9. Used as a mulch for growing greenhouse roses, bark showed outstand- 

 ing possibilities. Yields of rose blooms were considerably greater with two 

 bark mulches than when mulched with cow manure. The bark also lasted 

 lonaer than manure. 



f 



10. Bark as a growing medium for apple seedlings had no influence on 

 infection from scab. This was contrary to a supposition that it might cause 

 immunity. 



11. Shredded bark compared very favorably with sphagnum peat as a 

 packing material for live plants. 



For field plot trials, the four kinds of bark, in comparison to manure and 

 controls without organic matter, were applied in replicated plots. All were 

 fertilized alike. As might be expected from the additional fertility it con- 

 tained (beyond the commercial fertilizer application), manure produced 

 best yields for all five crops tested. However, plants grown in the two kinds 

 of old bark produced considerably higher yields than those in the soil 

 controls in 8 out of a possible 10 cases. Even the new barks gave higher 

 yields than controls with all crops except potatoes. When it is considered 

 that the original soil was practically devoid of nutrients, this shows that 

 bark has considerable potentialities as a soil builder in field use. 



Literature Cited 



1. Baker, J. R., and Dunn, S. Sawdust Composts in Soil Improvement: III. 



Pot Culture Studies with Composts from (a) Outdoor Pits (b) 

 Wooden Bins with High Moisture, (c) Other Mixtures. Plant and 

 Soil 6:113-128. 1955. 



2. Composting for Disposal of Organic Refuse, and Biblography. Techn. 



Bui. 1 and 2, Institute of Eng. Res., Univ. of Calif., 1950. 



3. Dunn, S., Wolfe, L. P. Jr., MacDonald, W. A., and Baker, J. R. 



Field Plot Studies with Sawdust for Soil Improvement. Plant and 

 Soil 4:164-170. 1952. 



4. MacDonald, W. A., and Dunn, S. Sawdust Composts in Soil Improve- 



ment: II. Pot Cultures with Compost Mixtures of Sawdust and 

 Manure, Steam Treated Composts and Miscellaneous Mixtures. 

 Plant and Soil 4:235-247. 1953, 



5. Northeastern Wood Utilization Council Inc., The Chemistry and Utili- 



zation of Bark. Bulletin 25. 1949. 



6. Rettie, J. C, AND Simmons, F. C. Estimates of Bark Supply in the 



Northeast. In Northeastern Wood Utilization Council Bui. 25:7-18. 

 1949. 



7. Wolfe, L. P. Jr., and Dunn, S. Sawdust Composts in Soil Improvement: 



I. Studies on Aeration, Acid Hydrolysis, Manure and Waste Ma- 

 terials as Composting Aids. Plant and Soil 4:223-234. 1953. 



17 



