For purity: Allowing "a" to represent the component being con- 

 sidered and "b" the difference between that percentage and 100, according 

 to the following formula : 



( ax b ) 



Pure seed tolerance=0.6 + ( 0.2 x ) 



( 100 ) 



a sample of timothy guaranteed 99.20 would have an allowable variation of 

 .75 or could test as high as 99.95 or as low as 98.45 and be "satisfactory." 



For germination : The following tolerances are applicable : 



Healthy sprouts found by test in each 100 seeds Tolerance 



96 or over 5 



90 or over but less than 96 6 



80 or over but less than 90 7 



70 or over but less than 80 8 



60 or over but less than 70 9 



Less than 60 10 



Therefore, a sample of seed guaranteed 85% for germination may be as 

 high as 92 '^f or as low as 78 '^r and be "satisfactory." 



For weed seeds: The law requires in the labeling of agricultural seed 

 (1) that the percentage of all weed seeds present shall be shown on the 

 tag, (2) that no primary noxious weed seeds shall be present in the sample, 

 and (3) that secondary noxious weed seeds shall be given by name and 

 approximate number, per ounce in groups (A) and (B) and per pound in 

 groups (C) and (D), when present singly or collectively in excess of — 



(A) One seed or bulblet in each 5 grams of Agrostis species, Poa 

 species, Rhodes grass, Bermuda grass, timothy, orchard grass, fescues 

 (except meadow fescue), alsike and white clover, reed canary grass, Dallis 

 grass, and other agricultural seeds of similar size and weight, or mixtures 

 within this group ; 



(B) One seed or bulblet in each 10 grams of ryegrass, meadow 

 fescue, foxtail millet, alfalfa, red clover, sweetclovers, lespedezas, smooth 

 brome, crimson clover, Brassica species, flax, Agropyron species, and other 

 agricultural seeds of similar size and weight, or mixtures within this group, 

 or of this group with ( A) ; 



(C) One seed or bulblet in each 25 grams of proso, Sudan grass and 

 other agricultural seeds of similar size and weight, or mixtures not speci- 

 fied in (A), (B),or (D); 



(D) One seed or bulblet in each 100 grams of wheat, oats, rye, 

 barley, buckwheat, sorghum (except Sudan grass), vetches, and other 

 agricultural seeds of a size and weight similar to or greater than those 

 within this group, or any mixtures within this group. 



Certain tolerances are allowed, however, to provide for variations 

 and unavoidable errors, but only within very narrow limits and for which 

 there is always a standard formula for computation. Examples: (1) Timo- 

 thy guaranteed only 2 per cent weed seeds will not be condemned if it 



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