tiolohh' ('uiistitucnls ill AUarial >io'd. 51 



\voi<iht of residue doubled. The viulues obtained may be taken 

 as [giving the amount of mineral matter in the soil capable 

 for the most part of solution and absorption under exhaustive 

 conditions in from one to several years. 



The acid extracts filtered readily and came throuph quite 

 clear with a single filterino-. This is mainly the result of the 

 coajrulatinp; action of the acid, which, by lowering the surface 

 tension of the finely divided particles, causes them to coalesce 

 and then settle rapidly. To a slight extent it is due to the 

 solution of some of the finer particles, for on adding acid to a 

 turbid water}' filtrate it cleared to a slight extent by solution, 

 the remaining suspended particles then settling. Throughout 

 the following tables the numbers in brackets give the acid 

 soluble less the water-soluble matter. 



May 5 Sept. 25 Dec. 20 



Plot 7— Blood Manure Surface 5.08 (4.44) 4.25 (3.64) 3.68 (8.26) 



(2cwt. per acre) 8 inches 5.74 (5.07) 4.41 (3.81) 3.96 (3.55) 



16 inches 5.64 (5.09) 5.4 (4.84) 3.76 (3.22) 



Avera£?e 5.49 (4.87) 4.69 (4.1) 3.8 (3.34) 



If these figures are reliable, they indicate that blood manure 

 causes a liberation and loss of the reserve plant-food which is 

 altogether out of proportion to the amount removed by the crop. 

 By itself, therefore, blood manure should seem to have a very 

 exhausting action on the soil, and there is no evidence to show 

 that the materials rendered soluble are drawn up to the surface 

 again to any appreciable extent from the deeper layers of the 

 soil. Instead, being mainly nitrates, they readily wash out of 

 it and are lost. 



.May 18 Sept. 25 Dec. 20 



Plot 2— Nitrate of Soda Surface 5.02 (4.54) 4.58 ;^4.29) 5.68 (5.28) 



(1201b. per acre) 8 inches 4.72 (4.3S) 4.50 (4.13) 4.1 (3.69) 



16 inches 4.8 (4.48) 5.02(4.44) 3.68(3.28) 



Aversi>;v 4.84 (4.50) 4.70 (4.29) 4.48 (4.08) 



The fluctuations at different depths might possibly be the 

 result of imperfect sampling, which is ailways of great import- 

 ance, however homogeneous the soil may aippear to be. The 

 averages, however, show a steady decrease. It is always possible 

 that soluble material from one layer may continually diffuse 

 towards another layer in which it is deposited by some kind of 

 chemicajl precipitation, or as a result of evaporation, or the loss 



