SmiA'l'ION AND SOIL 59 



school children. Some bowsi gave an account of their inter- 

 esting work in tlie following words : 



W'e wanted to grow a patcli (if cowpeas. We sent to the laboratory 

 and secured a small packet of sterilized cotton fiber upon which nitrogen 

 bacteria were growing. We received, besides, two little packages of chem- 

 icals. We were told to dissoU'C one of these in a bucket of water and 

 then drop in the cotton containing the organisms. The next morning 

 we mixed in the second chemical. By simple division, the bacteria grew 

 so numerous as to make the water milk)'. This preparation was then 

 sprinkled on the seed just before planting. As the roots sprout, the 

 bacteria find their way to them. They at once begin taking in and 

 storing up the nitrogen in the atmosphere. 



Many such experiments are recorded.^ A common but 

 convincing test is to plant two strips with peas, treating one 

 with fertilizer and the other without. To quote one out of 

 many actual records, " The inoculated seed in the first row 

 did as well without fertilizers of any kind as the uninoculated 

 seed did in the second row, loaded as it was with fertilizers 

 at the rate of 800 pounds of phosphate." 



On the principle that a pound saved is a pound gained, no 

 careful gardener will underestimate the value of his compost 

 heap. A compost heap provides for the saving of ever}' 

 scrap of material which can by hook or by crook be turned 

 into plant food. And so in the autumn all old stalks and 

 withered leaves, in short everything that will in time make 

 soil, should be raked into a pile and given a chance to decay. 

 To hasten disintegration it is well to dampen it from time to 

 time, covering it o\'er with boards or with a barrel without a 

 head, so that it will not look unsightly. In fact, screened with 

 vines, this can even be made into an attractive corner. After 

 the pile has been decomptwing for several months, mix with 



1 In Miss Mailman's class, Rice School. 



2 United States Department of Agriculture, JiiiUiiiii .Wk 2/4. 



