for peat and lowest for soil (compost mixture). Records were taken also 

 on the length of flower stalks. The averages were: bark 61.3 cm., peat 77.6 

 cm., and soil 78.2 cm. 



After the final snapdragon harvest, the contents of each bench were steam 

 sterilized without moving them. Four varieties of carnation transplants were 

 installed in equal numbers per bench. The varieties are listed, together with 

 a summary of total yields of flowers in Table 2. Here the greatest total 

 yield was given by the plants growing in the peat mixture, but probably 

 none of the differences is very significant. 



Apparently, in a highly organic compost mixture, such as the basic ma- 

 terial used here, relatively little benefit was secured from additional organic 

 matter such as peat or bark. However, bark might have some advantage in 

 not rotting as quickly as many organic materials now in general use in 

 greenhouse composts. 



In connection with this work on ornamentals, mention may be made of 

 a small experiment on orchids. Three orchid plants were planted in old 

 hardwood bark on January 15, 1952. Nothing else was added. On December 

 15, 1952, these plants appeared to be perfectly healthy, and two of them 

 had produced flowers. Old bark may be regarded as a satisfactory medium 

 for orchid growing. 



Comparative Effects of Bark and Other 

 Wood Wastes on Plant Growth 



Since considerable experimentation has been done with sawdust and other 

 woodwastes (1, 3, 4, 7), it seemed of interest to compare plant growth in 

 bark with several of these. The materials tested in this comparison are listed 

 in Table 3. Ten one-gallon size cans were filled with each material. They 

 were used in the pure state, i.e., no soil was mixed with the organic sub- 

 stances. A good loam potting soil was used as control. At the beginning of 

 the experiment 10 grams of 5-10-10 fertilizer was applied to each can. 



Two crops were grown: cabbage, one plant per can, followed by barley, 

 fifteen plants per can. Between crops the contents of all the cans for each 

 kind of material were re-mixed together and 3.5 grams of fertilizer added 

 per can. The yields, as given in Table 3, show that plants grew much better 



Table 3. Average Dry Weights (Grams) of Two Crops Grown 

 In Waste Bork and Other Woodwastes 



* Mean of yields significantly greater than controls at the 5 percent level. 



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