SOIL 141 



the farmer increase the amount of humus in his soil, 

 and thus the drawing and holding capacity for water be 

 increased ? 



5. Soil Mulch 



Fill two tin pans or cans with the same kind and 

 amount of soil, and thoroughly saturate each pan of 

 soil with water. Then cover the wet soil of one pan 

 with an inch or more of dry earth, finely pulverized, 

 and leave the other pan unmulched. See that both 

 pans of soil now weigh the same, by transferring soil 

 from one to the other as necessary. Set the pans aside 

 for twenty-four hours, then weigh again. Weigh the 

 pans every twenty-four hours for several days, and 

 record the comparative weights of the two pans of soils. 

 The dust mulch prevents evaporation, and enables the 

 soil to retain its moisture. What bearing does this ex- 

 periment have upon any farm operations? 



6. Field Observations 



Take a walk to a suitable field near the schoolhouse. 

 Take pencil and notebook and answer the following 

 questions : 



1. How does the weathered surface of rocks compare 

 with the freshly broken surface? 



2. Are the boulders and pebbles you find of the 

 same material as the rock ledges to be found in the 

 neighborhood ? 



3. How do the pebbles in the bed of a stream com- 

 pare with those back from the stream, in size and shape ? 

 Explain the difference. 



4. Find some rich soil and dig a hole about 18x12 



