“Natural vs Chemical Fertilizers. Which one works the best?”

Question

To whom it may concern,

We are grade 6 students working on a science fair. The project we chose was “Natural vs Chemical Fertilizers. Which one works the best?” We noticed that that the naturally fertilized worked best, then not fertilized and finally chemically fertilized.

For the procedure, we planted 2 seeds (beans) in each container (6 containers). Two containers (4 plant seeds) were fertilized with natural fertilizer (eggshells, banana peels, tea leafs etc.).Two containers were fertilized with chemical fertilizer (12-4-8) and the remaining two containers weren’t fertilized. The amount of fertilizer in each container was ½ tsp every other Saturday / 14 days. A single plant was watered 15 to 20 ml each day with a spray bottle

We would like your opinion on which would work best – naturally fertilized, chemically fertilized or not fertilized and why.

If you would not mind answering my few question, that would be wonderful. Any feedback and other information would be gratefully received.

Answer 1

There are many different options of natural fertilizers; results will and can vary with these products.
This article has more information.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/types-of-organic-fertilizer.htm

Answer 2

What is your hypothesis? Your experiment must be designed with that in mind. Start with a sterile growing media; anything that supplies nutrients confounds your results. You could use a combination of sand and perlite. Neither has any nutritional value. By itself, sand can become compacted and this will impair root development. Perlite loosens it up. How long will the experiment run and what are you measuring as results? Plant height, green color, number of flowers, or root mass? The fertilizer you mention contains 3 ingredients: NPK or Nitrogen, Phosphorus and K+, the chemical symbol for potassium. It is easy to remember each’s function. Up, down and all-around: Nitrogen improves leafy growth up, Phosphorus boosts root development down and Potassium (aka potash) helps overall plant health and improves flowering. Learn what a cotyledon is. The seed provides all the nutrition that your sprouts need until they develop “true leaves”. Don’t fertilize before this. Is the pH of your water good for bean growth? Seedlings are not given mature plant doses of fertilizer. That would be like giving a toddler the same dose of Tylenol that an adult takes: it could be toxic to the plant and really screw up your results. The idea that you can “feed” plants by putting eggshells or peel on top of the soil is nonsense. Calcium that is bound up in a shell is not going to be available for plant roots to use. Beware trendy gardening ideas. There often is no science to back them up. You must use the final product of their breakdown which is compost. Every batch of compost has slightly different NPK so comparing inorganic fertilizer to compost is already complicated. Compost also contains nutrients in addition to NPK: more complication to interpreting results. But 6th grade science doesn’t need to be perfect! The human body can’t tell the difference between vitamin C made in the lab and vitamin C from oranges. Can plants tell whether nitrogen comes from the lab or from compost? There are many benefits to using compost that go beyond nutrients. And too much or poorly timed inorganic fertilizer is detrimental. But for the average backyard gardener which one is better? Chemical fertilizer is cheaper than purchased compost. The richest soils in nature are found on the forest floor. Years of fallen leaves and branches naturally make compost and enrich the soil. Your watering regimen doesn’t encourage deep root development. And how much water a plant needs is variable. It needs more water in hot, windy or dry air and if it is in direct sunlight. Lack of sufficient water may severely impair the bean’s growth; how will you tell water deficit from nutrient deficiency? Plant growth is more complex than water and NPK; for this reason, I vote for finished compost as the best supplement for the garden.