102 SCHOOL AND HOME GARDENING 



legumes as peas, beans, cowpeas, and the common clovers. 

 Many soils require inoculation for alfalfa, soybeans, and some 

 few require it for red clover, some varieties of beans, and 

 others. In this experiment another legume may be used in- 

 stead of alfalfa. The principle may be brought out by heating 

 the soil in the cans or boxes by placing it in an oven hot enough 

 to kill all bacteria present. This vcill make the inoculated 

 plot show a marked difference in growth for any legume which 

 may be used. With peas, for example, the soil in one can may 

 b ' sterilized with heat and the other not sterilized. The 

 grovrth will then show the bacteria present in the latter but not 

 in the former. 



12. Lime for Legumes. — Prepare two similar areas as in the 

 preceding exercise. The soil for this is better if it is » heavy clay 

 or very black soil. If, when tested with litmus paper it is sour, 

 so much the better ( see exercise with litmus paper. Chapter X ) . 

 Apply a very light sprinkling of fine lime over the surface of one 

 plot and rake it in. Then grow some kind of legume such as cloven 

 or alfalfa until it is a few inches high. Observe the difference in 

 growth on the two plots. 



Does the growth show any marked difference? Is the 

 application of lime beneficial for the legume in this case ? The 

 exercise may be tried with several different legumes, as beans, 

 peas, soybeans, cowpeas, and others. It may also be repeated 

 with different types of soil to determine whether all kinds of 

 soils in the neighborhood are benefited by the use of lime. 



I 13. Amount of Mineral Matter in Plants. — Carefully weigh a 

 few ounces of very dry wood. Then place it on a stove shovel in the 

 stove and burn it, being careful to save all the ashes on the shovel. 

 Weigh the ashes -with the most delicate scales available. Nearly all 

 of the mineral matter of the wood is left in the ashes. 



The mineral parts of the plant come from the soil. The 

 exercise shows how small a part of the plant's food comes from 

 the soil. Nearly all of the remainder of the plant's food comes 

 from the air. It is usually considered that our farm crops 

 take 95 per cent of their gain in weight from the air. The 



