Organic lawn during the wet month of August. photo credit: L. Stiebitz

How is it working? The 2011 growing season has been extreme from hot and dry to wet and soaked. At the moment, though, the conventional and organic lawns all look the same – green.

Learn more about the organic lawn in these past posts.

Listening to the Organic Lawn

Announcing the Organic Lawn Brochure and Blossoming Research Effort

Remediating Compaction on our Organic Lawn

Organic Lawn Consultation with Eric Fleischer

Organic Lawn Care

Massey Burke prepares the site for the construction of the Beardsley Earthen Wall. photo credit: R. Robert

Massey Burke has been teaching and practicing natural building techniques for seven years. She has built homes to park benches from clay soil, straw, and sand. “Most Americans have never lived in anything truly hand-built,” Burke says. “We are so accustomed to stick-frame structures it has come to seem normal. We don’t realize that most of the world does not live this way, that in most other countries people build with whatever is at hand.”

In 2009, Sasha Rabin and Massey Burke founded the company Vertical Clay. Vertical Clay works primarily with clay soils, local biodegradable fibers, aggregate, found and recycled materials employing the techniques of adobe, cob, earthbag, superadobe, straw clay, clay wattle, wattle and daub, earth and lime plasters, earthen floors and certain kinds of bamboo and strawbale construction.

Burke notes the sustainability of earthen construction, remarking that earthen walls weather slowly, don’t burn, can’t be eaten by insects, and can be reused. With an anticipated life of two years, the Beardsley Earthen Wall is located behind Beardsley Hall near the Viburnum Collection.

Professor Syd Carpenter and student volunteer prepare clay for construction of the Beardsley Earthen Wall. photo credit: R. Robert

Massey was invited to construct this distinctive wall by Professor of Studio Art, Syd Carpenter. While over 30 community members, Arboretum volunteers, and students from across campus are helping to “play in the dirt” and construct this earthen wall, Carpenter’s class, entitled The Container as Architecture, have tackled this installation as a class project.

Massey celebrated “I would love to come work on such a project at Swarthmore.  What you propose unifies most of why I practice earthen construction – its capacity for artistic expression, its ability to provide a tangible focus for sustainability dialogue, its interdisciplinary nature and its accessibility to what I call “unconventional work crews (students, volunteers, communities). “

You can see the foundation of the Beardsley Earthen Wall. photo credit: R. Robert

Carpenter commented that the rain has not damped the construction efforts. The rain doesn’t hurt the clay and the volunteers dry out. Come experience the art of natural building at the Scott Arboretum and see a whole new way to get your hands dirty in the garden.

Gardeners, Dwight Darkow and Sue Stark, pose for a whimsical photo. photo credit: D. Mattis

Sue noted, in addition to wildlife benefits, she was interested in plants that establish strongly—that could fill bed spaces, replace lawn, and in particular be an alternative to ivy. In many cases, she gave examples of how the plants have been used around the campus and how they performed.

Here, Sue highlights a few of our birds-and-bees plants, with a focus on ground covers:

Tiarella cordifolia ‘Susquehanna’: This is an example of an ivy replacement. It spreads quickly. Tiarella sp. is said to tolerate a wide range of soil conditions, including alkalinity, which means you can use it near the runoff from a concrete walk or roadway. This is one of the so-called “river series” of foamflower cultivars, named for eastern Pennsylvania rivers. T.c.‘Susquehanna’ is said to have more red in the leaf.

Speaking of ground covers, Waldsteinia ternata, barren strawberry, is also on the sale list. We used the native version, Waldsteinia fragarioides, around the campus as cover under shrubs. Step out of your car in the new Wister Center parking lot and you’ll find it nearby.  Walsteinia also works great with spring bulbs. W. ternata clumps more, doesn’t run out as much as our native, and perhaps can take the heat a little better, but either is an attractive cover.

You have to consider the ‘Gro-low’ cultivar of Rhus aromatic, a worthy native ground cover. We use it on campus near Alice Paul Hall, and it takes off. Bees will be busy around the spring flowers, birds are attracted to the berries, and the red-purple fall color is a delight.

Spigelia Marilandica in bloom. photo credit: Scott Arboretum Archives

Spigelia marilandica is another native perennial worthy of more attention although it is slow to emerge, it’s tough, and has a red flower, which draws the hummingbirds. We use it extensively near the entrance to the Scott Amphitheater.

Red flowers of Aesculus pavia. photo credit: R. Pineo

Also of interest to hummingbirds is the red flower of Aesculus pavia, red buckeye. We have ‘Biltmore Strain’ in the sale. It blooms earlier than the bottlebrush buckeye, Aesculus parviflora, and drives the hummingbirds wild. Whether you consider it a shrub or a tree, it will clump out nicely. You can see it used on campus near the Dana/Hollowell dorms.

Back among the perennials, I’ll mention Phlox paniculata ‘Jeana’ on the sale list. Commonly used, the Phlox flower has the attractiveness and attraction-interest of the non-native Buddleja sp., without the drawbacks. This new cultivar has 2 important virtues: it is very mildew resistant, and does not grow as tall as straight species making it less likely to flop.

Striking yellow flowers of Gelsemium sempervirens 'Margarita'. photo credit: R. Robert

Finally, we should consider a plant that is not listed as an “East-of-the-Mississippi” native—the Gelsemium sempervirens ‘Margarita’. Commonly called Carolina jasmine, this is a U.S. plant, but is found further south and out of our indigenous area. However, this selection has proven hardy up through zone 6. It has very fragrant, yellow, trumpet-shaped flowers that bring in butterflies and hummingbirds. It’s a vine that can be trellised vertically, or grown horizontally along a fence, or as a groundcover. Plus, it is a Pennsylvania Horticultural Society Gold Medal winner.

You can get complete descriptive and cultural information on the plants Sue mentions from the Plant Sale Handbook.

In addition, note the excerpt listings starting at page 53 in the back of the handbook, the “Plant Suggestions for Specific Needs.” Two categories particularly relate to our discussion here—the Native Plant list and the Winged Wonders list (for bird and pollinators). For your convenience, we’ve reprinted each as one-page lists—Natives here and Winged Wonders here. Read about other great wildlife and conservations recommended by Habitat Steward, Barb Elliot.

==================== >< ===================

Ted Patterson, from Wayne, PA, retired from public relations work with the U.S. Dept. of Agriculture, is a co-chair of the woody plant section at the Scott Associates Plant Sale.

Barb Elliot's yard has been a certified wildlife habitat since 1998. photo credit: T. Patterson

We asked Barb Elliot to highlight some plants ideal for our non-human neighbors. Barb is the co-founder of the Backyards for Nature program at the Valley Forge Audubon Society. Active in several Philadelphia-area conservation groups, Barb is a trained “Habitat Steward” by the National Wildlife Federation, and her yard has been a certified wildlife habitat since 1998.

Barb bases her plant selections on a strict interpretation of “native”—giving the highest priority to plants she knows are indigenous to Southeast Pennsylvania and the Piedmont area. As an avid bird-watcher, her comments are a result of many hours of observation of animals and insects. Barb’s recommendations include:

Betula nigra provides shade for the Harry Wood Garden. photo credit: R. Maurer

Betula nigra. I have grown three river birches in my yard. They grow quickly, and serve as great hosts for leaf-eating insects while maintaining an attractive presence in the garden.

The attractive fall color of Cornus florida. photo credit: R. Robert

Everybody knows the flowers of our native dogwood, Cornus florida, but we should also remember the value of the red berries for migrating birds. Dogwoods are hosts for a number of butterfly and moth caterpillars, including spring azure butterflies and the cecropia moth, our largest native moth.

The leaves of Quercus muehlenbergii, the Chinkapin oak, seen here, are said to remind one of the Chestnut (Castanea dentate). However, blight has largely robbed us of seeing Chestnuts. Q. muehlenbergii leaves are also similar to the Chestnut oak (Quercus prinus), but shiny, more narrow, and sharply toothed. Find it at the Scott plant sale, because it is very uncommon in commercial trade. photo credit: T. Patterson

Although I don’t have Quercus muehlenbergii, I do know that everyone should have an oak. Oaks are at the absolute top of Doug Tallamy’s value list—supporting some 534 species of butterfly and moth caterpillars. These insects are a key food source for migrating birds, and offer acorns for birds and other animals. Bird-watchers tell you, “If you want to see spring migrating warblers, look in oaks.”

Most people probably think about Vaccinium, the blueberries, for dessert, but remember it’s a wonderful multi-use native plant. We have a blueberry hedge along our back fence, and tons of bees are among the flowers. The foliage is a food source for several butterfly species. The reality is, whatever our measures, we’re likely going to be sharing those blueberries with the birds. Netting is dangerous to birds—something I won’t do, and I just expect to share.

Juniperus virginiana 'Grey Owl' dabbled in snow. photo credit: J. Coceano

Speaking of berries, I now have eight Juniperus virginiana in my yard. The Eastern red cedar is fabulous cover for birds, plus many species nest in them. Last winter, I found a screech owl roosting in one of my trees. The little blue berries on the females are a significant food source, with some 54 bird species eating the fruit. The plant is also a larval food for the juniper hairstreak butterfly.

Discovering great plants at the Scott Assoicates Plant Sale. photo credit: J. Goren

All of the aforementioned plants will be available at the 2011 Scott Associates Plant Sale. Nearly one-third of the plants offered—both the woody shrubs and trees and the herbaceous perennials—are native to the eastern U.S.

These plants have selected because they are adapted to soil and weather conditions in Delaware County. They are low maintenance, energy-savers—needing less water and fertilizer than many other plants. And more, important, they provide food and shelter for birds, butterflies, pollinators, and other beneficial fauna, which have evolved over millennia expecting the seeds, berries and pollen from these co-inhabitants.

2011 Scott Associates Plant Sale Handbook. photo credit: R. Robert

You can get complete descriptions and cultural information about the plants Barb mentioned from the Plant Sale Handbook.

For a complete list of native plants available see page 53 in back of the handbook. For your convenience, we’ve reprinted it as a one-page list here.

Subscribe to Garden Seeds to read about Barb’s perennial plant recommendations and selection criteria for wildlife and conservation plants in our next post. Read more about planting for birds, insects, and pollinators in the Fall 2011 issue of the Hybrid. Laura Stiebitz discussing how the Scott Arboretum’s Pollinator Garden became a certified wildlife habitat with the National Wildlife Federation.

==================== >< ===================

Barb Elliot, Ph.D. in Educational Psychology, trained as a reading specialist, worked for GE Aerospace, retired from market research at AstraZeneca, and lives in Wayne, PA.

Ted Patterson, from Wayne, PA, retired from public relations work with the U.S. Dept. of Agriculture, is a co-chair of the woody plant section at the 2011 Scott Associates Plant Sale.

Learn more about the organic lawn in these past posts.

Announcing the Organic Lawn Brochure and Blossoming Research Effort

Remediating Compaction on our Organic Lawn

Organic Lawn Consultation with Eric Fleischer

Organic Lawn Care

Here is where our hardy installation crew got a workout hauling heavy buckets of rock to all corners of the roof.  Swarthmore College gardener Bill Costello made many trips up and down the roof’s access ladder helping to load the pallets in the parking lot down below and then unload them on the roof.

This larger stone is used in places where the plants have a harder time growing, for example under the edges of the pitched roof where the water drains.  It is also used along the edges of the roof to prevent material from being blown off in this windier zone.

The majority of the roof is covered with our final layer of material, the growing media. The essential attributes of green roof growing media are: it is lightweight and drains well.  It also must contain some compost to provide nutrients to the plants.  On the Wister Center roof, as on our previous green roofs, we used a growing media called rooflite that is blended in nearby Chester County and delivered to us in large sacks weighing hundreds of pounds. Two of these sacks were lifted by crane and suspended over the roof so that they could be slit open and pushed around to pour the material roughly where we wanted it. The media was then raked around the roof to an even 2-3” depth.

Two weeks later, when work schedules allowed and rain was in the forecast, the stars of the show, the plants, were put to work. We were able to dig several dozen clumps of various species of sedum from our David Kemp green roof as well as harvest a variety of sedum cuttings. This plant material was immediately carried up the ladder to the Wister Center roof and planted or, in the case of the cuttings, evenly strewn over the growing media and watered in.

Now it is up to the plants to do their job of establishing themselves and filling in the bare spaces to create the colorful mosaic of a vegetated roof. We continue to be awed and inspired, as well as educated, by these green roof installations on campus. In addition to the significant ecological services they provide, green roofs are ever-changing kaleidoscopes of life.

The Wister Center green roof has earned a special place in the hearts of arboretum staff because it is the first one we have installed (almost) all by ourselves. Previously the college has employed outside contractors to design and install our green roofs, and we gardeners have served as enthusiastic acolytes and willing apprentices, as well as loyal maintainers. This time, however, we came close to flying solo.

Our co-pilot was Peter Philippi the seasoned green roof guru who designed our Alice Paul and David Kemp roofs. Peter has direct experience with many vegetated roofs including a thirty-year-old green roof in Germany that is still going strong.

Most of our materials needed to come via pallets hooked to the end of the very long arm of a crane.  Local arborist Knight Brothers very generously donated the services of this crane and its operator.

On top of the roof’s waterproof membrane goes a thick blanket of recycled polyester fabric that both protects the waterproof membrane and holds on to moisture.

Next came a drainage layer: thin, stiff plastic sheets with drainage channels molded into them. This was a change from our earlier green roofs, which, for the drainage layer, had used an expanded shale product called Solite that was developed and generously donated by an alumnus of the college.

The plastic drainage sheets were used because, unlike our other roofs, the Wister Center has sections of pitched roof that drain onto the green roof.  We anticipate these pre-molded drainage channels will be more efficient in handling the increased volume and velocity of run-off from these pitched roofs.

On top of the drainage layer is a second, thinner blanket of recycled polyester, acting as a filter to keep particles of growing media from clogging the drainage layer and to retain moisture.

Stay tuned for Part II of the Green Roof installation: a glimpse at the installation of growing media and planting of sedums.

By Erin Curtis, Student Organic Lawn Coordinator

The Arboretum recently achieved another step in the transition to an organic lawn maintenance program for Mertz field. We had a demonstration of the “AERA-vator” aeration machine, which loosens highly compacted soil to induce root growth in plants and facilitate nutrient dispersal in the soil. This is a crucial step included in the protocol from our consultant, Eric T. Fleisher. Before our first batch of compost tea is applied, we need to loosen the soil so that the liquid can penetrate further and facilitate microbial activity deep into the root zone.

Not only does compaction limit the depth of percolation of water and nutrients added by the gardener, but also the natural movement of soil organisms that digest and mix organic matter. Compaction occurs when an outside force compresses soil particles together so that little air space remains underground. Healthy soil consists of about fifty percent air and water, which is necessary for plants adequate access to nutrients. Compaction also physically impedes root growth, which in turn limits the plants ability to soak up water and important nutrients. The grass roots are unable to reach farther into the soil and thus cannot access as large a volume of soil along with the water stored in it.

Foot traffic from Mertz dorm to Sharples dining hall has caused this browning of Mertz field. The compaction of the soil has caused the grass to die and be replaced by weeds. photo credit: E. Curtis

As the picture above shows, many weeds have colonized in the grass of Mertz field. In particular, annual bluegrass, white clover, plantain and dandelions are a problem. The vigor of these species over that of turf grass is usually an indication of soil compaction, as these weeds are adapted to survive and thrive in compacted soil. Without addressing the underlying problem of compaction, however, the prevalence of the weeds cannot be combated. Thus, compaction not only has direct effects on roots and retention of water and nutrients, but it also has indirect effects, including that of invasive weeds outcompeting the desired turf grass species.

Compaction is a significant problem in many fields — but what causes this compaction? The compacting force can come from vehicles, heavy machinery, or even foot traffic. Compaction is a common problem on lawns everywhere, and Mertz field is no exception to this where it is difficult to dig even a small hole in the soil. The field has daily human traffic and was heavily compacted by machinery during the construction of Alice Paul and David Kemp Residence Halls.  The field also served as the main practice field for the Ultimate Frisbee team for years.

To solve the problem of compaction, many school districts, municipalities, and athletic organizations use aeration: a large machine churns long tines into the soil, loosening it and introducing air gaps. Our aerator of choice is the “AERA-vator” from First Products — the same aeration machine used by the Phillies. The tines in the AERA-vator vibrate to fracture the soil both underneath and around the machine rather than simply pulling out a plug of soil; this way, the soil is loosened over a wider area and to a greater depth than the tines actually reach. The aerator previously used, a standard type that pushes down under its own weight and pulls out plugs, cannot penetrate even to the full depth of its tines through soil as dense as ours. An aerator that is able to combat compaction effectively is essential for a successful organic lawn.

The AERA-vator apparatus broke through the soil in Mertz field on a beautiful October day when the field was dry enough to aerate.. The first two attempts had to be rescheduled due to weather — when the soil is too wet after a heavy rain, the aeration can do more damage than good, potentially ripping grass from the soil, and the heavy tractor leaving excessively compacted tracks.

The demonstration of the AERA-vator. photo credit: E. Curtis

The machine arrived by truck and was towed by tractor to Mertz Field. The company representative led a group of staff from Grounds and the Arboretum through a demonstration of the machine. The aeration happens through an apparatus towed by the tractor: a large cylinder with many slender 4” tines that vibrate back and forth as it moves forward across the lawn. While in the soil, these tines move back and forth, fracturing the soil between them, rather than just puncturing holes in the ground.

The AERA-vator was indeed effective at loosening the soil, at least in the first few inches: after a pass with the AERA-vator, the ground was noticeably softer to the step. When the compaction was measured with a penetrometer, a device that measures the resistance from the soil when a probe is inserted, the compaction pressure went from about 13.5 force-pounds to about 10 force-pounds, and the probe sank deeper into the soil before it encountered measurable resistance.

After the field was aerated, we were able to begin the application of compost tea. During the month since the field’s aeration, we have brewed and applied about 500 gallons of compost tea to the five acres. Through the winter and early spring, we will have compost — made from the College’s own garden trimmings and dining hall refuse — sifted and spread thinly over the lawn. The infusion of organic matter will add nutrients and will improve the ability of the underground environment to exchange and retain these nutrients and feed the ecosystem of organisms that the compost tea introduced.

Next spring, we will repeat the aeration process and compost tea application, as well as over seeding with a mixture of vigorous turf grass species. Keep your eyes out for more photos and details in a Hybrid article about the organic lawn project soon!

The Scott Arboretum’s Wister Education Center and Greenhouse which opened last fall, recently received gold LEED certification for new construction from the U.S. Green Building Council. The award – which identifies the Center as a “pioneering example of sustainable design” – is the culmination of an effort that began during the earliest stages of the project.

“I feel a real sense of pride that the educational and horticultural work of the Arboretum is housed in a way that exemplifies beautiful and sustainable design and a sensible use of resources,” says Scott Arboretum Director Claire Sawyers. “While we aim to inspire good gardening efforts at a grassroots, regional level, this building demonstrates the Arboretum and College also aim to inspire careful stewardship of the planet as the ultimate garden.”

View into the Terry Shane Teaching Garden from the Wister Center. photo credit: R. Robert

“I am very pleased to extend my congratulations to Claire and her team for working so diligently to make the Wister Center a model of green design,” adds President Rebecca Chopp. “Our community is increasingly enriched by the excellent work and care that this facility fosters.”

Metasequoia glyptostroboides shingles on the Wister Center. photo credit: R. Robert

Construction and design of the 5,200-square foot structure – including a classroom, exhibit areas, greenhouse, and support space – focused on innovative energy efficient green building techniques. One technique is the reuse of Metasequoia glyptostroboides (dawn redwood) trees that were cut down during the construction of Alice Paul Hall. The harvested trees were made into shingles that were used for almost a third of the Center’s siding. Another  technique involved the use of concrete containing fly ash, a byproduct of coal-fired power plants that is usually dumped in landfills.

Light tubes and fluorescent bulbs line the hallways of the Wister Center. photo credit: R. Robert

The building also uses an energy-efficient lighting system. The design opens the building to daylight as much as possible using large windows and “light tubes” that bring light down through the ceiling. Energy-efficient fluorescent bulbs are controlled by occupancy sensors and a building-wide timing system. A green roof is planned and storm water runoff is directed into a cistern used for watering plants surrounding the building.

Following a full day of soil science education and information exchange with consultant Eric “T” Fleisher, Swarthmore College’s Organic Lawn Care Initiative is one step closer to implementation. As I discussed in my last blog post, I am spending my summer internship helping the Grounds Department and Scott Arboretum transition the five-acre Mertz field into an organic lawn, and Monday, July 12 was a critical day in this process. T’s visit is the first pass toward a feasible and effective detailed program design.

We approached T after hearing about his work on Harvard University’s Soils Restoration Project, upon which our program is roughly based. T is the Director of Horticulture at the 37-acre Battery Park City Parks Conservancy (BPCPC) in lower Manhattan. Since 1989, he has been guiding the organization in the use of sustainable grounds management methods, based on the development of a balanced soil ecology, with an emphasis on composting, water conservation, and the use of non-toxic means of pest and disease control. BPCPC is the only public garden space in New York City to be maintained completely organically.

T presents his lecture “Managing the Environment: An Adaptive Challenge” in the Gillespie Classroom of the Wister Center. photo credit: C. Robertson

T began his Swarthmore visit with a presentation and question and answer session on his experience with organic horticultural practices. It was attended by 35 representatives of our staff, the college Sustainability Committee, the Pennsylvania Horticultural Society, local public gardens, Penn State research and extension centers, and local turf care companies. He explained to the audience that pioneering new techniques for managing environmental systems is an adaptive, rather than technical, challenge. Exploring new sustainable management practices requires philosophical and behavioral changes, moving beyond the established “quick-fix” answers that are effective in 85-90% of situations.

Applied to organic lawn care, an adaptive approach means understanding the turf as an environmental system before making any amendments. To attain this perspective, T spent the afternoon conducting a comprehensive site assessment. We gave him a tour of our compost facilities, showed him where we plan to install two solar-powered compost rotators, our compost tea brewing station, and explained what equipment and resources we own or have access to. Then, similar to what I performed last month, T used a spade to gather more soil samples. This set will be sent to a lab called Soil Foodweb, which specializes in biological content testing. Once the tests establish what microorganisms are already present in our soil and compost, T will help us further develop and modify our composting program (already 80% of the way there!), create the compost tea recipes that will best foster natural nutrient cycles in the soil, and adapt our irrigation, aerating, and mowing practices.

Revitalizing boxwoods in the North End Parks of the Rose Fitzgerald Kennedy Greenway. Top to bottom: late March, applying compost tea, early July. photo credit: T. Fleisher

T successfully uses organic management programs to restore the health of ailing landscapes. When the conventional strategy of adding more water, fertilizers, and pesticides to their dying boxwood hedges proved ineffective, the Kennedy Greenway Conservancy in Boston hired T as a private consultant. He soon discovered that the soil, recently disrupted by construction, had very poor natural nutrient cycling and was therefore unable to retain nutrients and nourish plants. Consequently, the boxwood root systems had weakened. T helped the Greenway Conservancy horticultural staff brew a bacteria- and protozoa-rich compost tea, which they injected into the soil.

Beneficial bacteria incorporate nitrogen into their biomass, preventing it from leaching out of the soil. Protozoa feed on these bacteria, metabolizing their carbon and nitrogen content at a ratio of 30:1. They release excess nitrogen as ammonium (NH₄) waste, a form readily utilized by plants. Their roots, in turn, exude substances that nourish bacterial populations. As the compost tea reestablished this natural nutrient cycle in the Kennedy Greenway Conservancy soil, the shrubs rapidly regained their health. Within two months, Boston enjoyed green, vigorous boxwoods in its newest park.

Gardener Nicole Lewis helps T prepare compost samples for biological content testing. photo credit: C. Robertson

Though T is skilled with advanced monitoring and testing equipment, he maintains that the best diagnostic tools are a spade, a soil corer, and his hands, nose, and eyes. Rubbing dirt from each of the three zones between his fingers and carefully examining its color, T made an estimate of the soil texture (the ratio of sand to silt to clay present) that almost exactly matched the UMass lab results: silt loam in the upper and lower thirds and loam in the middle.

Explaining that a very silty soil is an obstacle to easy infiltration, T was not surprised to hear that our cation exchange capacity (CEC) levels are low. CEC is a measure of the soil’s ability to retain and supply negatively charged nutrients such as calcium, magnesium, and potassium to plant roots. These nutrients cling to finely divided organic matter and clay particles in the soil. The microbes added to the soil in the liquid biological amendment (compost tea) will mitigate the effects of our low CEC by fixing these nutrients in their bodies. If their contribution is still not sufficient, we will add bulk compost to raise the level of organic matter present. The success of both efforts relies entirely on the quality of the compost we produce.

Casey Sclar, Ph.D. Plant Health Care Leader at Longwood Gardens, inspects a handful of compost from Swarthmore’s windrow at the municipal compost facilities. photo credit: C. Robertson

At the municipal compost facility, T and the other turf specialists reached into the middle of the maturing windrows, feeling the heat of the pile and extracting a handful of the rich, decomposing material for closer examination. In order to kill any weed seeds that might be mixed into the compost, the heap needs to be kept at a temperature of over 130º Fahrenheit for at least two weeks. If it strays above 160º, however, or does not receive enough air, anaerobic conditions alter the biodegradation process. The simplest method of detecting anaerobic compost, T taught us, is by smelling it: its hydrogen sulfide byproducts produce a scent similar to rotting eggs.

T, professors, Sustainability Committee members, turf specialists, and staff participate in a round-table discussion over lunch. photo credit: C. Robertson

In addition to discussing the technical details of our program, we also engaged T in a planning session on the study and documentation of our lawn care transition. Several professors and college community members joined us for lunch in a dialogue about prospective research projects, curricular tie-ins, and institutional assimilation. They entered a vigorous discussion about the feasibility and value of a scientifically rigorous approach versus a more qualitative life cycle assessment or demonstrative study. Regardless of which experimental design proves most suitable, we plan on monitoring changes in root development, thatch volume, turf density, soil compaction, irrigation requirements, and nitrates, phosphates, and pH levels in the soil and surface runoff. I will work with other students, faculty, and specialists to develop appropriate and replicable techniques to gather and analyze this data.

Examples of new equipment for the organic lawn project. From top to bottom: an Aeravator, lysimeter and hand pump, and a solar-powered rotary composter.

Based on T’s preliminary feedback and recommendations, the Grounds Department will begin researching and acquiring specific equipment, such as a pump for the compost tea brewer and an Aeravator to fracture deeply compacted soil with thin, vibrating metal tines. Andy Bastian ‘12, an intern with the Engineering Department, is hard at work assembling and modifying the design of two solar powered compost tumblers. Professor Carr Everbach is helping me calibrate and install a set of lysimeters to collect soil water samples to look at nutrient levels at different depths in the soil. By the time T returns in the early fall, our capacity to carry out and monitor an organic lawn care program will be significantly greater!

To learn more about T’s work, consider joining the Arboretum trip to Battery Park City Parks Conservancy on October 6^th or attending his next lecture here at Swarthmore at the Perennial Plants Conference on October 15th.