IO2 SOILS 



decomposing effects on the mineral substances of the soil. 

 It has been shown by experiment that lime decomposes 

 certain compounds in the soil, thereby releasing stored 

 plant food. This is especially true of potassium com- 

 pounds secured in the soil silicates. When lime is added 

 to the soil, these silicates are decomposed and the potas- 

 sium therein is rendered available plant roots are served 

 what heretofore has been denied. You should bear in 

 mind, however, that lime has no power for supplying 

 potassium : it renders available only such material as al- 

 ready is present in the soil. 



Lime works in harmony with the phosphorus com- 

 pounds of the soil, also. It does so in this manner: Solu- 

 ble phosphorus combines freely with other elements 

 iron and aluminum, for instance. But these are undesir- 

 able compounds for the reason that they are insoluble, 

 and consequently plants reject them as food. Lime, on 

 the other hand, attracts the soluble phosphorus more 

 energetically than does iron or aluminum, and so helps 

 the plant because the plant fancies the products that lime 

 and phosphorus together make. Now, this is a good 

 reason why lime should be given freely to the soil. 



You will find, also, that lime is an extremely valuable 

 agent in helping the decomposition of organic matter in 

 the soil. While organic matter is useful and a necessary 

 component of every good soil, still we must not forget 

 that much valuable plant food is stored in this organic 

 matter, and that a part of it, at least, should be turned 

 over to plants each year, its replacement to take place 

 subsequently by other and additional donations. Much 

 of the nitrogen content of the soil is obtained through this 

 destruction of organic matter. Hence, it is well to keep 

 this supply in mind. 



Lime promotes good texture. With old soils, espe- 



