1. How do chemical fertilizers affect the pH of soil? Erin Flynn December 11, 2003 EDTEP 586

2. Initial Model Soil Miracle-Gro ® pH  3H + Bacteria BAD for plants!

3. Background Information o Liquid Miracle-Gro ® plant food is a source of ammonium and nitrate, essential nutrients for plant growth. o Bacteria in the soil convert ammonium (NH 3 ) to nitrate (NO 3 ). o Excess H + ions in soil cause a decrease in pH. o Changes in pH of the soil can adversely affect the plants that grow in it.

4. Assumptions o The bacteria responsible for the conversion of NH 3 to NO 3 are present and active in all of my soil samples. o The amount of ammonium that was added to the soil samples is enough to disturb the system (i.e. not all H + released in the conversion of NH 3 to NO 3 will be bound to negatively charged organic matter in the soil). o The buffering capacity of the soil samples is negligible. o The amount of time that elapsed through the course of this experiment (3 weeks) is enough time to see a change in pH.

5. Methods November 19, 2003 o Collected soil samples from four Seattle area parks, in areas where plant life tended to be “wild” (i.e. not landscaped, such as wooded areas). o Samples were taken from 6” below the ground surface. o Plants within a 20 ft radius of the dig site were surveyed and catalogued. o Samples were split into 3: first sample was tested for pH immediately; the second and third were incubated at 68°F for three weeks. o 100 ml of sterile water was added to the control sample, and 100 ml of Liquid Miracle-Gro® was added to the experimental sample at a 1:1000 dilution. November 24 & December 2, 2003 o 20 ml of sterile water was added to all samples. December 9, 2003 o pH was tested for all experimental and control samples.

6. How did I test the soil pH? o Used “color pHast ® pH 0-14” strips (EM-Reagents). o Placed a pH strip on the bottom of a 5” plastic pot. o Covered the strip with a 5” diameter filter paper. o Added the soil into the pot. o Poured 100 mL of pre-boiled, room temperature, filtered H 2 O and mixed. o Allowed the water to drain out of the pot. o Inverted the pot, and read the pH strip while still moist.

7. Soil Samples 1: Southwest County Park, Edmonds WA 2: Lincoln Park, West Seattle 3: Carkeek Park, Seattle 4: Discovery Park, Seattle 12 34

8. Data Table DateSite #1Site #2Site #3Site #4Water Control 11/19 C4.05.0 5.55.0 12/9 C4.05.0 5.55.0 12/9 E3.05.03.05.0 pH values of the soil samples at two timepoints. C = control sample (water only added), E = experiment sample (Miracle-Gro ® added).

9. pH change of soil samples pH This chart shows the change in pH values of the four soil samples plus water control over the three week period. E= ammonium added, C = water only added.

10. Why does pH change when ammonium fertilizer is added to the soil? o The conversion of ammonium to nitrate releases three H+ ions. o If there is no buffering agent in the soil to bind to the free H +, it results in a decrease in pH (increase in acidity) of the soil; if there is, the pH will remain unchanged. o If soil is already acidic when ammonium fertilizer is added, denoting a lack of binding materials for free H +, the pH of the soil will only continue to decrease.

11. What is the effect on the plants living in this soil? o When soil is strongly acidic, the bacteria and other microbes that are responsible for the breakdown of organic material in the soil into useful nutrients for the plant are inhibited. o If the pH of the soil is too low, nutrients within the soil may become insoluble, rendering them useless to plants.

12. Plants found at sample sites 1 & 2 Site 1: Southwest County Park, Edmonds, WA o Sword Fern* o Bracken* o Salmonberry* o Red Huckleberry* o Western Hemlock o English Elm* o English Holly Site 2: Lincoln Park, West Seattle, WA o Big Leaf Maple o Low Oregon-Grape o Western Red Cedar o Bracken o Western Hemlock * Denotes species that would be at risk of failure at pH = 3.0 found in experiment

13. Plants found at sample sites 3 & 4 Site 3: Carkeek Park, Seattle, WA o Big Leaf Maple* o Trailing Blackberry* o Salal* o Sword Fern* o Western Red Cedar* o Atlantic Ivy o Low Oregon-Grape* o Red Huckleberry* Site 4: Discovery Park, Seattle, WA o Big Leaf Maple o Lady Fern o Sword Fern o Trailing Blackberry o Atlantic Ivy o Western Red Cedar o Low Oregon-Grape o Western Hemlock * Denotes species that would be at risk of failure at pH = 3.0 found in experiment

14. The Survivors English Holly NON-NATIVE Atlantic Ivy NON-NATIVE Western Hemlock NATIVE

15. Revised Model soil texture Soil organic matter rainfall in health of plants living in this soil Bacteria temperature NH 3 NO 3 soil 3H + soil pH horizon soil type Miracle-Gro ®

16. Fertilizers should be applied with extreme caution!!! o Make sure you test the pH of your soil before adding ANY commercial fertilizer. o Carefully check to see what types of chemicals and nutrients your particular plant food contains. o Do not over-fertilize … more is definitely not better.

17. THANK YOU! o Websites: o http://www.sciam.com/article.cfm?articleID=0009D21B-BDB0-1C72- 9EB7809EC588F2D7&catID=2 http://www.sciam.com/article.cfm?articleID=0009D21B-BDB0-1C72- 9EB7809EC588F2D7&catID=2 o http://www.sciam.com/article.cfm?articleID=00029C3D-E295-1CCE- B4A8809EC588EEDF&catID=1 http://www.sciam.com/article.cfm?articleID=00029C3D-E295-1CCE- B4A8809EC588EEDF&catID=1 o http://bordeaux.uwaterloo.ca/biology447/modules/module8/soil/chap2f.htm http://bordeaux.uwaterloo.ca/biology447/modules/module8/soil/chap2f.htm o http://www.extension.iastate.edu/carroll/crops/fertilizer_and_soil_ph.htm http://www.extension.iastate.edu/carroll/crops/fertilizer_and_soil_ph.htm o http://www.soils.wisc.edu/~bleam/SS230_FAQ98C.html http://www.soils.wisc.edu/~bleam/SS230_FAQ98C.html o http://www.rook.org/earl/bwca/nature/ferns/pteridiumaqui.html http://www.rook.org/earl/bwca/nature/ferns/pteridiumaqui.html o http://www.laspilitas.com/plants/526.htm http://www.laspilitas.com/plants/526.htm o http://rcgardens.ca/factsheets/factsheets/fernfacts.html http://rcgardens.ca/factsheets/factsheets/fernfacts.html o http://www.laspilitas.com/plants/676.htm http://www.laspilitas.com/plants/676.htm o http://www.laspilitas.com/plants/1095.htm http://www.laspilitas.com/plants/1095.htm o http://www.extension.umn.edu/distribution/horticulture/components/1731-29.html http://www.extension.umn.edu/distribution/horticulture/components/1731-29.html o http://www.na.fs.fed.us/spfo/pubs/silvics_manual/Volume_1/tsuga/heterophylla.htm http://www.na.fs.fed.us/spfo/pubs/silvics_manual/Volume_1/tsuga/heterophylla.htm o http://eesc.orst.edu/agcomwebfile/edmat/html/ec/ec1303/ec1303.html http://eesc.orst.edu/agcomwebfile/edmat/html/ec/ec1303/ec1303.html o http://reference.allrefer.com/wildlife-plants-animals/plants/shrub/vacpar/botanical-ecological- characteristics.html http://reference.allrefer.com/wildlife-plants-animals/plants/shrub/vacpar/botanical-ecological- characteristics.html o http://www.biodiversity.org.uk/ibs/envmath/resources/year3/env324/moffatt/HTMLfiles/i_aquifolium.h tm http://www.biodiversity.org.uk/ibs/envmath/resources/year3/env324/moffatt/HTMLfiles/i_aquifolium.h tm o http://www.crescentbloom.com/Plants/Specimen/GA/Gaultheria%20shallon.htm http://www.crescentbloom.com/Plants/Specimen/GA/Gaultheria%20shallon.htm