Sometimes it is necessary to furnish phosphorus in the form of acid 

 phosphate or superphosphate. In this form most of it is available. It 

 should be applied at planting time in quantities ranging from fifty to 

 one hundred fifty pounds per acre. Rock phosphate is also a source of 

 phosphorus. It should be applied after being made in a compost with 

 barnyard manure, or be plowed under the previous fall with a heavy 

 growth of clover or pea vines. 



Humus 

 Humus is an organic substance which cannot be dispensed with. It 

 contains nitrogen; in fact, where it does not exist, there is little or no 

 nitrogen. It is necessary to maintain soil bacteria; it influences the 

 temperature of the soil, assists in absorbing water, and improves the 

 tilth of the soil. Humus can be maintained in the soil by applying 

 barnyard manure and plowing under vegetable growths. 



Lime 



While lime is not a plant food, it is necessary that it be in the soil, and 

 is classed as an indirect fertilizer. It is just as essential to plant life and 

 growth as nitrogen, phosphoric acid or potash. A very small per cent 

 of lime is found in grains, but a considerable amount is found in the sub- 

 stance of the plant. If a seed is planted in soil absolutely devoid of 

 lime, the growth is checked as soon as the lime is exhausted from the 

 seed. If a soil is deficient in lime, the plant is correspondingly deficient. 



Soil may be rich in all of the essential elements, namely, nitrogen, 

 phosphorus and potash, and still be worthless for agricultural purposes 

 if it does not contain a sufficient amount of lime. Corn grown on land 

 which does not contain a reasonable amount of lime will have small, 

 long-jointed stalks, small, delicate leaves, and a deficient ear. It is safe 

 to say that the productiveness of many of our fertile farms is reduced 

 fifty per cent simply because they do not contain the required amount 

 of lime. 



Lime not only neutralizes acids, but makes available other elements, 

 and improves the physical condition of the soil. Most corn lands, 

 especially those in the Mississippi river territory, need lime. 



Other Elements 



All of the other inorganic elements mentioned as component parts of 

 fertility exist in the soils of the United States in abundance. 



Farm Manure 



From every standpoint, farm manure is an ideal fertilizer for corn, 

 and the farmer who ignores it will certainly fail to secure what he is 

 entitled to from his land. Ordinary barnyard manure contains, not 

 only the inorganic plant food elements and nitrogen, but carbohydrates 

 and fiber, both of which are necessary to maintain fertility. 



