ALL ABOUT ALFALFA. 235 



by any other plant. It is very rich in phosphoric acid, 

 potash and lime, and gets a goodly portion of nitrogen 

 from the air, leaving much of this in the soil by means 

 of its large roots. Aside from this, when used as a green 

 manure there is a great deal of humus added to the soil, 

 both by the matter turned under and by the roots. The 

 large, long roots open the subsoil to a great depth, serv- 

 ing much the same purpose as the subsoil plow. The 

 writer once saw an alfalfa root at Las Vegas, New Mexico, 

 that measured thirty-two feet in length and had been se- 

 cured by some laborers while digging a well in an old 

 alfalfa patch. When once well rooted a stand of alfalfa 

 seems as impregnable as the gates of Hercules, but a stout 

 and sharp sward plow and four draft horses will turn 

 down the growth at the rate of two or three acres a day 

 if properly handled. 



The extraordinary demand made upon available 

 plant food in the soil by a crop of alfalfa is something 

 not fully comprehended by all growers of the great 

 legume. These demands are especially noticeable in the 

 case of nitrogen and potash, crops often collecting over 

 one-quarter of a ton of each from an acre in a season. 

 It is universally admitted that the mineral constituents 

 of plants, such as phosphoric acid, potash, lime, etc., 

 are derived solely and entirely from the soil. In the 

 case of nitrogen, certain leguminous plants, such as 

 alfalfa, clover and peas, have the power of assimilating 

 large amounts from the atmosphere when sufficient phos- 

 phoric acid, potash, and lime are present in the soil. 

 Therefore, while it is quite possible that alfalfa, being a 

 deep-rooting plant, could secure nitrogen from the soil, 

 the probability that it also secures a large quantity from 

 the air enhances its value as an agricultural plant, firstly, 

 because nitrogen is the basis of the compound protein, 

 the most valuable part of the food product ; and secondly, 

 because nitrogen is the most costly element in all ferti- 



