60 



Depth of Sowing Grass and Clover Seeds. [Apr., 



sufficient air at these depths, since the other factors controlling 

 germination were constant for all the tubes. 



The percentage number of seedlings that had reached the 

 surface in 22 days after sowing is given below : — 



I'ercentcuie Surface 

 Depth. Seedlings * 



i in. 65 



i and fin. 75 



^in. 55 



1— Gin 



This experiment shows that red clover seedlings are unable to 

 reach the surface when sown too deeply, and this mainly on 

 account of the large surface which the broad cotyledons offer to 

 the resistance of the soil. When buried at depths of 1 to 4 in. 

 the pressure was so great that the hypocotyls of many seedlings 

 were forced to assume a horizontal position, some being bent 

 right back and forced to grow in the same direction as the 

 radicles. Even at the fairly shallow depths of f to 1 in. the 

 seedlings experienced considerable difficulty in working their 

 way through, as was shown by the very tortuous course followed 

 by the rniich thickened hypocotyls. 



Conclusions. — (1) The best depth at which to sow red clover 

 seeds in lij^ht loamy soils appears to be J to f in.f 



(2) Only a very small percentage of the seedlings may be 

 expected to establish themselves if the seeds are left uncovered. 



(3) Many of the seedlings are unable to reach the surface if 

 the seeds are buried to depths of over an inch. 



(To be concluded.) 



* The soil in the tnhes was pressed very hard, hence the reason for the 

 percentage of surface seedlings being lower than in the pot experiments. 



t cf. Findlay (loc. cit.) who states that he obtained the best results when 

 the seeds were covered by abont ^ in. of soil; he also states that it is 

 necessary to sow the seeds deeper on a dry than on a wet soil. 



