SOILS AND FERTILIZERS 423 



It has been questioned whether the construction of expensive 

 cisterns for collecting the manure leachings repays the cost, but it 

 is obviously desirable from what has been said regarding the value 

 of the liquid manure and the desirability of promoting regular and 

 uniform fermentation of the manure that the leachings should be 

 saved and added to the manure heap by some means. Stored separ 

 rately, the liquid part rapidly deteriorates and the solid part, from 

 lack of moisture, is liable to undergo fire-fanging or harmful fer- 

 mentation. 



The nature and extent of fermentation in manure also depends 

 to some extent on the composition of the manure, more particularly 

 upon the amount of nitrogen in a soluble form which it contains. 

 The greater the amount of soluble nitrogen the more rapid the fer- 

 mentation. Urine, as we have already seen, is rich in soluble nitro- 

 genous compounds, and this explains why it decomposes so rapidly. 



By fermentation manure decreases rapidly in bulk. The sub- 

 stances of which it is composed' are converted largely into water 

 and gases, principally carbon dioxid, and where fermentation is not 

 properly controlled, nitrogen may escape either in the free gaseous 

 state or as ammonia. The coarse materials of the manure are grad- 

 ually decomposed and are dissolved to a considerable extent in the 

 black 'liquid which oozes out of the manure heap. As already shown 

 the mineral matter (phosphates, potash, etc.) is also rendered more 

 soluble. When properly controlled, therefore, fermentation is a 

 valuable means of increasing the availability of the fertilizing con- 

 stituents of manure, although it decreases the bulk; but when not 

 properly controlled it seriously reduces the value of the manure. 



Leaching of Manure. Leaching is the second cause of deterior- 

 ation of manure. When manure is exposed to the action of the ele- 

 ments and the leachings allowed to drain away it rapidly decreases 

 in value. Both the organic and the mineral constituents originally 

 present, or which have been made soluble by fermentation, are car- 

 ried off and lost. Experiments at the New York Cornell Experi- 

 ment Station indicated that horse manure thrown in a loose pile and 

 subjected to the action of the elements will lose nearly one-half of 

 its valuable fertilizing constituents in the course of six months; and 

 that mixed horse and cow manure in a compact mass and so placed 

 that all water falling upon it quickly runs through and off is sub- 

 jected to a considerable, though not so great, loss. 



The Kansas Station concludes from similar observations that 

 farmyard manure must be hauled to the field in spring, otherwise 

 the loss of manure is sure to be very great, the waste in six months 

 amounting to fully one-half of the gross manure and nearly 40 per 

 cent of the nitrogen that it contained. 



In more recent experiments at the New Jersey stations solid 

 cow dung exposed to ordinary leaching for one hundred and nine 

 days lost 37.6 per cent of its nitrogen, 51.9 per cent of its phosphoric 

 acid, and 47.1 per cent of its potash. Mixed dung and urine lost 

 during the same time 51 per cent of its nitrogen, 51.1 per cent of 

 its phosphoric acid, and 61.1 per cent of its potash. In brief, more 



