510 ALFALFA FARMING IN AMERICA. 
gen, and we can draw on this freely whenever we 
wish, so long as we have alfalfa growing in well- 
aerated soil, its roots close to limestone and sup- 
plied with phosphorus; but how about the drain of 
phosphorus in 70,000 pounds of living animals? The 
body of a lamb contains about .005 per cent of the 
element phosphorus, more or less, according to its 
fatness. Thus we sell away from the farm each year 
in mutton alone about 350 pounds of phosphorus, 
equivalent to about 800 pounds of phosphoric acid to 
replace which would require the purchase of 5,000 
pounds of 16 per cent acid phosphate. Now we know 
that when we add phosphorus to the soil we do not 
get it all back in the crop; that is impossible, so to 
be on the safe side we ought to purchase, for mak- 
ing up this drain alone, at least five tons of 16 per 
cent acid phosphate per year, or its equivalent in 
some other carrier of phosphorus. And as our farm 
is not as fertile as it would be profitable to make it, 
we decided to apply phosphorus yearly in liberal 
amounts to nearly every acre of land bearing alfalfa. 
There are small areas on the farm where phosphatic 
fertilizers do not show an increase. Ordinarily the 
use of 400 pounds per acre of 16 per cent acid phos- 
phate has given us much more than a ton of hay in- 
crease in yield the vear it has been applied, and far 
stronger and better alfalfa the succeeding year. 
The purchase of Nitrogen.—Thus far we have seen 
little need of more nitrogen than we produce on the 
land. In fact, the nitrogen content of our soils is ap- 
parently far in excess of what it was when we began 
