20 ' The Bulletin. 



all stock off of the alfalfa field during the winter, as there is increased 

 danger to the animals themselves when grazing it after frost. 



ALFALFA AS A SOIL PKOTECTOR AND ENRICHEE. 



It is true that alfalfa, being such a luxuriant grower and large 

 hay producer, draws heavily upon the plant-food resources of the 

 soil ; but, notwithstanding this fact, it is a great soil enricher, if 

 phosphoric acid and potash in available forms are present in or are 

 added to the soil in sufficient quantities to promote its most favorable 

 growth. The enriching of the soil is largely through the following 

 means : 



(1) If the alfalfa is inoculated thoroughly — which is generally 

 evidenced by a healthy luxuriant growth — many pounds of costly 

 nitrogen per acre are each year taken from the atmosphere for the 

 growth of the plants. This nitrogen, contained in the plant structures, 

 will, when the hay is fed, be excreted partly in the urine and drop- 

 pings of the animals, which may go to enrich the alfalfa or some other 

 field with nitrogen and humns — two constituents that are greatly 

 needed in most of our North Carolina soils for the growth of larger 

 crops. 



(2) The roots of the plants, penetrating to great distances in the 

 soil, draw largely for their mineral plant-food constituents from 

 depths that ordinary agricultural plants are not able to reach. It, 

 as it were, gradually and to a slight extent at least, brings some of 

 the latent plant-food resources underneath the soils to the surface 

 for future use. The deeply penetrating habit of its roots also gives 

 alfalfa great resisting power to droughts. 



(3) By the roots penetrating the soil in every direction and 

 finally dying In it, the mechanical condition of the soil and subsoil 

 is greatly improved and a large amount of their inert mineral fer- 

 tilizing constituents are thereby brought into such a condition as to 

 be capable of and suitable for the nutrition of plants growing on the 

 gTound subsequently. A crop of alfalfa is also a great protection 

 against washing of the soil on which it is growing, due to the in- 

 creased holding power of the soil for moisture, and also to the con- 

 stantly interfering and retarding influence of the mass of alfalfa 

 crowns and fallen leaves for any surface-water that may have accu- 

 mulated during an excessive rain. It must not, however, be inferred 

 from the facts given above that alfalfa can be used to improve a poor 

 worn-out soil, for such will not be found to be the case, as it will 

 generally fail to make satisfactory growth on all poor and impover- 

 ished soils. 



When once a good stand of alfalfa has been secured on a field in a 

 fairly good state of fertility, it will frequently grow well for 10 to 15 

 years, or even longer, if proper management and fertilization are 

 given it. 



