Science Fair Project on pH and Macronutrients in Soil

Macro Factor: A Study of pH and Macronutrients in Soil

Earth Science Biology Soil Macronutrients

Science Fair Projects on ph and Macronutrients in Soil

Megan
8th Grade - Age 13
Texas, USA

Project Research and Problem

After noticing that in my backyard some plants thrived and others did not, I wanted to find out what causing this. After researching the topic, I learned that aside from the necessary water and sunlight a plant needs to grow, there are thirteen nutrients that affect the growth of plants. Most everything I read also indicated that there are four major factors that affect the growth of plants. They are the level of pH in the soil and three macronutrients—Nitrogen, Potassium, and Phosphorus.

Hypothesis

I decided that the pH, Nitrogen, Phosphorus, and Potassium levels in the soil may be affecting plant growth. I figured the pH of the soil was fine, but thought maybe the macronutrients were low in some areas and adequate in other, thus causing the varied plant growth.

Materials

Image of sciene fair projects: soil samples

I prepared for my experiment by gathering the following materials: My log book, a Rapitest soil test kit, measuring cups, distilled water, paper plates, plastic cups, a timer, and for safety purposes, protective eye gear and latex gloves.

Experiment

Image of sciene fair projects: testing soil samples

To confirm my hypothesis, I collected 10 soil samples throughout the yard where the plants showed signs of growth problems and areas where growth was normal. I then used the Rapitest Soil Test kit to determine the levels of the pH, Nitrogen, Phosphorus, and Potassium levels in the soil.

Results

The pH level of the soil in my backyard was within its normal range and therefore allowed for all nutrients to be absorbed. The Potassium and Phosphorus levels varied but were within normal range for the plants in my yard. Nitrogen levels, however, showed signs of deficiency in almost every area.

Conclusion

So, I proved my hypothesis correct. The pH in my yard was within its normal range, which made the nutrients in the soil available to the plants. And as I expected, the soil’s macronutrients were causing the problems with my plants. Any number of reasons could be contributing to the depletion of the macronutrients—leaching, plant growth, lack of organic matter, or even the fact that there has been no commercial fertilizer added to my backyard in over 2 years.

I would say it is time to replenish the macronutrients in my yard, but I think I will avoid commercial fertilizers and try my hand at creating my own organic fertilizer. I have been doing a little research on composting and compost tea as a way to replenish my soil’s Nitrogen. Then not only can I rest on my porch swing and enjoy a green healthy view, but I can know that my fertilizer is having a positive effect on the environment.

What I Would Do Differently

In future projects I would test the soil samples more then once to reduce the amount of experimental error. I would also test through out the year (spring, summer, autumn, and winter) to find out if the time of year could possibly affect the levels of pH, Nitrogen, Potassium and Phosphorus in the soil. I would also like to test the soil after a fantastic thunderstorm to see how much Nitrogen entered the soil. Another thing I could test for are the micronutrients. Plants need 13 essential elements from the soil. Maybe they were deficient in one of the micronutrients.

Bibliography

Black, Dr. Bob. Soil pH and Landscape Plants. Dr. Bob’s Gardening Tips. http://hort.ifas.ufl.edu/gt/soilph/soilph.htm. July 12, 2006.

Grow Like a Pro. Easy 10 Point Check List. Online Gardening Information. http://gardencenter.southernstates.com/lawn/createcheck.shtml. July 12, 2006.

Helping People Understand Soil. Natural Resources Conservation Service. http://soils.usda.gov. July 12, 2006.

Jauron, Richard. The Meaning and Importance of Soil pH. Horticulture. http://www.ipm.iastate.edu/ipm/hortnews/2002/5-24-2002/soilph.html. July 12, 2006.

Kilkelly, Francis. Soil pH and it’s Affect on your Garden. An Information About Anything Website. http://www.phillyburbs.com/pb-dyn/news/287-05242006-661023.html. July 12, 2006.

National Garden Association. Garden Planning. Good Earth Horticulture Inc. http://www.goodearth.org/planning.cfm. Oct. 18, 2006.

Nutrient Management. Natural Resources Conservation Service. http://www.nrcs.usda.gov/feature/backyard/nutmgt.html. Oct. 18, 2006.

Owen, Marion, Acid or Alkaline? What pH Means in Gardenspeak. Plantea, The Organic Plant Food for every Occasion. http://www.plantea.com/pH.htm. July 12, 2006.

Plant Nutrients. North Carolina Department of Agriculture and Consumer Services' Kids World. http://www.agr.state.nc.us/cyber/kidswrld/plant/nutrient.htm. Oct. 18, 2006.

Soil pH Facts. Canabisgiving. http://www.greenmanspage.com/guides/phfacts.html. July 12, 2006.

Soil pH Requirements For Growing Garden Vegetables. Online Gardening Information. http://www.thegardenhelper.com/soilPH.htm. Oct. 18, 2006.

Soil Testing and pH Control. Home Harvest Growing Supply. http://homeharvest.com/soiltesting.htm. Oct. 18, 2006.

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