6 CIRCULAR 62 5, U. S. DEPARTMENT OF AGRICULTURE 



for hard seed. The available information on hard seed is very limited. 

 Germination tests of a number of commercial samples show as high 

 as 56 percent of hard seed in birdsfoot trefoil, and it is evident that 

 unless specifically scarified about half the seed or more will be hard. 

 Under favorable storage conditions both birdsfoot trefoil and big 

 trefoil retain then viability through a long term of years. Turner 

 (10) reports big trefoil seed germinating 9.6 percent after a lapse of 

 81 years. 



SOURCE OF SEED 



Seed of birdsfoot trefoil has been harvested in limited quantity in 

 eastern New York for the past few years, and a small acreage was 

 harvested in 1940 in western Oregon and northwestern California, 

 No seed of big trefoil has been harvested in the United States. In 

 New Zealand, France, Italy, Hungary, Denmark, and Germany, 

 and probably other European countries, one or both of these species 

 have been grown in a limited way and seed harvested. Big trefoil 

 seed has been produced in New Zealand, Germany, Italy, France, 

 and probably other European countries. 



INOCULATION 



In districts where birdsfoot trefoil is occurring naturalized, the 

 plants seem to be well inoculated. Experimental trials, however, 

 have shown that the plants do not become inoculated under all con- 

 ditions, and that artificial inoculation is frequently needed. It is 

 recommended, therefore, that artificial inoculation be given to all 

 new seedings. 



FERTILIZER AND LIME NEEDS 



The sections in the United States where birdsfoot trefoil has come 

 into use are more or less deficient in lime, indicating that soils low 

 in this compound can produce the crop satisfactorily. The experience 

 in European countries bears out this conclusion and supports the 

 belief that this crop may have a place in at least limited areas where 

 the lime content of the soil is insufficient for most other legume crops. 

 It should be pointed out, however, that although birdsfoot trefoil 

 does well on soils deficient in lime it has been shown that under such 

 conditions the use of this amendment often is beneficial. It has also 

 been demonstrated that superphosphate and potash are beneficial. 

 Robinson (7, p. 277) in the Empire Journal of Experimental Agri- 

 culture writes as follows: 



The success of the crop depends to a considerable extent upon the supplies of 

 potash and phosphates in the soil. Given a sufficiency of these two plant-foods 

 the crop is capable of yielding well for a long time, periods of 9-20 years being 

 not uncommon. 



GROWING IN MIXTURES 



In many cases it is desirable to grow birdsfoot and big trefoil in 

 mixtures rather than in pure stands. Most growers have followed 

 this practice and except when seed is the main interest it is highly 

 satisfactory. In pastures a mixture is to be preferred, and for hay 



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