CHAPTER IV. 



THE FARMER'S INTEREST IN GOOD SEED, AND 

 HOW TO TEST SEED 



The farmer is especially interested in obtaining seed 

 free from such noxious weeds as Canada thistle, quack 

 grass and dodder. To avoid the introduction of such 

 weeds, the seeds should be examined by the experiment 

 station in the state in which the farmer is located or by 

 the U. S. Dept. of Agriculture. It is customary in the 

 seed laboratory to secure an average sample, thoroughly 

 mixed, of the seed to be examined ; then to weigh out 2 or 5 

 grams and separate out the impurities, such as weed seeds, 

 dirt, chaff, etc. The remaining seed is then weighed and 

 the amount of impurities determined. When a given 

 quantity of weed seed is large this is weighed separately 

 and the per cent of impurity obtained. A more accurate 

 way is to use the table given below. This, method is 

 fairly accurate. We have for a number of years checked 

 these results with those determined by weighing. If the 

 weighing method is used, the analyst gives the total 

 impurities and names those found. 



The following table showing the number of seeds to the 

 gram of various species of weed seeds was compiled by D. 

 C. Snyder and Charlotte M. King in the Botanical Labora- 

 tory of the Iowa state college. To ascertain the number 

 of seeds per pound in any given variety multiply the num- 

 ber per gram by 453-584- 



NUMBER OF SEEDS TO THE GRAM IN WEED SEEDS FOUND AS IMPURITIES IN 

 CLOVER SEED. PREPARED BY D. C. SNYDER AND C. M. KING 



Abutilon Theophrasti (Velvet Leaf) 109 



Acnida tuberculata (Water Hemp) 2,800 



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