MANURE, YIELD AND SOLUBLE SALTS IN SOILS. 33 



Except in the case of the Janesville Loam, the observations 

 show a remarkably small amount of phosphoric acid recovered 

 from the unmanured soils, lower than is normal to the field 

 conditions, and in view of other data in the table it appears not 

 improbable that the determination for the Janesville Loam 

 may be too high. 



It is clear that there is a general tendency for the amounts 

 of phosphates which may be removed from the soil with water 

 after a contact of 65 days to increase with the amounts of ma- 

 nure added, but the data are too irregular to justify much more 

 being said. On the whole, more has been recovered from the 

 four poorer soils and, therefore, less has been absorbed, than 

 from the four stronger ones, except where 25 tons of manure 

 were added. The next table shows the relations. 



Mean amounts of phosphates recovered from 



The amounts of phosphoric acid recovered from the soils re- 

 ceiving the heaviest dressings are of the same order of value as 

 that recovered from the soil from a set of greenhouse benches, 

 where a still heavier dressing of manure had been applied, "3 

 barrels of soil to one barrel of manure." In this case the 

 benches were fitted early in May and had matured a heavy 

 X5rop of chrysanthemums when the soil was examined on No- 

 vember 1, yielding, at that time, 105 parts per million of dry 

 soil of HPO 4 . 

 3 



