Alfalfa for New York 1973 



for good growth. In ordinary soils, however, alfalfa is not able to obtain 

 its nitrogen from the soil, but must have the aid of certain bacteria that 

 fix free nitrogen from the air in such form that it can be utilized by the plant. 



Root nodules are found abundantly on the roots during most of the 

 growing season. These nodules are the home of the bacteria that have 

 the power of assimilating free nitrogen from the air in the soil, fixing 

 it in the nodules, and ]jassing it on to the alfalfa plant. 



Where alfalfa has never been grown, the bacteria are probably not 

 present, unless sweet clover is found growing. The proper bacteria may 

 be present in soil to which sweet clover is native; in fact, its presence 

 usualh' indicates a good alfalfa soil. In the absence of sweet clover, 

 bacteria must be introduced artificially. A good method of inoculation 

 is to procure soil from an old alfalfa field and to apph^ it at the rate of 

 from 200 to 300 pounds per acre to the new field just before sowing. The 

 soil shotdd not be allowed to dry before applying. As sweet clover has 

 the same form of bacteria, soil from an old sweet clover patch may also 

 be used with success. An equally good method of inoculation is by 

 means of cultures of the bacteria. There are many prepared cultures on 

 the market, or they can be obtained in limited quantity without charge 

 from the United States Department of Agriculture, Washington, D. C. 

 This College sends cultures to residents of New York State at cost; the 

 charge at present is 25 cents for enough of the culture to inoculate an 

 acre. Persons should address Laboratory of Plant Physiology, College 

 of Agriculture, Ithaca, New York. 



Inoculation is not necessary in limestone soils where alfalfa has been 

 culti\'ated in the neighborhood for many years. Under such conditions 

 the proper bacteria for effecting inoculation seem to be present. Also 

 on very fertile, heavily manured soils alfalfa will often live \\'ithout in- 

 oculation for tw^o or more seasons, when natural inociilation often seems 

 to take place. 



Manuring the land before plowing for alfalfa is a great help, especially 

 in soils on which liming and inoculation are necessar\^ The manure not 

 only furnishes a needed stimulus to the young alfalfa, but, what is more 

 important, it helps to make the soil favorable for the rapid development 

 and spread of the alfalfa bacteria. 



SOWING THE SEED 



Amount of seed 



Twenty pounds per acre is the usual rate of seeding. On good alfalfa 

 land a satisfactory stand sometimes results with from 12 to 15 pounds, but 

 with 20 pounds the stand obtained is oftener too thin than too thick. 



