Progress 10/01/99 to 09/30/05
Outputs
Green roofs have been shown to reduce the stormwater runoff from buildings. In order to model the reduced stormwater effect of green roofs, reliable estimates of ET from the CAM plants is required. Greenhouse controlled environmental conditions were used to measure and predict ET from CAM plants during winter and fall/spring regimes, along with climatic parameters including air temperature, wind speed, radiation and humidity during 21-day periods without rain. The planted boxes evapotranspired 28% and 57% more water to the atmosphere than was evaporated from the unplanted boxes for the winter and spring/fall, respectively. ET for a green roof with CAM plants averaged 0.61 mm/d and 1.12 mm/d for each dry day during the winter and spring/fall season, respectively. The original Penman equation and Penman-Monteith ET models explained the observed ET rates very well with crop coefficients of 0.74 in winter and 1.97 in fall/spring.
Impacts
Implementing green roof technology in the United states has many benefits, but stormwater mitigation is the main advantage. We have shown that green roofs can effectively retain and detain more than 50% of stormwater in the mid Atlantic states. Nurseries are now producing green roof plants which are sold in several ways: seeds, cuttings, rooted cuttings, pre-grown mats, and in pre-grown modules. Nurserymen and landscape contractors are the principle installers and maintainers of green roofs. The impact, especially for cities , can save billions of collars in new infrastructure cost required to deal with stormwater. This technology is an environmentally sound solution that will save infrastructure costs, and create jobs.
Publications
- Beattie, D. J., Berghage, R. D. and Snodgrass, E. 2005. Plants and Substrates are the Heart of the Green Roof. Proc Int. Plant Prop. Soc. Accepted for Publication.
- DeNardo, J. C., Jarrett, A. R., Manbeck, H. B., Beattie, D. J. and Berghage, D. D. 2005. Stormwater mitigation and surface temperature reduction by green roofs. Transactions of ASAE 48(4): 1491-1496.
- Phillips, J. D. 2005. Assessing Consumer Preference for Value-Added Horticultural Products. M.S. Thesis. The Pennsylvania State University, University Park, PA, 106 pp.
- Thuring, C. E. 2005. Green Roof Plant Responses to Different Media and Depths when Exposed to Drought. M.S. Thesis. The Pennsylvania State University, University Park, PA, 96 pp.
- Wehry, R. H., Kelley, K. M., Berghage, R. D. and Sellmer, J. C. 2005. Using intercept and telephone survey methods to assess consumer awareness and purchasing of Pennsylvania gardener selects, HortTechnology 15 (1): 157-163.
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Progress 01/01/04 to 12/31/04
Outputs
In the protected environment of the greenhouse, eight one square meter model green roofs have been constructed using an expanded clay-based medium that was 8.75cm deep. Each box was hung from a load cell and connected to a date logger, thus became a lysimeter. Four boxes were vegetated with Sedum album and Delosperma nubigenum, and four boxes remained unvegetated with just substrate. The objective of this research is to develop a highly accurate transpirational model that can be applied to larger scale greenroofs in outdoor environments. Data have shown that our lysimeters are able to reliably measure water loss of 100g or less which is the equivalent of .5mm of rain. In addition, they show good agreement among replicates. To date, 4 sets of dry-down data have been collected over periods of 1-3 weeks and are currently being analyzed. Data are being fit to basic ET water loss equations. Data clearly show the plant contribution of water storage and water loss and allow
independent analysis of evaporation, transpiration, and evapo-transpiration under a variety of environmental conditions. We soon will be able to accurately quantify the plant contribution to the system. Additional boxes are being constructed to allow establishment of other plant species for evaluation when the current series of tests are complete. In this way we can establish the relative efficiency of different plant taxa.
Impacts
The impact of this research is that the development of predictive models of green roof storm water retention and detention based o this research will allow engineers and architects to accurately predict the capabilities of greenroofs based on location, plant type, substrate depth, as well as a number of other environmental factors.
Publications
- No publications reported this period
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Progress 01/01/03 to 12/31/03
Outputs
As North America becomes more developed, increasingly large areas of land are being covered with impervious surfaces including buildings, roads, and parking lots. When storms occur, runoff from these impervious surfaces can overwhelm natural and man-made drainage systems with contaminated water that can pose a significant threat to watersheds locally and regionally. Six small (2x2.66M) buildings were placed at the Penn State University Horticulture Research Center in Rock Springs, PA. Three buildings had asphalt roofs and 3 were fitted with extensive green roofs. The slope of all roofs was 8.33% (1:12), and the buildings were oriented north-south with the slope facing south. The green roofs consisted of 76mm of an expanded, clay-based mineral (Garik Corp., Pittsburgh, PA), similar to that used in light weight concrete construction, placed on top of a 20mm drainage layer (Enkadrain 9615, Colbond, Enka, NC). Thus the total roof profile was 96mm deep. The green roofs
were vegetated mainly with Sedum spurium with some Sedum album and Delosperma nubigenum and, after 1 year, covered 90-100% of the surface. All buildings had gutters that were enclosed and connected to runoff barrels (capacity 208L) fitted with pressure transducers (Omega PX26Series, 0.2% of 6.89kPa(1psi)) to measure runoff. Pressure transducers were connected to a Campbell 23X data logger (Campbell Instruments, Logan, UT). Data were collected every min and averaged every 5 min. Buildings were insulated with 76mm of household fiberglass insulation on all sides. Paneling (6.25mm thick) was placed on all interior surfaces, over the insulation. Buildings were equipped with space heaters (1kW)) and air conditioners (3kW). Water quality was determined by analyzing a composite sample for several selected rain events from each building from October, 2000 to June, 2003. Samples were analyzed for several environmental parameters including pH, turbidity, and nitrates. pH was measured using a
Hanna Instruments model HI9813, nitrate was measured using a HACH DR890 colorimeter using the cadmium reduction method (Method 8039), color was measured using HACH DR890 colorimeter using an APHA Platinum-Cobalt method (Method 8025). Turbidity was measured with a HACH pocket turbimeter model 52600-00. A weather station (Watchdog model 500, Spectrum Technologies, Plainfield, IL) sited atop one of the buildings provided rainfall, temperature, solar radiation, and wind data.
Impacts
Typical runoff data were recorded for all rain events in June, 2003. A rain event was recorded when rainfall was in excess of .25mm, was preceded and followed by a 6-hour rain-free period. Total rainfall for 13 recorded events was 107.95mm. Of this amount 52.04mm was retained on the green roof. The 48% cumulative total retained either in the medium or taken up by the plants. Of the 13 rain events during June, 10 produced runoff from the non-green roof, but there were only 7 events that produced runoff from the green roofs. The remaining 6 events involving the green roofs resulted in 100% retention, no runoff. The green roofs were also effective in reducing peak runoff. For example, 25mm of rain were recorded on 17 June. The peak rainfall rate was 2.29mm/5 min, but was only 1.07 mm/5min from the green roof. Similarly, there was a long detention time from the green roofs where runoff was not recorded until nearly 6 hours after runoff was initiated from the non-green
roofs. This rain event was preceded by a 71 hour rain-free period. Green roofs retain water that will be evaporated or transpired back to the atmosphere and slow down or detain runoff so storm water may not overwhelm storm water systems. Of course the ability to retain and detain storm water are influenced by the physical and biological properties of the system. The water holding capacity at the start of the rain event, the intensity of the rain event, evapotranspiration, and plant water uptake and storage will all influence the green roof for any specific rain event.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
Phase I: On May 23, sedum plugs (72's that were 1.5 inches wide x 3 inches deep) were planted into circular pots in a highly porous, expanded clay-based medium (dry bulk density = 42lbs/cubic ft.) suitable for green roofs. Pot dimensions were 14 inches wide and 5 inches deep and were originally designed as hanging basket containers. After the plugs were transplanted planted, each pot received 10 g of surface applied Osmocote 14-14-14 and were watered in. Plant varieties are as follows: Delosperma aberdeenense, Delosperma nubigium, `Basutoland', Sedum acre `Aureum', Sedum album, Sedum album `Murale', Sedum floriferum `Weinenstephaner Gold', Sedum reflexum, Sedum sexangulare, Sedum spurium `Fuldaglut, `Sedum spurium `Roseum'. There were 10 plant varieties, each with 3 replicates. Pots were arranged in a completely randomized experimental design. On May 20, and at 2-week intervals each pot will be photographed. Photos were transferred to Adobe Photoshop, sized, printed,
and the outline of each plant cut out and weighed to determine a relative growth rate for each taxon. Phase II: On 20 September 2002 all pots were moved into a Penn State Horticulture Department greenhouse for controlled drought stress. Initially, all pots were brought up to pot (field) capacity. Then, every pot was weighed daily for 19 days. At the end of this cycle, all pots were immersed in water until fully saturated, drained for 3 hours, then re-weighed. Twenty four hours later pots were again immersed, drained for 3 hours and weighed. Pots were then weighed daily for 19 days and the saturation procedure described above was repeated.
Impacts
Growth data remain to be analyzed. Drought stress data suggest that sedum and delosperma plants can store as mush as 30 percent of the saturated capacity of the green roof medium.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Forsythia x 'Meadowlark', and daylily 'Catherine Woodbury' were used to evaluate the plantability of 2.3 L untreated and Cu-treated (2400 mg Cu/ kg fiber dry mass (DM)) fiber pots that had either slit or hole wall openings. Slit and hole wall openings of equal area (2.85 cm2) were either 3 or 6. Plants of each taxon were planted, with the pot remaining on the rootball, into either a Hagerstown silty clay loam field for 17 and 63 wks or into a 10.8 L plastic pot for 14 and 52 wks (Repot-in-a-Pot trial). Irrespective of trial and taxon, planted untreated fiber pots decomposed or softened quickly; however Cu-treated pots (CTP) did not. Roots grew profusely through untreated pot (UP) walls, but not through CTP walls where root growth was exclusively through wall openings. In the field trial, forsythia rooted through CTP openings the fastest. At 17 and 63 wks, 44 % and 43 % fewer forsythia large roots exited CTP than UP. Avg shoot dry mass of forsythia in CTP was
significantly less than UP at 17 wks, but not at 63 wks. At 17 and 63 wks, 90 % and 92 % fewer large daylily roots exited from UP than CTP. Avg shoot dry mass of daylily in UP and CTP differed significantly at both harvests. Among the wall opening treatments of CTP, both taxa exhibited a trend of increasing shoot dry mass and number of larger roots with increasing number of wall openings. Irrespective of taxon, the avg number of large roots the Cu-treated control pots (having only drainage holes) frequently differed from the 6 hole and 6 slit treatment and less frequently differed significantly from the 3 hole and 3 slit treatment. Avg shoot dry of forsythia, in contrast to daylily, did not differ among the wall opening treatments of CTP. In the Repot-in-a-Pot pot experiment, at 14 and 52 wks, forsythia CTP avgd 63% and 65% fewer large roots and had avg root dry mass outside fiber pots that avgd 27% and 25% less than forsythia in untreated fiber pots. Avg shoot dry mass did not differ
between forsythia in CTP and UP at 14 wks (shoot dry mass at 52 wks missing). Similarly, at both harvests daylily in CTP avgd 72% and 80% fewer large roots and had avg root dry mass outside fiber pots that avgd 68% and 83% less than daylily in untreated fiber pots. Similar to forsythia, differences in avg shoot dry weights of daylily CTP were not significant at 14 wks; however they were significantly different at 52 wks. Both taxa in CTP exhibited trends of increasing avg number of large roots and root and shoot dry mass as the number of wall openings increased. At both harvets the avg number of daylily and forsythia large roots exiting the Cu-treated control pot (drainage holes only) had significantly fewer roots than 75% of the slit and hole wall opening treatments of the CTP. At 14 wks, avg daylily or forsythia root dry mass outside of the control pots were significantly less than the 6 slit and 6 hole treatment of CTP. At 52 wks, these differences remained for daylily, but not
forsythia. With one exception, avg shoot dry weights did not differ among the wall opening treatments at 14 wks for forsythia and at both harvests for daylily.
Impacts
The impact of this research is two fold. First, that Henry Molded Products of Lebanon (manufacturer of the fiber pots) will become more competitive and have greater market share. Second, landscapers will be able to plant directly into the landscape without pot removal. This will eliminate the cost of taking plastic pots to landfills.
Publications
- No publications reported this period
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Progress 01/01/00 to 12/31/00
Outputs
In the Spring, 2000 we began a series of trials to determine if the fiber pots with holes can be planted, and how this technology might be used by nurserymen and landscapers. The experiment compared untreated (without copper amendment) containers with copper treated pots containing only drainage holes, circular holes, or vertical slits. We compared top growth and root growth of Hemerocallis `Catherine Woodbury' with Forsythia x `Meadowlark'. Greenhouse established plants were moved outdoors in late May where plants with their pots were either transplanted to the soil or were potted into plastic containers. One half of each plant taxon fro both the field-grown and the container-grown plants was harvested in September, while the remainder will be harvested in 2001. To compare treatments, we measured top growth, pot strength, and the mass of roots that came through all pot openings. Field-grown pots were dug to include roots 10 cm beyond the pot wall. The dirt was then
washed from the roots so the root mass could be measured. For container-grown plants, the original fiber pot and all roots were separated from the planting medium outside the pot by washing. This report includes preliminary results for the Fall 2000 harvest. General results: No pot treatment had any effect on above ground plant mass of either forsythia or daylily after one growing season After one growing season, all untreated pots -field or container- were 50-75% disintegrated, so these pots had little effect on roots entering the surrounding soil or growing medium Among the copper treated pots, there was little difference in pot strength as measured by a Compact Gauge penetrometer (Dillon, Fairmont, MN) All copper treated pots were extremely soft, but were still intact. Although pot side walls were soft, roots did not penetrate the pot side wall, rather, they exited openings. Although numerical data were not available at this time, it did appear that more roots exited the pot if
more openings were provided. In addition, it appeared that more roots exited slits than holes, perhaps because of the tendency for roots to explore the growing medium in a circular pattern. In summary, it appears that pots can be successfully planted either to the landscape or to the next growing environment. Short-term crops need not have any copper incorporated into the matrix. However, if the pots are to be grown for several months or a season above ground, then copper must be used in the fiber to insure long pot life and holes should be provided to facilitate the rapid exit roots from the pot when planted in the next growing environment. Further data collection from this harvest and results from the 2001 harvest should confirm these observations.
Impacts
Landscape plants are being produced as liners in copper treated fiber containers, containing holes (in addition to drainage holes). These plants can then be planted directly to succeeding production systems, or to the landscape where they will establish and grow normally, while the pot disintegrates. This allows handlers to save on labor costs. It also prevents the plastic pots from being disposed in landfills.
Publications
- No publications reported this period
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