44 Alfred J. Ewart : 



to perceptibly affect the amount of the water-soluble, and still 

 less of the acid-soluble residues per kilogram. Fluctuations in 

 these of less than 0.02 to 0.01 of a gram appear to be mean- 

 ingless, or, at least, to result from fluctuations or conditions 

 beyo*d control, such as slight differences in the drainaige, in the 

 fineness of the ^oil, and in the slight unevenness in the distri- 

 bution of the vital, physical and meterological conditions which 

 affect it during the period of observation. Even when first ap- 

 plied, and distributed at a depth of 2 inches, the nitrate of soda 

 and ammonium sulphate are barely present in sufficient amount 

 to appreciably affect the soluble extractions from the soil by 

 the method of partial lixiviation (2 litres of water to 1 kilogram) 

 employed. By this method is determined merely the amount 

 of soluble material immediately available for a<bsorption, and 

 which can be readily washed from the soil by rain. The 

 blood manure and superphosphate might be expected to produce 

 a distinct temporary rise of concentration in the superficial 

 layers, whereas the relative insolubility of the star phosphate 

 and bone dust would prevent them from producing any direct 

 effect upon the superficial concentration. In the case of plots 

 2, 3, 5 and 6, any rise of concentration is either the result of a 

 secondary action of the manure on the soil, or to the ascent 

 and concentration by evaporation of the dissolved matter from 

 the deeper layers of the soil. An apparent decrease of concen- 

 tration may represent either an actual loss or a lessened 

 solubility of certain c-onstituents. 



The following table gives the amounts of soluble matter 

 extracted from a kilogram of dry soil by two litres of water, as 

 calculated by the evaporation of one litre of the clear filtrate, 

 the samples of soil taken in May, September, and December of 

 190'6 being tested, and th6se of intermediate months used for 

 control. The manuring took place in the month previous to 

 the taking of the first samples (tiind the planting of the crop), 

 while the last set of soil samples were taken the month alter 

 harvesting : — • 



Plot U- 



