The Best Plant Food
Nutrient Differences in Soils
Fertilizer is a natural or synthetic chemical substance or mixture of substances used to add nutrients to soil so as to promote plant growth.
Plants can grow in natural environments without the assistance of commercial fertilizers. The soil seems to provide all the nutrients the plants need. Is there a difference in the nutrients in soils from one location to another?
In this project you will test the effects on plant growth of nutrients leached from soil samples taken from different environments. You will also discover which nutrients are best for plants.
Purpose: To determine whether nutrients leached from potting soil are sufficient for plant growth.
- 2-quart (2-liter) food colander
- two 2-gallon cooking pots or containers with openings large enough to support the colander
- two 2-by-2-foot (60-by-60-cm) pieces of cheesecloth
- 2 quarts (2 liters) of potting soil
- 1-quart (1-liter) jar
- 4 gallons (16 liters) distilled water in plastic jugs
- marking pen
- masking tape
- 8 house plants (same kind and size and each with five or more leaves) in similar containers
- Place the food colander over the opening in one pot so that the rim of the pot supports the colander.
- Line the inside of the colander with one piece of cheesecloth.
- Fill the cloth-lined colander with potting soil.
- Use the jar to pour 2 gallons (8 liters) of distilled water evenly over the soil (see Figure 26.1). Note: It will take time for all of the water to drain through the soil, so add the water slowly. The water that has drained through the soil is called the filtrate.
- After all the filtrate has drained through the soil, lift the soil-filled colander and place it over the empty pot.
- Pour the filtrate through the soil again.
- Repeat steps 5 and 6 three times. Keep the washed soil.
- Use the funnel to pour the filtrate into the two empty water jugs. Cap the jugs.
- With the marking pen and tape, label these jugs "Nutrient Filtrate."
- Label the remaining jugs of water "Water Only."
- Fill one of the cooking pots about three-fourths full with tap water.
- Remove the plants from their containers. Gently shake the soil from their roots and stand the plants in the pot of water to soak off more soil.
- Remove all the soil from the plant containers, rinse them with tap water, and repot the plants using the washed soil from step 7.
- Use the marking pen to label four of the plant containers "Water Only" and the remaining four "Nutrient Filtrate."
- Place all the plants together in a spot where their environment (temperature, amount of sunlight, and so on) is the same.
- Keep the soil moist, but not dripping wet, consistently using the liquid indicated on the plant container's label. Add the same amount of liquid to each plant, and water them all at the same time.
- Observe and record the growth of the plants for four or more weeks.