4 FICRTII^ITY AND FERTILIZER HINTS 



element is essential to plant growth and is found in the stems, 

 leaves and fruits of plants. 



Phosphorus is found in combination with oxygen and metals, 

 as phosphates. Vast deposits of phosphates are found in Tennes- 

 see, South Carolina, Florida and some of the western states. 

 It is present in many rocks and most soils and is an important 

 element for plant food. It exists in combination with organic 

 substances in plants and constitutes an important part of the ash 

 of plants. Bones, which contain about 60-65 P^^" cent, of cal- 

 cium phosphate, are an important source of phosphorus for plant 

 food. 



Calcium is an element which occurs in combination in many 

 substances as lime, marble, shells, coral and gypsum. It makes 

 up about one-sixteenth part of the earth's crust. Plants and 

 animals require this element, sometimes in larger amounts than 

 one would imagine. The bones of animals are made up largely 

 of this element in combination as lime. Lime is a great factor 

 in regulating the physical condition of soils. 



Sulphur. — This is a yellow substance which is found in the 

 free state in large deposits in Louisiana, western United States, 

 and Sicily. It is found in combination in gypsum (an important 

 indirect fertilizer), pyrites (a source of sulphuric acid), galena, 

 etc. It is also found in many natural waters. In plants it oc- 

 cupies an important place, occurring in organic compounds as 

 protein, or nitrogenous portions, and also as sulphuric acid. Most 

 of our soils are sufficiently supplied with this element for the 

 nourishment of plants. 



Silicon occurs in combination as sand, flint, quartz, etc., and 

 constitutes about one-half the earth's crust. It is present in most 

 rocks and soils and plays an important part in the physical make 

 up of the soil. Plants require this element to support certain 

 parts of their structure. The hulls and straws of plant sub- 

 stances are often comparatively rich in this element. 



Iron is a very common element and in combination it is widely 

 distributed. Although used in small amounts by plants it is 

 nevertheless very important, as it is necessary for the produc- 

 tion and activity of chlorophyll (the green coloring matter of 



