ELEMENTARY FORESTRY 



381 



FIG. 153. RELATION OF HUMUS TO 



GROWTH OF CORN 

 i, clay subsoil; 2, same with fertilizer; 



3, same, with humus. 

 (Photograph by C. L. Goodrich) 



which proves that forest loam is n per cent vegetable 

 matter. The soil from the barren field did not burn and, 

 on weighing, we found 

 99 grams, giving only i 

 per cent organic matter. 

 Put the burned samples 

 away in dry bottles, 

 of clear glass and simi- 

 lar size and shape, for 

 the school collection. 

 These are valuable speci- 

 mens that tell a long 

 story. Compare again 

 as to color and composi- 

 tion, so far as this can be 

 done by the unaided eye and by feeling with the fingers. 

 Are the samples not more alike than before they were 

 burned ? 



Have a few of the class fill a series of flowerpots or 

 boxes with different kinds of soil, as shown in Fig. 153, 

 and in them plant corn or other seeds. This work may 

 be varied in regard to soils and seeds planted. The plants 

 should stand together in one of the schoolroom windows, 

 where they may receive equal light and care. Observe 

 and possibly measure the growth from time to time. 



We have thus found that vegetable matter is the chief 

 constituent that makes the soil black and rich; and we 

 know that this comes from falling leaves and twigs and 

 from decaying roots of the forest. How long does it take 

 the trees to make rich loam ? In the main, this is a ques- 

 tion that the children will not find time to answer. They 



