34 Farmyard Manure. 



the same drainings with 4000 grains of distilled water, and 

 leaving this more dilute liquid in contact for 24 hours with 2000 

 grains of the same soil and 2000 of subsoil. 



The filtered liquid contained in the gallon : 



Ammonia 6-91 



Organic matters 118*50 



Mineral matters 147'36 



Total amount of solid matters in gallon .. 272*77 

 The 147*36 of mineral matters (ash) consisted of 



Silica 2-38 



Phosphates of lime and iron 1*54 



Carbonate of lime 79'72 



magnesia 6*17 



Sulphate of lime 7'92 



Chloride of sodium 18-90 



potassium 26-44 



Carbonate of potash 4*29 



Originally the liquid employed in this experiment contained 

 19-68 grains of ammonia to the gallon. After passing through 

 half its weight of soil it contained only 6*91 grains of ammonia. 

 Consequently 12 '77 were retained by 35,000 grains of soil, and 

 1000 grains of soil absorbed '365 grains of ammonia. 



This result, it will be seen, agrees closely with the first experi- 

 ment, in which undiluted drainings were used, and ascertained 

 that 1000 grains of the same soil absorbed -396 grains of am- 

 monia. 



In both instances it was thus found that rather more than two- 

 thirds of the amount of ammonia present in these drainings in 

 the form of ammoniacal salts were retained by a very limited 

 quantity of soil. 



I have purposely used a large amount of liquid in comparison 

 with that of soil. If, under such conditions, the soil is capable 

 of retaining two-thirds of the whole amount of ammonia present 

 in a liquid like the one examined, it is not too much to expect 

 that no ammonia whatever will be lost in practice by carting 

 manure on the fields in autumn and spreading it at once. 

 The quantity of soluble ammoniacal matters in a heavy dressing 

 of the best dung does not amount to many pounds, and such a 

 quantity, in relation to the weight of the soil ready to take up 

 ammonia from the manure, is so insignificant that the most scru- 

 pulous may rest satisfied that in a soil containing even a small 

 proportion of clay no ammonia will be lost by dressing the fields 

 in autumn. 



Other no less important changes than those referring to the 

 absorption of ammonia will strike the reader to have taken place 

 in these drainings left in contact with the soil. 



