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8 Arbor Age / June 2014 www.arborage.com said, "but the bubbles in the xylem of swamp white oak are absorbed more quickly." Interestingly, initial results also show that among the diffi cult-to-transplant bur oaks, the smaller the tree, the more quickly any bubbles that form in the xylem are absorbed. UHI will further investigate the role that size plays in transplanting diffi culty. In addition to looking at the size variable, UHI will test the impact of fall vs. spring transplanting, and Bassuk's col- league, Extension Assistant Professor Rick Harper at UMASS- Amherst, is going to look at the effect of transplanting method (B&B vs. bare root vs. container) on cavitation. "This could have great relevance to arborists in terms of guiding plant selection for projects," Bassuk said. "If your client wants 50 tupelo trees at 4-inch caliper, for instance, you can explain, in terms of the mechanism of cavitation, why this is not viable. But from cavitation studies, you'll know that smaller tupelo trees, or those transplanted in a specifi c season, or those grown with a certain transplanting method could make the use of tupelo more successful." Bassuk also wants to explore how production variations in the nursery — such as root ball size and shape — may affect how fast trees recover from cavitation. Stay tuned. Compost precision Every year since 2000, Bassuk's "Creating the Urban Eden" class has taken a piece of the Cornell campus and crafted gar- dens on it. "These are generally former construction sites and other horrible places that look like the face of the moon," she said. As one can imagine, the soil on these sites is compacted to a cement-like state and requires serious remediation. Enter the "Scoop and Dump" technique, in which the compacted soil is scooped up by a backhoe to a depth of 15 to 18 inches, fol- lowed by compost being dumped in among the loosened soil. The amount of compost required to make a signifi cant dif- ference was the research subject of a former student of Bassuk's, Dr. Angie Rivenshield. She found that adding 1/3- to 1/2-by- volume organic matter — or, in the case of these campus sites, 6 to 9 inches — is necessary to signifi cantly reduce bulk den- sity (i.e., reduce compaction) and to increase microorganism populations. Therefore, the "Urban Eden" students would add 6 to 9 inches of organic matter to the site, leaving veins of compost through the profi le of compacted soil. "That's well and good," Bassuk said, "but I always won- dered, how much compost is getting used up?" The gardens looked great, but what was happening in the soil? Though her students always mulched with a shredded hardwood bark and kept the mulch replenished over the years at 2 to 4 inches deep, no further compost was added after the initial "Scoop and Dump" site preparation. Now that there were 13 genera- tions of gardens put in with the same methods, there were 13 sets of soil properties that could be analyzed. Bassuk had theorized that the more recently the "Scoop INDUSTRY INSIGHTS INDUSTRY INSIGHTS One of the 13 Cornell campus gardens that have benefi ted from the simple "Scoop and Dump" method. The roots of swamp white oak, whose xylem is less gravely affected by cavitation than the xylem of bur oak.