No. 6. 



DEPARTMENT OF AGRICULTURE. 



363 



Regarding the first method it has been shown that denitrification 

 is more active when air was drawn through and over the manure 

 than when it was excluded. 



Under the former condition of free access of air Franke, Gotze and 

 Thurman-' showed a loss of nitrogen amounting to from 27.6 to 42.6 

 per cent, of that originally present. 



Hence to prevent loss of nitrogen the manure should be kept well 

 compacted; its storage in sheds, or even in closed receptacles, where- 

 by it is protected from strong currents of air, is also advisable. 



The preceding authors have also made valuable experiments on the 

 use of preservatives. Of these, the use of super-phosphate is especi- 

 ally recommended. 



In this case the transformation of the nitrogen in the form of free 

 ammonia into free nitrogen was prevented by the use of a sufl8cient 

 amount of the super-phosphate to combine with all the ammonia 

 formed, thus fixing it and preventing its loss. Plaster or sulphate 

 of lime acts in the same wav but less energeticallv. 



The addition of 2-3 per cent, of caustic lime, or 5 per cent, of marl, 

 decidedly reduced the denitrifying power of fresh manure. 



The use of caustic lime, however, is not to be advised as it was 

 found to promote ammoniacal fermentation, and the loss of ammonia. 



According to the authors, the mechanical condition of the manure 

 exerted a more marked effect upon its preservation than chemical 

 preservation. Hence the keeping of the manure in a well compacted 

 condition and free from strong currents of air is of primary conse- 

 quence. 



9. The Disintegration and Dissolution of Mineral Matter. 



This subject has, in a measure, been discussed in previous pages, 

 but a few additional statements, in this connection, might be made. 



The mineral elements of plant food are absorbed in the form of 

 salts. These salts are compounds of acids and bases, as shown in the 

 following list: 



Plants Absorb. 



