26 
On the Rain and Drainage'lVaters at Rothamsted. 
calculate what residue of each constituent of the manure should 
be found in the soil, supposing no loss had occurred by drain- 
age. It was found on making the calculation that the phos- 
phoric acid applied as superphosphate was pretty fairly 
accounted for, the excess of phosphoric acid being found stored 
up in the first and second 9 inches of the soil, but chiefly in the 
first. Of the potash applied, a considerable amount was found 
in the soil, chiefly in the first 9 inches, but a large quantity 
remained unaccounted for ; as it was clear that very little had 
escaped in the drainage-water, Hermann Liebig concluded that 
it had been converted into a silicate insoluble in acetic acid. 
Of the sulphuric acid applied, only a small amount was found in 
the soils. Of the soda, no excess was found due to the manures 
applied, save in the soil receiving farmyard-manure. The sul- 
phuric acid and soda, being diffusible bodies, had clearly been 
more or less completely removed in the drainage-water. 
We may obtain evidence of the retention or non-retention by 
the soil or crop ofmanyof the substances applied in the manure, 
by comparing the relative proportion of the constituents present in 
the manure with the relative proportion of the same constituents 
found in the drainage-water ; if no constituent of the manure 
has been abstracted by the soil or crop, we shall find that the 
constituents of the drainage-water bear the same proportion to 
each other as in the manure ; while any assimilation by the crop, or 
retention by the soil, will lower the proportion of the constituents 
thus appropriated in the drainage-water. Thus, taking seven 
plots receiving phosphoric acid, the mean proportion of sulphuric 
acid to phosphoric acid in the manures applied is 1000 : 194 ; but 
in the drainage-water from these plots the proportion is 1000 : 17, 
showing a large retention of the phosphoric acid. Again, taking 
the six plots receiving a full dressing of potash, we find that the 
mean relation of sulphuric acid to potash in the manure is 
1000 : 273 ; while in the drainage-water from these plots the rela- 
tion is 1000 : 50, showing a consumption or retention of more 
than four-fifths of the potash. On the other hand, the relation 
of sulphuric acid to soda in the manure of seven plots is 
1000 : 253 ;* while in the drainage-water the relation stands 
1000 : 271, showing that a little more sulphuric acid than soda 
has been taken up. In the manure of nine plots the relation of 
sulphuric acid to chlorine is 1000 : 367 ; * in the drainage-waters 
therefrom the proportion is 1000 : 382, showing that rather 
more sulphuric acid than chlorine has been retained. Thus 
while the phosphoric acid and potash are largely retained by 
* In making these calculations the estimated amounts of sulphuric acid, 
chlorine, and sotla in the rainfall of the seasons in question, have been added to 
the quantities applied as manure. 
