Nature-Study Agriculture 



mal matter in the soil. 

 All that is necessary to 

 get them working is to 

 supply them with plenty 

 of food. They are espe- 

 cially fond of manures, 

 and they also like straw 

 and stubble. Hence, if 

 stalks, straw, and other 

 refuse are plowed under 

 instead of being burned, 

 these bacteria will feed 

 on them, and the amount 

 of nitrogen in the soil 

 will be increased. 



Experiments and Obser- 

 vations 



i. From a damp, shady 

 place in a forest or from 

 under bushes, collect soil 

 which is rich in humus. 

 Examine it for decaying 

 leaves and similar matter. 

 Plant some seeds in it and 

 notice their rapid growth. 



2. Evaporate a cup of clear well water to show that it con- 

 tains earthy matter in solution. 



3. See how many different plants you can find that have nodules 

 on the roots. Do these plants have flowers similar to those of 

 peas ? Is their seed in pods like those of beans or peas ? 



4. Find out what kinds of legumes, if any, the farmers in your 

 neighborhood plant to enrich their orchards and fields. 



W. T. Stilling 



FIG. 31. A pure culture of soil bacteria 

 sufficient for an acre of clover. 



