426 MISCELLANEOUS FARM SUBJECTS 



great practical importance, for although the use of such manures 

 is almost as old as agriculture itself, there are many questions related 

 to their management and use which have never been clearly under- 

 stood. It is well known that barnyard manure, if neglected, rapidly 

 loses the greater part of its fertilizing value and becomes practically 

 worthless, except to improve the mechanical and physical proper- 

 ties of the soil. It is also well understood by practical men that it 

 is not economical to follow many of the elaborate methods of pres- 

 ervation which have been suggested. To be economical, the method 

 of management must be simple and involve as little labor and ex- 

 pense as possible. The recent studies of scientific men on farm 

 manures have been very largely directed to the very desirable prac- 

 tical end of simplifying methods of management and preservation. 



Since the direct fertilizing value of manure depends so largely 

 upon the nitrogen which it contains, the more important of these 

 investigations have taken into consideration mainly the availability, 

 changes, and causes and prevention of loss of this substance. It 

 has been shown that there is a wide difference between the fertiliz- 

 ing value of the nitrogen of the solid liquid parts of the manure. 

 The effectiveness of the former has been found in experiments to 

 be only 10 per cent of that of nitrate of soda, while the latter was 

 90 per cent, being very nearly equal to that of sulphate of ammonia. 

 The nitrogen of the solid excrement becomes available very slowly 

 in the soil or in the heap, while that of the urine is in a soluble 

 form, rapidly converted into ammonia which may escape into the 

 air. Experiments are recorded which indicate that the effectiveness 

 of the nitrogen of the solid excrement is not materially increased by 

 mixing it with the liquid part, the nitrogen of such a mixture being 

 decidedly less available than that of either nitrate of soda, sulphate 

 of ammonia, or green manures. The conversion of the nitrogen of 

 the urine into ammonia, moreover, is apparently hastened by the 

 admixture of solid excrement and straw. 



Careful attention to the construction of the manure heap so that 

 air will be as completely excluded as possible, keeping the heap 

 moist, and avoiding alternate wetting and drying have been sug- 

 gested as means of preventing loss of valuable fertilizing constitu- 

 ents and of promoting a decomposition which will largely reduce 

 the power of the manure to convert available nitrogen into less 

 valuable or useless forms (denitrifying power) in the soil. Here 

 we have an explanation of the effectiveness of well-rotted manure. 

 Not only is the availability of its own nitrogen increased, but its 

 power to injuriously affect available nitrogen from other sources is 

 reduced. 



Authorities agree that attention to the construction and man- 

 agement of the manure heap is much more important than the use 

 of preservatives, with which the results have been contradictory. 

 Kainit has been found to be effective in checking the formation of 

 ammonia, and superphosphate in preventing its escape. The use 

 of these is to be recommended where they can be cheaply obtained, 

 because, in addition to preserving the manure, they add to it con- 



