Sweetgum Hybrids Potential Cash Crop for Marginal Land
While oftentimes considered an undesirable tree in the native landscape, work is being done on a sweetgum hybrid tree to supply the paper and pulp industries in the southeast. Scott Merkle, professor and associate dean of Research at the Warnell School of forestry at the University of Georgia in Athens explains the project:
“There are certainly people that don’t consider sweetgum to be low-value trees at all, in fact, the pulp and paper industry, here in the southeast has mills that use a lot of sweetgum, and their problem is that there are times of the year, mainly the winter, when they need sweetgum fiber for their mills to make paper, and they can’t get enough of it, they can’t get enough of it because places where sweetgum grows are too wet in the winter to go in and harvest.
So, they’re looking for dedicated year-around supplies of sweetgum fiber that they don’t have to drive hundreds of miles to get to feed their mills, and the hybrid sweetgums that we’ve developed are especially suitable for growing in plantations, and landowners, sounds like many of them are very interested in growing the hybrid sweetgums.”
As far as an income stream, forestry is a slow process, quality trees can take up to 20 years to grow into a marketable stand. And encouraging fast growth usually compromises quality. Merkle says, the two situations aren’t mutually exclusive with this sweetgum hybrid:
“At least some preliminary results I’ve seen, you can fertilize a sweetgum all you want and get it growing really fast, and the wood quality, specifically the density, remains about the same. So, you can combine faster growth and higher wood quality in sweetgum. In fact, these hybrids do both of those things; some of the clones actually grow faster than the native sweetgum, and have a higher density than the native sweetgum.”
So, what kind of growth rate are we talking about? Merkle says really fast:
“I would say, and height growth rate of five to six feet a year is pretty fast for a North American hardwood tree. And that’s what you might expect from a really fast growing loblolly pine, as well. So, I think these trees, for North
American trees. Now, compared to a eucalyptus clones that they grow in Brazil, that they’re starting to test and grow in Florida and some other southern states, that’s not fast. But, for North American trees that’s quite fast.”
Merkle outlines what is considered to be a marketable size:
“Probably for the pulp and paper industry, something that is 20-25 feet tall and three or four inches in diameter, that would probably be harvestable. And, as you know when you cut down a sweetgum tree they immediately sprout again, I’d imagine that the sprouts grow even faster than the original seedlings.”
For producers that have marginal land for row crops could consider sweetgums says Merkle:
“I have a small test planting here in Athens at our school forest, Whitehall Forest, and then I’ve visited one test planting on the upper Coastal Plain, near Aiken, South Carolina, and these are sandy soils, they don’t have to be very wet soils. That’s one thing about sweetgums, they’ll grow in any soil, now, if it’s a dryer soil, they’re going to grow more slowly, but I would say any median to wetter site they’re going to grow pretty well, and they’re probably going to probably grow pretty well on drier sites, as well.”
We’ll talk further with University of Georgia’s Scott Merkle tomorrow on Inside Agriculture.