704 IOWA DEPARTMENT OF AGRICULTURE 



tively poor soil, have produced what must be considered enormous corn 

 crops in comparison with the average yield for the state. 



Therefore we believe that alfalfa should be plowed up at least at the 

 end of the 5th or 6th year, since with the proper care and management 

 the greatest yields are probably secured during the 2nd, 3rd, 4th, and 5th 

 seasons. 



DURATION OF ALFALFA 



Since alfalfa is a perennial it will grow continuously for many years 

 from one seeding, provided the soil and climatic conditions are favorable. 

 These conditions are ordinarily most likely to be found in the West and 

 Southwest. There is record ot fields in Mexico which have been in al- 

 falfa for over 60 years and probably over 100 years and are now annually 

 producing as good crops as ever. Fields in Montana have continuously 

 produced alfalfa for over 40 years from one seeding. 



But these fields are not all confined to the West, for in South Carolina 

 one field has been cut continuously for 60 years, another in New York has 

 been in alfalfa for 45 years and one in Minnesota for 35 years. 



The virgin soils of Towa were from the beginning given over more 

 uniformly to the production of the special cereal crops, wheat and corn, 

 and as a result the legumes such as alfalfa did not receive general atten- 

 tion here as early as in some other states. But even in Iowa fields have 

 been in alfalfa for over 20 years and one seeding at Burlington has 

 persisted for something like 35 years. 



As a general rule, however, in the humid sections of the country alfalfa 

 makes its best yields during the second, third, fourth and fifth years; 

 and since there is great advantage to be gained by including alfalfa in 

 rotation with other crops, since these crops will be greatly benefited 

 through the increased fertility of the soil, a new field should be seeded 

 down at least every sixth year and the old field plowed up and put to 

 corn. 



VARIETIES OF ALFALFA. 



During many centuries of alfalfa growing in various parts of the 

 world, under widely different conditions, a number of types have natural- 

 ly developed and come to be known as varieties. The uniformity of the 

 plants within any particular type depend more or less upon the length 

 of time the variety was grown in a particular locality, with its particular 

 climate and soil. If the time Vvas long enough the plants became the best 

 adapted to those conditions by a process of natural selection. The longer 

 the time during which this natural selection took place, the more uniform 

 is the resultant progeny. 



We find very great differences in resistance to cold between the dif- 

 ferent varieties or types as well as in their ability to withstand drought. 

 Variations are likewise found in the general habit of growth; the size, 

 form and color of the leaves; the color of the flowers; and the general 

 vigor of the plant. 



Some of the more important regional types generally recognized in 

 the United States today are the Turkestan, the Arabian, the Peruvian, 



