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 year 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 



