28 



Richard H. Boerker 



Table of Soil Moisture Content in Light Cultures in Per Cent. 



Depth 2 cm. 



Soil depth was comparatively easily controlled, either by only 

 partially filling the flats with soil or by using deeper boxes. This 

 was done and the depths used were as follows : 



Shallow soil 4.0 cm. 



Medium deep soil 9.0 cm. 



Very deep soil 30.0 cm. 



The depth of the medium soil was the depth of all the other 

 cultures used in the light, soil moisture, and soil texture experi- 

 ments. No attempt was made to measure the soil moisture con- 

 tent periodically in the soil depth cultures, except as noted in 

 checking up the watering of the cultures. 



Soil moisture was controlled in the soil moisture experiment 

 by watering the cultures at different intervals. The wet culture 

 was watered every evening, the medium wet culture was watered 

 every Wednesday noon and Saturday evening and the dry soil 

 culture was watered only every Saturday evening. The soil 

 samples that were taken were secured just before watering and 

 were taken at first every Wednesday noon and every Saturday 

 evening and later only every Saturday evening. Thus the soil 

 samples represent the minimum water content of the soil at the 

 end of one day, at the end of three and one half days, or at the 

 end of seven days. In the following table are given the soil 

 moisture per cents as taken at various depths according to the 

 stage of development of the majority of the seeds or plants in 

 the cultures concerned. 



