How do different treatments
change how fast seeds sprout?
You can find out how quickly seeds sprout under
different temperatures, or after being soaked for different times or
in different liquids. Or, see how one kind of treatment affects different
types of seeds.
What effect does seed
size have on how well a crop like oats or wheat grows?
Pick out groups of seeds all of the same size.
Be sure and measure the seeds before you plant them. You
can define success a number of ways: how many seeds sprout, how fast
the plants grow, how tall the plants get, etc.
way is up?
Many seeds and bulbs have a definite top
and bottom. What
happens if you plant them upside down or sideways? Will they still grow?
Will it take longer for leaves to start showing up? You may have to
dig the bulbs up to measure root growth.
happens if you change a seed's direction once it starts to sprout?
Many seeds like beans can be sprouted in moist cotton or paper
towels. What happens if you turn the seed 90 or 180 degrees from right-side-up
every few days after it sprouts?
You can take it
a step further by using a record player turntable (if you can find one)
to simulate changing gravity's pull on seeds.
You'll want to know more about the chemical auxin, which affects where
roots and stems grow. Click here to learn
more about using the turntable.
the amount of room a plant has for roots make a difference in how big
a plant will grow--regardless of how much fertilizer the plant is given?
Plant seeds in a variety of different-sized containers using
vermiculite or other soil-less material, so you will be able to give
each plant a measured amount of fertilizer. Or plant a number of plants
in the same size containers and vary the amount of fertilizer and see
what happens. Be sure to use small enough containers so that root growth
really will be constricted.
How do different types
of fertilizers affect plant growth?
Fertilizers contain different amounts of the
nutrients nitrogen, phosphorus, and potassium. Get different fertilizers
from a garden shop or nursery and apply them to groups of the same plant.
Do the different fertilizers change how the plants grow? You could measure
height, width, number of leaves, how fast the plants grow, number of
flowers, or yield.
happens when you grow sweet potatoes next to other plants?
Compare how fast the other plants grow at different
distances from sweet potatoes. Remember to grow some control plants
nowhere near the sweet potato. Check out the term allelopathy.
does soil pH (acidity)
affect the pH of water that touches the soil?
A pH meter can be found at almost any garden
shop or nursery. Gather different types
of soil or look in a nursery for pottings for different types of plants.
Put some of each type in a cup and check out the pH. Then check the
pH of your water and add it to your cups, and mix. Wait for the soil
to settle and measure the pH of the water. Be sure you use water from
the same source for each soil. Click
here to learn more about soil from ARS's Coastal Plains Soil, Water,
and Plant Research Center.
Does soil type change
how well crops grow?
Fill boxes with different types of soils (sandy,
clay, etc.) and plant the same seeds in all the boxes. What happens
to the plants? You could measure height, width, number of leaves, how
fast the plants grow, number of flowers, or yield of seeds, or fruits
are different soil types affected by water running over them?
Farmers in many parts of the country have to
irrigate--to water their crops rather than rely only on the rain. But
water running over soil can cause it to wear away, or erode.
Here's a simple experiment: Find
patches of different types of soil that are on slight slopes or hillsides
(you could also look for patches of the same soil type with different
amounts of plant cover, for example, bare soil and a grassy area). For
each test site make a sampling container. Cut the tops off plastic bottles
such as soda bottles or milk jugs. Use the same size bottle for all
sites. Bury each container so the lip is even with or slightly below
the soil surface.Weigh the soil that collects in the containers after
each rain. Dry the soil in an oven before you weigh it; you don't want
to weigh the water, just the soil. Record the differences to find out
which test site had the most erosion.
there chemical contamination in your streams and creeks?
One way to test for such contamination
is with a bioassay, a type of experiment that measures the effect of
a substance on a living organism, tissue, cell, or enzyme.
Of all the
possible water-quality bioassay organisms, lettuce might be one
of the last you would think of. Lettuce doesn't live in water,
so why use it to test water quality?
The reason is lettuce bioassays
are inexpensive, easy to do, and the seeds are pretty sensitive
to some types of contaminants in water, including heavy metals,
pesticides and other organic toxins.
Although any variety of
lettuce may do, Lactuca sativa Buttercrunch is the standard
variety recommended for bioassays by the U.S. Environmental Protection
Agency, the Food and Drug Administration, and the Organization
for Economic Cooperation and Development.
You might try taking a series of
samples along one stream or compare streams near industry to water
running though agricultural areas.
Directions for conducting experiments can be
found at the Cornell University's Environmental
different varieties of the same fruit have the same level of vitamin
What about different
brands of orange juice? Or fresh juice compared to juice from frozen
concentrate? Does the way a fruit is stored or how long it is stored
change the level of vitamin C? Click here
to learn how to test for vitamin C content.
Are there different
amounts of iron in different breakfast
The iron in ready-to-eat
breakfast cereals is in the form called elemental, not in combination
with any other chemical compound. Iron is sprayed on the outside of
cereal flakes. Click here to learn how to
separate the iron with a strong magnet.
It's easy to think of all microorganisms as bad things--as
germs, for example. But many microorganisms are very helpful, especially
for agriculture, and some are even essential. Microorganisms are used
to fight pest insects, diseases and weeds that make producing crops
and raising livestock less efficient. Other microorganisms help make
nutrients in the soil more available to plants.
What happens to the way
plants grow if there are no microorganisms in the soil?
Take a sample of fertile soil from a field or
garden and divide it into two portions. Bake one in an oven (to destroy
the microorganisms). Leave the other portion alone as a control. Plant
the same number of seeds in each soil sample. Remember to treat both
samples the same while the plants are growing. Make sure all the plants
receive the same amounts of water and light, and are kept at the same
temperature. How do the plants differ as they grow?
Are different plants
affected in different ways by specific microorganisms?
Some microorganisms and plants form mutually
beneficial partnerships. For example, certain bacteria make a natural
nitrogen fertilizer for plants in the family called legumes. Peas, alfalfa,
and soybeans are legumes. The nitrogen-fixing bacteria are available
from garden supply stores and by mail order. Grow both legumes and non-legume
plants with and without the bacteria. Are there differences in how well
the plants grow?
(NOTE: Most schools have special rules
about doing any experiments that involve live animals. Be sure to check
with your teacher before you decide on such an experiment.)
different colors and types of cloth attract or repel insects from plants?
Plant a number of groups of the same type of plant near
each other, but far enough apart to surround each set with several feet
of fabric. Or, select several of the same kind of bush in one yard.
You want to use the same type of plant in the same place, so all of
the plants will have the same potential for insect damage.
Surround each group of plants with a different color
fabric. Be sure water can penetrate the fabrics. At set intervals, record
all the insects you can find on each plants and any signs of insect
damage on the plant. It is a good idea to check reference sources for
common insect problems of the type of plants you are using.
more agriculture-themed science project ideas, visit our "Hot
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