LEGUMINOUS PLANTS. 121 



smooth. This prepares the ground, for from 

 four to forty years, for three to five crops per 

 year, so the work may well be done with care. 



As soon as there is no more danger of frost 

 in the spring the alfalfa seed which has been 

 screened to allow, if present, the fine seeds of 

 its worst enemy, the dodder, to pass through 

 (see " Purity of Seeds," Chapter IX) should be 

 drilled in thickly (20 to 25 pounds to the acre) 

 to keep down the weeds. The field may be en- 

 riched occasionally with fertilizers containing 

 lime, potash, and phosphoric acid, but no nitro- 

 genous fertilizer will be needed. 



The stable compost, when feeding alfalfa, 

 makes an excellent fertilizer for surface-feeding 

 crops, as the grasses and grains. 



The weeds should be carefully kept down by 

 reseeding the spots where the stand is poor, 

 and by frequent mowing, if need be, until the 

 alfalfa has reached the third year of its growth, 

 when the root system will have become strongly 

 developed and a good stand may be expected. 



Of all the leguminous plants, alfalfa seems to 

 have the greatest number of points in its favor. 

 It enriches the soil by bringing up from great 

 depths plant-food, and depositing it in its tis- 

 sues near and upon the surface. It, in connec- 

 tion with the infesting bacteria, gets its supply 

 of nitrogen from the air, and stores up large 

 quantities of nitrogenous compounds in its tis- 



