Manures and Fertilizers 131 



causing them to dry out, particularly in dry years and 

 dry climates. 



A practice in handling manure that is gaining ground is to 

 apply it to the hay crop preceding potatoes in the rotation. 

 By increasing the yield of the hay, the organic matter left 

 in the soil by the roots, stubble and aftermath is increased 

 for the use of the potatoes later. When manure is applied 

 directly to the potato crop, it is better spread in the pre- 

 vious fall or winter than just before plowing. The manure- 

 spreader does better work than hand-spreading because of 

 the practical impossibility of getting as even distribution 

 with a fork as wdth the machine. Unless the potato- 

 grower has only a small area, it is more profitable to give 

 the whole a thin coat of manure than to have parts heavily 

 covered and the remainder without any. Experiments 

 extending over many years show that the profit to a ton 

 decreases as the size of .the application increases. The 

 manure-spreader has an advantage over hand-spreading 

 in this respect because smaller amounts to the acre can be 

 spread evenly. 



The value of farm manure is greatly reduced by poor 

 methods of handling. The best net returns from its use 

 come from spreading as soon as possible after it is made. 

 When necessary to keep it for some time, as when fields 

 are occupied by growing crops in summer, precautions 

 should be taken to prevent loss. Exposure to rains may 

 leach away half the value in a short time. By heating in 

 piles, much of the nitrogen escapes. Keeping under cover 

 prevents leaching. Keeping in shallow^ piles, tramping by 

 animals and occasional wetting prevents heating. Land 

 plaster and other substances are mixed with the manure 

 to prevent the loss of nitrogen. Raw rock phosphate 

 or " floats " is valuable for this purpose in addition to 



