230 GARDENS AND THEIR MEANING 



65 pounds of nitrogen, 2 1 pounds of phosphoric acid, and in 

 pounds of potash. (United States Department of Agriculture, 

 Farmers' Bulletin No. 16.) 



VI. COMMERCIAL FERTILIZERS FURNISH NITROGEN, PHOSPHORIC 

 ACID, POTASH, AND LIME 



Nitrogen is to be obtained from nitrate of soda, sulphate of am- 

 monia, dry fish, cottonseed meal, etc. 



Phosphoric acid is to be obtained from phosphate rocks, bones, 

 fish scraps, etc. . 



Potash is to be obtained from potash mines. Wood ashes con- 

 tain potash. 



Lime is supplied to the soil in the shape of quicklime. It is 

 valued chiefly for its effect on texture, making clay soils mealy and 

 sandy soils more adhesive. 



GENERAL CONCLUSIONS 



Small grains wheat, oats, and barley can easily obtain 

 phosphoric acid and potash, but they are weak in obtaining nitro- 

 gen and are benefited, therefore, by the addition of nitrates. 



Legumes collect nitrogen from the air, but take from the soil 

 lime, phosphoric acid, and potash. Hence these last must be 

 supplied by manures. 



Root crops are unable to use the insoluble mineral elements in 

 the soil. Hence all the chief elements may be advantageously ap- 

 plied in a state ready for use. 



Stem and leaf crops in particular require nitrogenous food. A 

 healthy green foliage indicates good nourishment ; pale yellowish 

 green indicates lack of nitrogen. 



Fruit trees are slow-growing plants and do not need quick- 

 acting fertilizers. Small fruits are rapid-growing plants and are 

 benefited by readily soluble fertilizers, 



