250 ALFALFA FARMING IN AMERICA. 



There is hardly any other plant that will so thor- 

 oughly pump the moisture out of soils as alfalfa. 

 Its roots reach down deep, its leaves transpire a 

 vast amount of water every day. For that reason 

 alfalfa is not usually very beneficial to a young 

 orchard, as it dries out the land too much. The 

 writer has seen a thick stand of Kentucky blue grass 

 so dried out by the alfalfa growing with it (the grass 

 an intruder) that it killed it out, root and branch. 

 This of course is most unusual ; as a rule the grass 

 lives long enough to choke the alfalfa. 



Amount of Water Used. — Unfortunately no one has 

 determined the amount of moisture used by alfalfa 

 in making a pound of dry matter. Taking the red 

 clover plant as a guide we may assume that it re- 

 quires from 400 to 500 pounds of water for each 

 pound of dry matter made. Guessing that it takes 

 450 pounds of water to make one pound of dry mat- 

 ter we reach the conclusion that to grow six tons of 

 alfalfa hay will require about 2,500 tons of water. 

 That is equivalent to about 25 inches of rainfall, if 

 none of it were lost. There is beside a considerable 

 loss by evaporation from the soil. To balance that 

 we know that we have a store of subsoil moisture 

 gathered during the winter and early spring rains. 



Now, the rainfall during the 18 weeks that alfalfa 

 makes its hay crops (in the cornbelt region) is sel- 

 dom more than 18 inches and is often very much less 

 than that. So it is clear that lack of moisture is 

 often the limiting factor in alfalfa growing. For 

 that reason the writer, while he has grown six tons 



