74 THE MANURE HEAP AND SEWAGE. 



stored in cemented pits, that will prevent loss by draining, and if 

 the excess of the liquid manure is caught in special tanks and 

 frequently spread upon the fields before fermentation has progressed 

 far enough to causejnuch ammoniacal fermentation, the greater 

 part of the ordinary losses may be prevented. In thus storing the 

 manure it should be kept moist by the use of liquid manure, but 

 not allowed to become water soaked. It has recently been shown 

 that the losses from manure may be greatly reduced by spreading 

 fresh manure upon the older manure that has already begun to 

 undergo an active fermentation, probably because the carbonic 

 dioxid evolved in the fermentation of the older portions combines 

 with the ammonia developed from the newer portions, this checking 

 its dissipation. The presence of large amounts of hay in manure 

 makes it difficult to compact and, moreover, furnishes large amounts 

 of fermentable matter that increases nitrogen loss. It is therefore 

 usually unwise to allow much hay or straw to be mixed with solid 

 manure. 



Thus the best methods of protecting manure from loss are: i. 

 The exclusion of air. 2. The regulation of the amount of moisture. 

 3. The separation of the excess of liquid manure from the solid and 

 its distribution upon the soil at frequent intervals. 4. Prevention 

 of loss in liquid manure by leaching. 5. The presence of some 

 already fermenting manure to furnish carbonic dioxid to combine 

 with the ammonia as it is produced. 6. The use of some kind of 

 "litter" to absorb the liquid manure and prevent its loss. 



Constructive Fermentations. In order that the manure may 

 become plant food the end-products of decomposition must be built 

 up into the form of nitrates by nitrification. Nitrification, however, 

 cannot take place in the fresh manure since it contains too large 

 quantities of organic products, which, as we have seen, prevent the 

 growth of nitrifyers. 



Exactly when it begins is a little uncertain, but it appears to 

 start only after the high organic compounds have been almost 

 wholly broken up into ammonia, and the ammonia formed has 

 either united with the acids to form salts or has been dissipated 

 into the air. The oxidation of the ammonia salts into nitrites is 



