are there any cultivated hills on your farm so 

 steep that erosion is considerable? If so, how does 

 the yield on the hill compare with the lower land? Are 

 there any gullies forming? If so, how long have they been 

 washing out? What is being done to stop them? 



