CAMBRIDGE, Mass.
Jodi Hilton for The New York Times
Mr. Fleisher at the university facility where compost tea is brewed.
Jodi Hilton for The New York Times
Kieran Clyne, a Harvard horticulturist, sprays compost tea on the gardens of Treadwell-Sparks House, the residence of the Rev. Peter J. Gomes.
Ben Wolfe
A microscopic image of roots from an oak tree on Harvard Yard.
Mr. Fleisher handed the spade to Kieran Clyne, the horticulturist in charge of making compost at the Arnold Arboretum, an arm of the university, as well as brewing vats of compost tea in a Harvard-owned garage.
When the project started, Mr. Fleisher said, “the soil was so compacted, we could not dig past three inches.”
But when Mr. Clyne stepped down on his spade this day, it went through the grass like the proverbial knife through butter. He made a core sample, a square of turf and soil as wide and deep as his spade, then lifted it gently and laid it on the grass. The soil was dark and crumbly; the roots were six to eight inches long.
Lifting the core sample by its grassy top, he showed how the soil clung to the roots, another effect of all that microbial activity.
Healthy soil is a mixture of sand, silt and clay particles held together by the gums and gels formed by bacteria as well as by fungi and plant roots. These micro-organisms, as well as insects and earthworms, create the spaces through which air and water can trickle.
The test plot’s new ability to absorb and hold water (thus reducing irrigation needs), coupled with the benefits of composting 500 tons of grass clippings, pruned branches, leaves and other material that was trucked off campus to the tune of $35,000 a year, quickly convinced Mr. Carbone that the program should be expanded.
“Now we’re composting all that organic material at the Arnold Arboretum, so we don’t have to pay someone else to truck it out,” he said. “And we don’t have to buy compost or fertilizers, so we’re saving an additional $10,000 in those materials.”
Organic growing techniques are so simple that any homeowner can get the hang of them. But to do so, it’s necessary to learn some basic facts about the structure and biology of your particular soil. In an organic approach, one bag of chemicals does not fit all. And timing is key.
The first step, Mr. Fleisher said, is to take a core sample of your soil, and send some of it to a good testing laboratory, such as the one at the University of Massachusetts, or one recommended by your state university. A textural analysis will indicate the percentage of clay, silt and sand in your soil, and how well it drains. A complete nutrient analysis will tell you what elements and micronutrients the soil contains. Such tests cost from $13 to $75, and results are returned within a few weeks.
The next step is to do a simple percolation test. Use a shovel or a post-hole digger to make a hole 12 inches deep.
“Make one-inch markings on a stick and put that in the hole,” Mr. Clyne said.
Then fill the hole with water and let it drain for 30 minutes. “Then, fill up the hole again, and see how fast it drains,” he said.
One inch an hour is adequate for a home lawn.
Without good drainage, water and air cannot be properly absorbed by plant roots.
Also, “compaction wreaks havoc on your fungal communities,” Mr. Clyne said. And fungi are key to soil health.
There’s a give-and-take between fungi and plants, as the fungi consume carbohydrates exuded by plant roots and give back water, phosphorus and other minerals. Bacteria also consume carbohydrates. And they in turn are eaten by protozoa and other creatures that convert the bacteria’s protein into nitrogen, which feeds the plants.
Adding compost to soil gets that biological community cooking.
“Once you get that nutrient cycling system going,” Mr. Fleisher said, “it can produce 150 pounds of nitrogen an acre. With that kind of available nitrogen, why would you fertilize?”
Not everyone is repeating the mantra “green is the new crimson.”
“I don’t approve of that at all,” said the Rev. Peter J. Gomes as he stood in the front yard of his residence, Treadwell-Sparks House, where a little sign near the viburnum hedge announced that it was part of one of Harvard’s organic landscapes. He thinks the motto and the sign are “a lot of nonsense.”
Mr. Gomes, the minister at the school’s Memorial Church since 1970, said he planted most of the trees, shrubs and perennials here “with my own hands.” But he has always left the grass in Harvard’s hands. “As long as it looks good, I don’t want to know,” he said.
But after an enjoyable joust with Mr. Fleisher, who explained that using compost was “mimicking the laws of nature,” saving water and might even revive the rather spindly hedge, Mr. Gomes put down his sword, sort of.
“Anything that would make this a lush garden, “he said, “I’ll do it.”
To help laypeople unravel the mysteries of the soil in their own yard, Harvard has posted a kind of mini-course on its Web site www.uos.harvard.edu/fmo/landscape/organiclandscaping. It includes simple directions for building a compost pile hot enough to eat weed seeds, building a compost tea brewer, and brewing teas particularly suited for grass, perennials or woody plants.
Previous Article May 2009
Organic brew puts green back into Yard
Eight-month soil restoration project begins to take root
By Corydon Ireland
Harvard horticulturist Kieran V. Clyne uses a tractor and a tank in Harvard Yard to spray grass with custom-made compost ‘teas.’
Earth Week is a good time to celebrate earth itself — the planet’s loose covering of fine-ground ancient rock we call soil.
In its healthiest state, soil teems invisibly with a busy living web of water, gases, insects, bacteria, and fungi.
In the right balance, these interacting biological and chemical components enrich soils, which in turn support healthy plants.
“The amount of life underneath the surface of the soil is amazing,” said horticulturist Eric T. Fleisher, a Loeb Fellow last year at Harvard’s Graduate School of Design (GSD) and a soils restoration consultant at the University this year. “Yet we rarely focus on soil as a living organism.”
Soils under human care require maintenance that is “adaptive,” he said — meaning flexible, comprehensive, sensitive, and complex. Last year, his holistic view (and expert direction) inspired an eight-month soils restoration project in Harvard Yard.
“It’s not product-based,” said Fleisher about the approach. “It’s knowledge-based.” Just adding chemicals denies the biological, chemical, and structural complexity of soils, he said. Better to study them, care for them — and rest ore them — from the bottom up. In a world of plant care still seduced by the power of single chemicals, landscapers have to embrace the idea that there is “no one single answer,” said Fleisher, and that healthy plants begin with healthy soils. The Harvard project was modeled on Fleisher’s work as director of horticulture at Battery Park City Parks Conservancy in Lower Manhattan. Since 1989, the 37-acre swath along the Hudson River has been New York City’s only fully organic public landscape.
The Harvard soils project of 2008 bloomed into an organic landscaping operation that since last May covers the 16 acres of Harvard Yard and adjoining Tercentenary Theatre.
This spring, more of the University’s landscape footprint was added to the organic column, including the GSD, Harvard Kennedy School, and the Harvard Graduate School of Education.
Behind the greening of the greenery is Harvard’s Facilities Maintenance Operation (FMO), a division of University Operations Services that employs 29 landscapers. FMO maintains most of Harvard’s lawn, shrub, and tree assets.
The soils restoration project, guided by Fleisher, also drew on Michael Van Valkenburgh, Charles Eliot Professor in Practice of Landscape Architecture at GSD; the physical resources and planning office at the Faculty of Arts and Sciences; and New York arborist James Sotillo of Tree Wise Inc.
Organic methods will be used exclusively on FMO-maintained properties within the next two years, said FMO landscape services manager Wayne Carbone.
Last year’s pilot project started in March on an acre of grass and trees between Massachusetts Hall and the Phillips Brooks House. (A control plot was behind Grays Hall.)
Initial soil testing — for biology, texture, and nutrient content — revealed that, in landscape terms, the patient was sick.
Soil compaction just beneath the surface made it hard for root systems to penetrate to rich zones of water and food. Organic matter was low, bacteria levels were high (since their protozoan predators were too few), and healthy fungal colonies barely had a subsurface foothold. (Threadlike fungi hold water close to roots, and provide a nutrient reserve.)
Most telling, the soils beneath the Harvard Yard test area contained only 25 to 50 pounds of nitrogen per acre. (Healthy soils hold about 150 pounds.)
FMO landscapers, with training from Fleisher, amended the soils with custom-made compost “teas.” The rich, dark liquids were brewed in 250-gallon vats fitted with aeration pumps, then sprayed onto needy soils.
“You’re applying something that’s a living material,” said Fleisher – so fresh and ready it has a shelf life of only two hours. The first tea formulations in April last year — 300 gallons worth — encouraged colonies of fungi and increased protozoa. (Protozoa, single-celled animals, eat bacteria and excrete nitrogen near hungry root systems. A million or so are in every teaspoon of healthy soil.)
Over the next two weeks, the test plots were treated with one-time organic growth enhancers, aerated, seeded, and layered with compost.
By May, the test soils were demonstrably healthier by both field and laboratory measures. By September, stunted root systems had stretched out up to 5 inches, the biomass of microorganisms had increased, and nitrogen levels were within a healthy range.
“The results are there,” said Carbone, a 28-year landscaping veteran.
Roots grew fast, but grass grew slowly. Once cut twice a week, it was now cut only once a week.
Deeper roots in healthier soil retain moisture better; irrigation rates dropped to half that of Harvard’s conventionally landscaped plots. At that rate, less watering in Harvard Yard could save more than 2 million gallons of water a year.
Yard soils were once so compact that aerating them was like punching holes in a parking lot, said Carbone. After restoration, it was like poking into butter.
Meanwhile, last year’s test plots turned into living classrooms and soil labs. Fleisher and Carbone trained Harvard landscapers about tea brewing, composting, and sophisticated soil diagnostics.
In October, Arnold Arboretum senior research scientist Peter Del Tredici visited the test plots with a class. Anne Pringle, an assistant professor of organismic and evolutionary biology at Harvard, used soils data in a bioinformatics lab exercise. And Harvard doctoral biology student Benjamin E. Wolfe employed DNA sequencing to study fungal and bacterial diversity in the Harvard soils.
Carbone and others shared news of the project during last October’s Sustainability Week, and last November at a two-day Ivy Plus conference on sustainability. (Harvard is the only Ivy League school with a fully organic maintenance program.)
Another spin-off of the soils project is Harvard’s first large-scale composting operation, now in place at the Harvard Arboretum — a money-saver. Last year alone, trucking landscape waste off-site cost the University $35,000.
The pilot program — including consultants, soil analysis, and contract labor — cost about $40,000. One-time costs for the composting operation, tea brewers, and other soils-restoration gear added another $45,000.
Lessons learned on a large scale at Harvard can be applied on a small scale at home, the experts say. To help, FMO is developing plans for an affordable backyard brewing kit for organic compost tea.