140 THE BOOK OP WHEAT 



(b) decomposing potash and phosphorus-bearing silicates, liber- 

 ating these two elements for plant-food; (c) affecting soils 

 physically, making them granulated, or loose and mellow; (3) 

 and that it decomposes sodium carbonate and thus breaks up 

 the so-called "black-alkali." 



Common Salt. This has also been used as a fertilizer for at 

 least several decades. In the eighties it was a common prac- 

 tice in England to sow salt in the early spring on wheat land 

 that was too rich, the idea being that a larger deposit of silica 

 in the stalk would result, enabling the wheat to stand better. 

 While it has been found a valuable agent for increasing the 

 yield of barley, it is of less importance in raising wheat. 



Miscellaneous Fertilizers. A great many other materials have 

 been used to a greater or less extent as fertilizers. Among them 

 are : Animal products, as wool waste and the refuse of modern 

 slaughterhouses, blood, bone, hair, horn, hoof, etc., which 

 with fish, manure and sulphate of ammonia from the gas works, 

 are still the main sources of nitrogen applied to crops; swamp 

 muck, marsh mud, sea-weed, sludge, poudrette, potassium, cot- 

 tonseed meal, rape-cake, burnt clay, charred peat, soot and 

 green manuring crops. The latter are simply plowed under, a 

 practice widely followed in the United States, especially with 

 alfalfa and other legumes. Where stock can be raised, green 

 crops and cottonseed meal have nearly as great a value for fer- 

 tilizer after feeding as before, and yield the additional inter- 

 mediate product of milk or beef. 



It is interesting to note that the aborigines taught the early 

 settlers of New England the value of fish as a fertilizer. Fish 

 or fish waste should be composted. Quicklime is used in 

 France. Fish compost readily yields its elements to growing 

 crops, consequently it should be applied in the spring, and not 

 deeply covered. Sludge is the precipitant of sewage, and 

 poudrette is the same reduced to a dry powder. A part of their 

 value lies in the germs of nitric ferment which they contain. 

 Some 40 tons of wheat straw leached and burned on the soil 

 contribute to it 8 pounds of phosphorus and 680 pounds of 

 potassium, besides the nitrogen leached into the soil before the 

 straw was burned. This immensely increases the yield of wheat. 

 Mulching with straw does not seem to be of any benefit to 

 wheat, whether applied for fertilizing or for winter protection. 



