FERTILIZERS 129 



Salt facilitates the absorbing power of soils, reacts with lime, 

 and serves as a solvent for phosphates. 



Gypsum (calcium sulphate) is a compound of calcium, sulphur, 

 and oxygen. When burned, it forms a white powder known as 

 plaster of Paris. When reduced to powder by grinding, it is 

 known as ground gypsum. It furnishes lime to the soil and 

 increases its solvent power. In the Eastern States large quantities 

 of gypsum are used in fertilizing clover fields. Large beds of 

 gypsum are found in western Oklahoma, New York, and Nova 

 Scotia. 



Marl is a mixture of sand and clay with varying proportions of 

 lime, phosphoric acid, and potash. A great deal of this kind of 

 soil is found in New Jersey and Virginia. Marl is a valuable 

 addition to soils on account of its mineral constituents and their 

 mechanical effect upon the soil. Both ground marl and gypsum 

 may be applied to the soil by a drilling machine specially adjusted 

 for the purpose or by a manure spreader. 



Wood Ashes. In timbered countries unleached wood ashes 

 form a cheap and valuable fertilizer. They contain much mineral 

 matter necessary for plant food, especially lime and potash. Both 

 of these elements exist in wood ashes in such a form as to be 

 readily available to the plant, and at the same time the ashes 

 exercise a beneficial mechanical effect on the soil by making it 

 mealy and easy to cultivate. 



Leather Meal is the waste product from leather factories where 

 shoes and other leather goods are manufactured on a large scale. 

 Its most valuable constituent is nitrogen, and it is a good fertilizer 

 for pastures and meadows. 



Felt Waste is one of the by-products in factories where felt goods 

 are manufactured. Its most valuable constituent is nitrogen. 



Hair Waste. This product may be obtained in very large 

 quantities in cities where the original materials are utilized for 

 manufacturing purposes and the hair remains as a waste product. 

 In the cities where the large packing houses are located hair waste 

 may frequently be purchased as low as two or three dollars a ton. 

 It contains nitrogen and is a valuable fertilizer for orchards and 

 pastures. 



Muck and Peat. In low wet places there frequently accumu- 



PRAC. AGRICUL. 9 



