324 GRASS MIXTURES SEEDS AND SEEDING 



rubbing over sand paper they will germinate easily. Soaking in 

 commercial sulfuric acid for thirty minutes will also corrode the 

 seed-coat sufficiently so the seed will absorb water and germinate. 



Prom twenty to fifty percentage hard seed is common in new 

 clover seed, but the hard seed's gradually disappear, so that six to 

 eight months after harvest five to ten per cent hard seeds is about 

 normal. The hard seeds are determined by placing a sample to 

 germinate. All that will grow at once will germinate in six to eight 

 days. The rest that show no signs of decay, but appear to be nor- 

 mal seeds, are counted as hard seeds. 



Weed Seeds. Only a few weeds are considered as really dan- 

 gerous to introduce. In grasses, Canada thistle and wild carrot are 

 to be watched for. In the clovers and alfalfa the dodders and buck- 

 horn are most dangerous. In general, seed should not be accepted 

 containing any of these weeds. 



Germination Tests. Germination tests are easy to make, by 

 means of apparatus which has been described (p. 18). These tests 

 should be made where large quantities of seed are to be sown and 

 nothing is known about the quality. 



Actual Value of Seed. In determining the value of seed it is 

 the custom to first separate out the foreign matter, and then make 

 a germination test of the pure seed. Then multiply the per cent 

 purity by per cent of germination to get an actual rating. For 

 example, a certain sample is 95 per cent pure seed which germinates 



