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.

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In the fall 2009, a New York Times article about an innovative organic lawn care project at Harvard University shook the assumptions of other higher education institutions regarding their own landscaping practices. A casual inquiry about Swarthmore’s lawn management by an alumnus who had read the piece sparked a flurry of discussion and activity that will culminate this fall in the implementation of the Scott Arboretum’s first organically maintained lawn.

Instead of applying standard synthetic herbicides and fertilizers to the five-acre field between Mertz dormitory and Magill Walk, gardeners will spread compost and spray compost tea. This organic matter will be carefully prepared and monitored to contain a balance of nutrients that fully nourish the soil, the microorganisms that dwell within it and, in turn, the grass. We currently use organic fertilizers and practice integrated pest management as a part of sustainability efforts. This summer we will begin testing organic lawn practices.

Based on favorable results at Harvard, we hope that our new lawn will improve the health of the turf and local ecosystem, minimize environmental impact by reducing mowing and irrigation needs, and offer a cost-saving alternative to conventional lawn care. Since the new approach requires closer monitoring and ongoing program adjustments, labor costs will rise; the cost of purchased supplies, however, will decrease. A project on a New York football field showed that once established, organic lawns can be 25% less expensive to maintain!

“A comparison of costs (dollars) for conventional and natural turf programs over a five-year period, based on data collected and analyzed by Charles Osborne and Doug Wood, Grassroots Environmental Education 2010.”

Next month, Eric T. Fleisher, the coordinator of Harvard’s organic turf program, will visit our campus to tailor his compost tea recipes, application schedules, and aeration techniques to the specific needs of our site.

A rising sophomore and student liaison to the Sustainability Committee this past spring, I received a grant from the Lang Center to work on the lawn care project with Grounds and the Arboretum. My first task was to run the diagnostic tests identifying the present makeup of the soil and turf upon which T. Fleisher will base his recommendations. Using the procedures that he prescribed, I have spent the past few weeks preparing soil samples for lab analysis and conducting percolation tests to determine the rate at which the soil is able to absorb water.

Camille Robertson digging soil samples to send in for laboratory testing. photo credit: N. Lewis

We have to wait for the UMass Amherst Soil Testing Laboratory to get back to us to learn the concentrations of organic matter and extractable nutrients, the soil texture, and the level of soluble salts in the soil, but the percolation tests returned immediate results.

Satellite image of Mertz field taken in 2008 during the construction of David Kemp Residence Hall. photo credit: Google Maps

To account for potential differences among the rates at which water infiltrates into the soil at different depths, I dug three foot-wide holes 6”, 12”, and 18” deep respectively. I then roughed the edges of each hole (so that water enters the soil as “naturally” as possible), lined the bottoms with sand (minimizing splashing, also a potentially confounding factor), and saturated the soil to control for dryness (making tests run the day after a rain comparable to those done in the middle of a drought). After completing these preparations, I filled the holes with water and checked them frequently over the next 12 hours, recording the height of the water column. Noting how quickly the water level drops allows us to infer the porosity of the soil—a more porous soil provides many channels for water, organisms, and roots to pass—an important factor in stormwater retention and turf health.

The 18” hole on Upper Mertz, 15 hours after the percolation test began. photo credit: C. Robertson

A healthy lawn percolates at one to two inches per hour. I conducted the three-hole test in each of three distinct zones of Mertz lawn; only the moist lowermost region drained this quickly. Since the second zone was subject to severe compaction by heavy machinery during the construction of the David Kemp Residence Hall in 2008, percolation rates were especially low there. Water infiltrated at only half an inch per hour. The upper zone, everything uphill of the old laydown area, exhibited intermediate characteristics.

I noticed other differences between the soils in each zone simply by feeling how hard it was to dig (the rocky Middle Mertz required a pickaxe), the general consistency and moistness (Upper Mertz was damper than Middle Mertz but drier than Lower Mertz), and the number and kinds of organisms I came across in the soil (so many earthworms in Lower Mertz!).

Understanding what creates a healthy soil ecosystem is the key to cultivating a thriving green lawn. The results of our diagnostic tests and observations will allow us to design an organic lawn care program that continues our tradition as “the most beautiful campus in the United States.”

Campers from the Chester Children’s Chorus play baseball on Mertz field. photo credit: C. Robertson

Our motivation behind this non-conventional approach lies in the bigger picture—fostering the health of the Crum Creek watershed and its human inhabitants. The college and Arboretum have always strived to be responsible stewards of both by following conventional best practices. But as Rachel Carson taught us, the unintended consequences of one decade’s practices may not become apparent until the next—some health effects of the chemicals we apply could take generations to become apparent, for example. Repercussions of our dependence on petroleum-based products will be magnified when the energy crisis truly sets in. In order to keep our community and environment healthy and sustainable, therefore, we are excited to push forward to tomorrow’s innovation: organic lawns! Check back with Garden Seeds as we describe our progress in developing an organic lawn maintenance program.

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