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Old August 9, 2016   #15
nhardy
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Location: St. Louis
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Here is a story on ground cover here too.

Why landscapers are planting crops on the Arch grounds

From ST. LOUIS POST DISPATCH 3/22/16

• Radishes are rotting on the Gateway Arch grounds.

Crews planted about 400,000 last fall. By the end of October, tufts of bright green had sprouted in unruly rows all over the national park.

They’ve now largely decomposed. But they did what they were supposed to: They sent their thick tap roots almost two feet deep. They froze this winter and died. And they left hundreds of thousands of long, skinny holes in the ground, softening soil that has been compacting for decades.

“It actually feels almost like you’re walking through a forest,” said Arch grounds contractor and arborist James Sotillo, one of the brains behind the plan. “That’s the beauty of these radishes. As they grow, they’re releasing all of these incredible metabolites into the soils".

Much attention has been paid to the biggest components of the $380 million CityArchRiver renovation. The $172 million downtown-facing, glass-and-steel museum. The lid that spans the highway, reconnecting downtown to the park. The nearly 900 London plane trees — some being planted now — to replace the beetle-threatened ash trees.

But designers are also fretting the most unseen of details — the very ground on which all of this grows.

The land under the Arch isn’t particularly fertile. It is largely low-quality clay fill, dumped over the remnants of buildings demolished and left. Officials at the National Park Service and CityArchRiver foundation have said that the old ash trees weren’t going to last much longer, even if the emerald ash borer never reached St. Louis — the soil simply wasn’t fertile enough to support big trees with long lives.

To remedy the problem, Arch grounds contractors have matched compost with the grasses they’re planting, so the right nutrients and organisms are in the ground. They’ve been brewing a special concoction — called a “liquid biological amendment” — and began spraying it every spring and fall before construction even started.

And they’ve spent millions of dollars to buy and truck in tons of new topsoil.

“When you think about ecology, you have to have good soil,” said Susan Trautman, executive director of the regional trails organization Great Rivers Greenway.

Great Rivers is paying for $85 million of the project’s landscaping and trails work, through a sales tax collected in St. Louis and St. Louis County. It has purchased about $5 million in specific soil blends — enough to cover 18 football fields in three feet of dirt — from the Sauget lawn and landscape company Oldcastle.

“Better soil means trees can live longer, develop deeper roots, so they can sustain over time,” Trautman continued.

Contractors planted the radishes in late September.

It was a first for an urban park, several of the Arch landscapers said.

The varietal, called “tillage” radishes, are long and white and burrow deeper into the soil than mechanical aerating, said Adrienne Heflich, a landscape architect with Michael Van Valkenburgh Associates, the project’s lead designer.

Crews, worried about further compacting soil around the Arch reflecting ponds where most of the seeds were dropped, put golf-course turf tires on a small farm tractor.

“Obviously, we didn’t want giant farm equipment ripping around the Arch grounds,” said James Smith, another MVVA architect.

The radishes got off to a slow start, Smith said. But then the rain came and the weather cooled. “We got a lot out of them, a lot more than expected,” he said.

Now, shriveled brown tops still stick out here and there in the grass beside the Arch pathways. They have dug their holes and, as they decompose, are depositing nutrients closer to soil surfaces.

Sotillo called the effort an “unbelievable success.” He said he had convinced New York’s Central Park to do something similar, thanks to the work here. “They were completely sold,” he said.

It’s unclear exactly how much all of this has cost the project upfront. But, in the long term, the architects said, it should save the Park Service money.

Work on the Arch grounds is still scheduled to wrap up in the summer of 2017.

The landscapers figure they can get in one more radish-planting before then.

So expect another round of bright-green tufts and long white roots, coming next fall.
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