Researching the Problem: Fertilizer
Directions: Read the information that was gathered by 2 middle school students from
California. After you have read their research on Fertilizer, answer the questions.
Problem - What is the effect of fertilizer on plant growth?
- Independent variable: amount of ________________
- Dependent variable: ______________________
- Experimental Group: group of plants that received fertilizer
- Control Group: group of plants receiving no fertilizer
Importance of Plants
Without plants humans couldn’t live. For one reason, plants provide oxygen and food. The
plants are what animals eat, and humans eat some of the animals. Also, we live in houses
that you use trees to make, and some of our clothes are made of cotton, which come from
the cotton plant.
Plants provide many things like shelter, food, inks, oxygen, paper, fuels, medicine, clothing,
perfume, ropes, alcohol, sports equipment, photographic film, shade, soaps, rubber, dyes,
paints, plastics, and musical instruments. The best soil for plants is when the elements
include nitrogen, potassium, and phosphorus. Plants can help the environment by preventing
floods, lowering noise, producing oxygen, absorbing carbon dioxide, acting as windbreaks,
making the air cool, and reducing soil erosion. Photosynthesis is the process that plants go
through to produce their goal. This process requires big amounts of these nine chemical
elements carbon, hydrogen, oxygen, nitrogen phosphorus, potassium, calcium, magnesium,
and sulfur. Home garden growers can grow many things like flowers, grass, and food such as
fruit and vegetables. Farmers grow practically all of the food that people eat. They also grow
food for animals so farmers can raise them for meat, eggs and milk.
“Fertilizer is a substance that is added to soil to help plants grow. Farmers use various kinds
of fertilizers to help produce abundant crops. Home gardeners use fertilizers to raise large,
healthy flowers and vegetables. Landscapers spread fertilizers on lawns and golf courses to
help grow, thick, green grass. ” -World Book Encyclopedia. There are three main elements in
fertilizer. They are nitrogen, potassium, and phosphorus.
Synthetic fertilizer is the most widely used fertilizer in the world. It is water-soluble and
provides a quick boost of growth. If you apply too much synthetic fertilizer you can kill your
plants. Synthetic fertilizer has advantages in the spring because if it is applied as a liquid, it
can still go into cold soil. The strength of the components in fertilizer are usually listed on the
Since the three main components in fertilizer are nitrogen, potassium, and
phosphorus, a fertilizer listed as 16-16-16 would have 16% of each component. Another
fertilizer with 40-5-0 would have 40% nitrogen, 5% potassium, and 0% phosphorus. What do
you think a fertilizer labeled 20-40-40 would have in it?
Natural fertilizers are manure, sludge, guano (Bat waste), or dead or rotten organic
materials. Natural fertilizers have less nutrients than synthetic fertilizers do, but natural
fertilizers help keep the soil moisturized. Manure is the most important of the organic
fertilizers because it’s a mix of liquid and solid animal waste.
What Fertilizer Is Used For
Fertilizer is used for making plants grow faster and more healthy. Fertilizer can be made by
chemicals or by manure and other natural materials. You need fertilizer if your plants need a
boost of growth in a short amount of time.
Fertilizers and Farming
Fertilizer has been used for thousands of years. The right minerals don't return to depleted
soil so farmers must add fertilizers with the right minerals and elements to help the soil grow
good products. If farmers didn’t have fertilizer, more labor and land would be needed to
produce the same amount of food. Scientists found the chemical elements that are essential
for plant nutrition in the 1800’s and early 1900’s. Fertilizer has carbon, hydrogen, oxygen,
nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Air and water give most of
the carbon, hydrogen, and oxygen that plants need. Fertilizer helps phosphorus and
potassium increase root growth and vegetable production. In fertilizer, there is a small
amount of micronutrients. Micronutrients are boron, chlorine, copper, iron, magnese,
molylodenum, and zinc. The two main types of fertilizers are mineral and organic. Organic
fertilizer comes from animal matter, decayed plant, wood ashes, or sewage. Mineral
fertilizers are very wildly used. Mineral fertilizers are produced from ammonia gas.
Manufacturers make mineral fertilizers from synthetic substances. The nitrogen in fertilizer
helps leaves and stems grow. It has been used for golf courses, farmers, and home garden
growers. Farmers buy the most amount of fertilizer yearly. They remove the decayed plants
out of the crops before fertilizing because if they don’t they can have too much fertilizer in
Questions: Now that you have finished your reading, answer the following questions about your
Research on Fertilizer. USE COMPLETE SENTENCES.
ALSO, wherever you find your information in the text, UNDERLINE the words that helped you
get your answer.
1) In the experiment we will be doing, what are the independent and dependent
variables? (Hint. Independent Variable= what we control)
a. Independent Variable:_______________________________________
b. Dependent Variable: ________________________________________
2) How do plants help us on Earth?
3) What is fertilizer and what is fertilizer made of?
4) How does fertilizer help plants?
5) How can fertilizer hurt plants?
6) Give one reason why synthetic fertilizer is better for plants than natural
7) Give one reason why natural fertilizer is better for plants than synthetic
8) What are the percentages of elements in a fertilizer that is labeled 40-40-20?