13 



and straw being dissipated to a very slight extent. As, however, it is 

 only the nitrogen of the liquids that is of mnch value, the fact that that 

 element is comparatively stable in the solids cannot prove a source of 

 much satisfaction to farmers. 



Reference to English Results. 



In concluding this brief summary of a small section of recent Ger- 

 man work I may refer to the light which it throws on some of the re- 

 sults that have been furnished by field experiments in this country. 

 During the past few years agricultural societies, county councils, and 

 colleges have conducted a large number of experiments and demonstra- 

 tions on manuring, and one very conspicuous feature in the results that 

 have been obtained has been the comparative lack of action that has 

 frequently characterised the addition of all kinds of artificial manures to 

 dung. Year after year we, in the North of England, have failed to ob- 

 tain any increase of crop, worthy of practical attention, when artificials 

 were used with dung, and indeed the artificials have sometimes positively 

 depressed the yield. These results have hitherto appeared somewhat 

 inexplicable, and were generally believed to be due to the 

 fact that an average dressing of farmyard manure offered to 

 crops as much nourishment as they could assimilate, and that supple- 

 mentary applications of artificials were therefore inoperative. Now 

 however, a flood of light is let in on the subject, and it is evident that 

 nitrate of soda, for instance, when added to dung fails to act to the ex- 

 tent that might theoretically be expected, for the reason that the denitri- 

 fying organisms so abundant in the dung instantly attack the nitrate of 

 soda and dissipate the nitrogen in the elementary form. And the re- 

 searches of Wagner, Maercker,and others have shown that this loss of ni- 

 trogen is not confined to nitrate of soda, but is also met witn to an almost 

 proportionate extent in sulphate of ammonia and in organic manures. 

 Probably the ammonia first requires to be nitrified, and the organic 

 nitrogen to undergo ammoniacal fermentation and then nitrification, be- 

 fore the bacteria can liberate free nitrogen, but the final result is practi- 

 cally the same in all cases. Hence we have an explanation of the com- 

 parative lack of action that has in many English experiments attended 

 the use of sulphate of ammonia, bone meal, dissolved bones, and other 

 nitrogenous manures when add^d to dung. And not only has it been 

 found that nitrogenous manures fail to act when applied in this way, but 

 precisely similar results have been got with purely phosphatic and pot- 

 assic manures. Here it cannct be a case of volatilisation of free nitro- 

 gen from the artificial manure ; but Wagner's experiments show that the 

 negative results so frequently obtained when mineral manures are added 

 to dung are intimately associated with denitrification. 



It has already been pointed out that the denitrifying action of 

 dung is diminished with age, but it now remains to be shown that 

 certain substances when incorporated with dung have the power of 

 greatly intensifying and prolonging its denitrifying action. The two 

 substances used by Wagner that are of most interest to us are super- 

 phosphate of lime and kainit. In the end of May 1895 a number of 

 cemented pits were filled with 500 kilogrammes of dung (about £ ton), 

 and in certain cases the dung as it was filled in was carefully mixed 



