160 CHILDREN'S GARDENS 



years to bring the fertility of a worn-out farm back 

 to the point where man found it, if left to Nature 

 alone. 



Nature, however, shows the kind of things to do 

 to make a fertile soil, and those who look closely and 

 reason, and then act, can furnish the supplies for her 

 laboratory, so as to save time and get larger results. 



Nature needs humus in a fertile soil. Bring the 

 material and save generations of time she would take 

 to collect it. Save all the manure, dead leaves, grass 

 and animals. 



Nature takes a very long time to make this mate- 

 rial into small enough pieces for humus. So break 

 it up for her. 



Humus must be decaying and damp. Let us start 

 the decay, and keep the material damp. 



This material must be in the soil. Spread it on 

 the ground and plow, or spade, it in. 



Nature wants it thoroughly mixed. Cultivate the 

 earth with tools, sometimes deep, and sometimes shal- 

 low, several times each year. 



Some gardeners and farmers keep a pit Into which 

 everything organic that will easily decay, is thrown. 

 Here it is kept wet and slowly changes into good 

 material for humus, and this is then mixed with the 

 soil. 



Commercial fertilizers. There are four elements 

 of plant food which are used up faster than the others, 

 and which some soils do not supply in large enough 



