 previous |
Table of Contents | Landscape Clinic | Environmental Studies |  next |
previous |
Table of Contents | Landscape Clinic | Environmental Studies | next |
Appendix H: Calculation of Energy Budget for Lawns and Experimental Plot
Lawns
Values for energy value of gas, water, fertilizer, and biomass of lawn obtained from Robert Perry.
Values for amounts of gas, water, and fertilizer used on lawn and area of lawn obtained from Mike Barber.
Energy input
Gas energy:
900 gal/yr
124,000 Btu/gal = 111,600,000 Btu/yr
Water energy:
Assume 6 months each of winter and summer watering
Gallons of water during summer: 1,083,162 gal/week
Gallons of water during winter: 419,327 gal/week
39,064,714 gal/year
Fertilizer energy (energy to make and apply fertilizer):
3,700 lb. Fertilizer/year
2368 lb. N/year
Total energy input = 552,454,600 Btu/year
Energy stored in biomass of lawn
479,162 ft2 of grass
1197,791 lb biomass
Sustainability
Sustainability = Energy stored in biomass/Energy input
917,000,000 Btu/552,454,600 Btu/year = 1.7 years
Experimental plot
Energy input
Water energy:
9918gal/year (from Appendix D)
Mulch energy
3120 ft2 (area of plot)
Total energy input = 49200 Btu/yr
Energy stored in biomass of plot
This was found by finding the average area of each plant when full grown, assuming they are a circle shape. (A range for the width of the full-grown plant is known. Average radius is taken from the average of the minimum and maximum widths of the plant.). Each plant was then categorized as low shrub (24-30"), medium shrub (30-60"), or high shrub (60-96"). The plants that were taller than 96" were categorized as high shrubs, because they are more shrub-like than tree-like, and the diameter at base height (used to calculate biomass of trees) of these plants, when mature, is not known. The area was multiplied by the biomass (lb/ft2) of the height category for the plant (L = 0.5 lb/ft2, M = 0.75 lb/ft2, H = 1 lb/ft2) and the number of that plant present in the garden. Adding together the numbers for each plant then yields the average biomass of the plot when mature.
* Unknown grass species, assume same as Sisyrinchium bellum
Plant # Height
categorylb/ft2 for
heightRadius
(ft)Area
(ft2)Biomass
(lb)Ceanothus 'Concha' 2 H 1.00 4.00 50.265 100.531 Ceanothus gloriosus 'Anchor Bay' 1 L 0.50 2.50 19.635 9.817 Ceanothus maritimus 'Frosty Dawn' 3 M 0.75 2.25 15.904 35.785 Ceanothus leucodermis 1 H 1.00 2.25 15.904 15.904 Chilopsis linearis 'Red Salada' 1 H 1.00 8.75 240.528 240.528 Dendromecon harfordii 1 H 1.00 6.25 122.718 122.718 Ericameria cuneata 1 M 0.75 2.25 15.904 11.928 Erigeron 'Sea Breeze' 1 L 0.50 0.58 1.057 0.528 Erigeron 'W.R.' 3 L 0.50 0.58 1.057 1.585 Eriogonum umbellatum
var. polyanthum 'Shasta Sulfur'1 L 0.50 2.25 15.904 7.952 Heteromeles arbutifolia 2 H 1.00 8.75 240.528 481.056 Lupinus excubitus var. hallii 1 M 0.75 2.00 12.566 9.428 Mahonia 'Golden Abundance' 4 H 1.00 2.75 23.758 95.033 Mimulus 'Pink Cloud' 1 M 0.75 1.00 3.142 2.356 Mimulus 'Verity White' 1 M 0.75 1.00 3.142 2.356 Nassella cernua 1 M 0.75 1.00 3.142 2.356 Mystery grass (no tag) * 1 L 0.50 0.62 1.227 0.614 Penstemon heterophyllus
var. australis Margarita BOP2 M 0.75 1.25 4.909 7.363 Rhus ovata 1 H 1.00 8.75 240.528 240.528 Salvia 'Allen Chickering' 1 M 0.75 1.50 7.069 5.301 Salvia chamaedryoides 4 M 0.75 1.75 9.621 28.863 Salvia clevelandii 'Winifred Gilman' 2 M 0.75 2.25 15.904 23.856 Salvia greggii 'Furman's Red' 1 M 0.75 1.25 4.909 3.682 Salvia leucophylla 'Amethyst Bluff' 3 H 1.00 2.75 23.758 71.275 Sisyrinchium bellum 2 L 0.50 0.62 1.227 1.227 Trichostema lanatum 2 M 0.75 1.75 9.621 14.432 Zauschneria 'Brilliant Smith' 2 L 0.50 2.00 12.566 12.566 Total average pounds of biomass: 1550 1,550 lb Biomass
7,655 Btu/lb = 11861940 Btu
Sustainability
Sustainability = Energy stored in biomass/Energy input
11861940 Btu/49200 Btu/yr = 240 years
previous |
Table of Contents | Landscape Clinic | Environmental Studies | next |