Although there are many factors contributing to successful farming operations, any farmer or gardener will tell you one of the most important elements is the soil. The soil is
the base for all plant life. In addition to being the anchor matter for the plant roots, it also provides water and nutrients for the plant. Plants grown in good soil will
perform better and experience fewer problems with insects and disease.
Soil by definition is made up of sand, silt and clay particles derived from rock broken down over thousands of years by climatic and environmental conditions (rain, glaciers,
wind, rivers, animals, etc). Sand particles are defined as particles between 2.00 - 0.05 mm in diameter (USDA) and they feel gritty in your fingers. Silt particles are
particles that are between 0.05 - 0.002 mm (USDA) and feel similar to flour. Clay particles are particles smaller than 0.002 mm (USDA) and feel sticky in your fingers when
wet and clump to the point that you can not see an individual particle without a microscope. These particles are derived from a number of different types of rock so defining
something as sand, silt or clay is about sizing the particles, not determining their original source. The amount of each of these components characterizes your soil. For
instance, if you have a lot of sand, your soil will drain quickly and in contrast if you have a lot of clay particles, your soil will often be compact and retain water.
In addition to the sand, silt and clay, you will also find nutrients, organic matter (decaying plant and animal material), and pore space (open space that holds air and water)
in soil. These characteristics also impact the growing conditions for your plant. Just like people need vitamins, plants need certain nutrients for proper growth and
development. The available nutrients affect plant growth below and above the ground and especially impact fruit production. Organic matter influences nutrient and pore space
content. As plants and animals decay they release additional nutrients and create new pore space. The pore space is important to soil structure (the arrangement of the
particles in relationship to each other). In an optimal situation about 50 % of the volume of the soil is pore space with half of that filled with water and half filled
with air (the other 50% is the sand, silt, clay and organic matter). Roots need air as much as they need water and the plant can actually suffocate or drown if completely
emerged in water for extended periods of time.
What is the best kind of soil? Well there is no such thing as the perfect soil, but there is a perfect soil for a particular plant. Each plant likes different conditions. In
general, common garden plants prefer a well-draining loam (a soil that is composed of approximately 40 percent sand, 40 percent silt, and 20 percent clay with plenty of organic
matter and ample pore space) however there are plants that grow better in sandy conditions and others that grow well in compact, clay soils.
Farmers begin by analyzing their soil and then determine the best crops to grow. Although soil can be amended and improved (adding organic matter is common practice to improve
drainage and nutrient content) on a large scale it is best to pick out a crop that will grow well in the soil available to you. With your school farm, you may have more
control over the soil you use (especially if you are using container gardens, raised bed gardens or indoor gardens), but the following activities will help you to practice
analyzing soils and discussing different soil properties including soil texture, drainage and nutrient content.
For more background information on soil visit:
Soil Texture: Soil texture is the way soil feels and it is determined by the amount of sand, silt and clay particles present. Here are two activities to
determine the particle make up of your soil. If you are starting an outdoor in-ground or raised-bed garden, try the activities using the soil from the prospective plot.
If you are going to create container gardens or indoor gardens, most likely you will be using a soilless potting mix (these mixes are usually made from peat moss, vermiculate
or perlite and are called soilless mixes because they do not include sand, silt or clay), so ask students to bring in soil samples from home or use soil from your playground
Ribbon Test: Take a small clump of soil and add water until it makes a moist ball. Next rub the soil together between your fingers. If the soil makes a nice,
long ribbon, then it has a lot of clay in it (thus sticks together well). If it crumbles in your hand, then it has a lot of sand. If it is somewhere in between, then you
probably have a good mix (a soil with a good mix of all 3 components is called a loam). Although this test does not give you an exact percentage of each component, it provides
a general description and it can be used in the field due to the ease of implementation (all you need is a little water).
Shake It Up: Invite students to further explore different soil components by creating "mudshakes" and watching components settle out. For each soil
sample, have students fill a clear plastic container about two-thirds full of water, then add enough soil to nearly fill it to the top. Also add a pinch of laundry detergent
to help the soil components separate well. Shake the container vigorously then observe it over the next couple of days as the particles settle into layers. Ask students to
hypothesize about the composition of the different layers. The larger particles (sand) are heaviest and will settle at the bottom, followed by silt with the last full layer
being clay. The clay may stay suspended and cloud the water for a long time. Organic matter will float on or just below the water surface.
Once the container has settled, compare the results to your ribbon test. How do they compare? Measure the height of each layer and than translate that into percentages for
each component (height of each component divided by height of the sample). Use the Shake It Up worksheet to help with your
Soil Drainage: Soil drainage is a critical factor when determining good crops for a particular site. Although having water available is certainly important,
too much water causes the plants to suffocate and also promotes many fungal diseases. Although there are some plants that grow well in boggy soils, most production crops
(vegetables, row crops, fruit trees) need good to excellent drainage. Below are two experiments to test the drainage of soil or potting mix for your prospective school
For an Outdoor Garden: Dig a 12-18 inch deep hole in the proposed location for your school farm project (a post hole digger will work well). Fill the hole
with water. If the water drains within a few hours, then the drainage is excellent, if it empties within 24 hours, then the drainage is acceptable and if it takes longer
than that, then you have poor drainage.
For Indoor, Raised Bed or Container Gardens: Obtain a collection of different types of soils and potting mixes from local garden centers and landscape supply
companies. When building raised beds, you usually order garden soil by the truck load from landscape supply companies. Many times the companies will have multiple blends of
soil with varying amounts of compost and organic matter for you to choose from. Check to see if they will donate samples of the different types of soil for you to test.
Indoor and container gardens usually use soilless potting mixes or garden soil amended with peat moss. A variety of types of potting soils are available at all garden
Fill 6-inch, plastic pots (make sure they have drainage holes) with the different types of soil and potting mixes you were able to obtain. Additionally, fill one pot with sand
to use for comparison. Add water to your pots until it emerges from the drainage holes. This is a sign that the soils are completely saturated. Wait 30 minutes to make sure
all excess water has drained.
One at a time, hold each pot over a plastic tray or clear plastic bowl (the tray or bowl needs to be able to hold up to 1 cup of water). Measure out 1 cup of water and
slowly pour it over each pot of soil. Record the amount of time it takes before water begins to emerge from the drainage holes. Continue to hold the pot over the tray or bowl
until it stops dripping and then measure the amount of water in the tray or bowl (pour back into the 1 cup measuring cup).
Use the Drainage Experiment Worksheet to collect the data and ask students to hypothesize what this means about drainage. The
faster the water began to drain, the better drainage the soil or potting mix possesses. Also the closer the end water measurement is to the original 1 cup of water, the better
the drainage of the soil or potting mix.
Generally you want your soil to hold moisture, but not stay too wet. Based on this information, what soil or mix do they think is best? For further exploration, give the
students a chance to feel each pot of soil and record whether or not it feels wet or moist. An additional method to test moisture is available by using a moisture meter which
uses sensors to detect water levels (many garden catalogs have these available or you may be able to borrow one from a local gardener).
Nutrient Content: Plants receive nutrients by absorbing them through their roots. The soil nutrients come from decaying plant and animal matter. As they
decompose, the nutrients are released into useable form into the soil.
Plants have 6 macronutrients (nutrients they need in large quantities: nitrogen, phosphorus, potassium, sulphur, calcium and magnesium) and 8 micronutrients (nutrients they
need in small quantities: iron, zinc, copper, molybdenum, boron, manganese, chlorine and nickel) essential to their growth and development.
Obtain a do-it-yourself soil test kit. These kits are available at local garden stores and from garden catalogs. Using your prospective soil, test the nutrient content of
your soil (most kits only test for pH and the big 3 nutrients: nitrogen, phosphorus and potassium). Write the results of each test on the chalkboard.
If you are planting an indoor garden, you can use these tests on your chosen mix too, however some mixes contain slow release fertilizers which will not read properly.
For soilless potting mixes, a better option is to check the bag for nutrient content and if you do not find information about it, contact the company for the details. Do not
be surprised to find out your soilless mix does not contain any nutrients. Often times this is the case so the grower can have complete control over the amount and timing of
nutrients supplied. So if you are using a potting mix, you may want to practice soil testing using a sample from your playground.
What do the results say about your soil's nutrient content? Does your soil have the nutrients needed for healthy plant growth? Will you need to supplement your soil with
additional nutrients through fertilizer or compost?
Do-it-yourself soil kits vary in their accuracy. For more accurate results, obtain a soil test kit from your local Cooperative Extension office or from
http://www.css.cornell.edu/soiltest/newindex.asp and send a test sample to the Soil Nutrient
Analysis Lab. Share the results with your class and compare to the results from the do-it-yourself kit. How do the results compare? How reliable were the do-it-yourself
soil test kits?
For Further Study: The Natural Resources Conservation Service (NRCS) has developed soil surveys which include soil maps and other information for farmers and
ranchers to help with land use and management. Originally these surveys were published in hard copy by the U.S. Department of Agriculture and could be obtained from your
state or local NRCS office. To ease distribution, these surveys are being added to the NRCS Web site
or distributed on CD. Check with your local NRCS office or
http://soils.usda.gov/survey/printed_surveys/ to determine the availability of your local
A site analysis includes a thorough evaluation of existing structures, plant materials, climatic and environmental conditions. During a site analysis, you take accurate
measurements of your site and notes about important factors that will impact your crops. The end result is a detailed map and report to be used when designing the layout of
your farm operation or landscape.
As a class, complete a site analysis for your school farm.
Steps for completing a site analysis for an outdoor location:
- Contact school maintenance staff to locate all utility lines (water, sewer, electric, gas, phone etc.). Never dig before learning the location of utility lines.
- Obtain a large tape measure (a 100-foot measure works well).
- Provide students with paper, clipboards (or cardboard pieces with paper clips) and pencils.
- Take the students outside to evaluate the site. Begin by making a rough sketch of the space and all the major landmarks on a piece of paper (if you are short on time or
concerned about the ability level of your students, you may want to create a sketch outlining the border and major structures ahead of time and make copies for them). Next
take exact measurements of the borders around the site and write it down on your sketch. Once you have measured the parameters, take measurements of the locations and
sizes of major trees, sidewalks, the utility lines and other structures. Write all measurements on your sketch.
- Identify and label the existing plant material.
- Using the site analysis worksheet as your guide, make notes about important environmental factors on your site. Write
answers on your sketch or on the site analysis worksheet.
- When you return to the classroom, instruct students to translate their sketches and measurements into maps drawn to scale by plotting them on a piece of graph paper. The
easiest scale is for 1 block to equal 1 inch or 1 foot, but you can adjust based on the size of your location and graph paper.
- Once they have completed their design of the space, ask them to write in notes about the environmental factors impacting the space. Color code the notes using colored
pencils or markers to provide contrast with the design. For instance, note areas with poor drainage with a brown marker, the direction of the sun with a yellow marker, and
the location of a water source with a blue marker.
The steps to completing an indoor site analysis include:
- Obtain a large tape measure.
- Provide students with paper, clipboards (or cardboard pieces with paper clips) and pencils.
- Draw a rough sketch of your classroom then measure the dimensions. Note the potential location for your indoor garden and measure the dimensions of that space.
- Measure and sketch other major features of the room (desks, bookshelves, electric outlets, etc.).
- Use the indoor site analysis worksheet to answer questions about important factors that will impact your growing space.
Write your answers on the sketch or worksheet.
- When you finish, instruct students to translate their sketches and measurements into maps drawn to scale by plotting them on a piece of graph paper. The easiest scale is
for 1 block to equal 1 inch or 1 foot, but you can adjust based on the size of your location and graph paper.
- After completing their design of the space, ask them to write in notes about the other factors impacting the space. Color code the notes using colored pencils or markers
to provide contrast with the design. For instance, note electric outlets using a red marker and water sources using a blue marker.
Although no space is perfect, if you decide after completing your site analysis, that the prospective location is not going to work well (for instance you notice it is too
close to a busy street or there are no electric plugs where you wanted to place grow lights), look for additional available space for your farm project.
In order to understand why some plants grow better in your area than others, there are a number of important concepts your students must learn including:
Plant Needs: Plants have 5 basic needs. They need water, light, nutrients, air and a place to grow.
- Water: Plants need water for a number of important processes including photosynthesis (production of food) and transpiration (evaporation of water from
the leaves into air that cools the plant and creates pressure to move water from roots to leaves). Water also aids in the absorption of some nutrients.
- Light: Energy from light is captured to use during photosynthesis. Photosynthesis is the process by which plants make their food.
- Nutrients: Just as people need vitamins, plants also need special nutrients to help them grow properly and for their biological processes to function.
- Air: Plants take in carbon dioxide and oxygen to use during photosynthesis.
- A Place to Grow: Plants need a place to call their own. Do they need soil? Actually, not all plants need soil. There are some plants called epiphytes
that are adapted to living in trees and absorbing water and nutrients from the air. However, they do all need enough space to grow to maturity so they can produce seed to
ensure their survival.
To test these plant needs, try to grow plants in the absence of one of these factors. For instance, try to grow a plant without water or try to grow a plant in a closet without
light. Use at least 2 plants for each experiment including one control (for instance grow one plant in the window and one plant in the closet but provide them with the same
amount of water, air, nutrients and space). Only test one variable at a time to isolate the results.
Plants' Needs Vary: Plants grow all over the world in different climates and environments. They all need access to the elements listed above, but they need
them in different quantities. Some need high light others need low light. Some need to take in a lot of extra nutrients, and some need very few. They are adapted to the basic
conditions (water, light, nutrients, air and place) available to them in their native environment (the place they originally grew). That does not mean they can not grow in
another environment, it just means they prefer those conditions, and grow best in places that provide similar conditions.
To demonstrate the fact that plants need different growing conditions you can perform experiments by growing different plant varieties, but providing constant growing conditions.
For example, you can obtain a number of plants with different water requirements such a cactus or a pothos ivy (low water needs), a begonia or cyclamen (medium water needs), a
potted azalea or miniature rose (medium to high water needs). Place all of them in a classroom window and water them once a week with the exact same amount of water. Keep a
journal monitoring their growth and development. (*Note if you do not see many differences, lower the amount of water the plants are receiving).
Another option is to grow the same plant in multiple conditions. For instance obtain 4 identical cactus plants and plant one in sand, one in garden soil, one in sand with a
clear plastic bottle covering the pot (creates a humid environment) and one in garden soil with a clear plastic bottle covering the pot. Track the growth and development.
These are just a couple of examples. Write the 5 plant needs on the board and challenge students to come up with ways to test how different plants need different conditions.
Have students write down one experimental idea and then detail the steps necessary to complete it. You can use the
Plant Needs Experiment Worksheet to help guide the students. Then as group or individual projects, implement as many of the
experiments as possible. When the experiments are finished, analyze the results and ask students to explain what they learned about plant needs and growing conditions.
Plant Life Cycles: Plants begin their life cycle as a seed that germinates and becomes a seedling maturing into a plant that then produces either a fruit or a
cone containing new seeds (and the cycle begins all over again). Although the steps in this process are the same for all plants, the actual life cycles vary in length and
schedule. There are two main categories of plants including annuals and perennials.
- Annuals: Annuals are plants that complete their life cycle during one growing season. Under normal conditions they begin as a seed, grow to full maturity,
produce seed and then die during one growing season. The two main types of annuals are cool season (growing season from late fall to early spring) and warm season
(growing season is from late spring to early fall).
If placed in protected locations, annuals can live longer than one season. For instance an impatient is a warm season annual in New York and will die when the first freeze hits.
However, if you bring it inside when cool weather arrives, it will survive longer. Even though it is alive inside during the winter, it is still considered an annual because it
would not live for more than one growing season under normal conditions.
- Perennials: Perennials are plants whose life cycle is longer than one growing season. There are three different categories of perennials:
- Herbaceous Perennials: Plants that live for many years after growing to maturity. The stems and leaves of herbaceous perennials die back each winter, but they come
back from the roots in the spring. Herbaceous perennials do not make wood, although their stems may become wood-like in appearance. Examples include: daylilies,
goldenrod, and coneflowers.
- Shrubs: Shrubs live for many years after growing to maturity and the stems make wood. They usually have multiple trunks and their height is usually less than 15
- Trees: Trees live for many years after growing to maturity and the stems make wood. They usually have a single trunk and are taller than 15 feet.
Plants for Your Site: Farmers grow plants adapted for their conditions because well adapted plants will have fewer problems with insects and diseases, will
need fewer inputs such as additional water and fertilizer, will need less care and therefore usually result in a profitable harvest. Using the information gathered in the other
activities in this module and by researching using the Internet (to provide technology link), horticulture books and seed catalogs, create a list of plants suitable for your
school farm project. Remind students to match your environmental conditions (especially light available, temperature, room to grow and water) to the needs of the plants. Ask
them to note whether plants are annuals or perennials.
For ideas and resources on outdoor crops for your area, contact your local Extension Office or visit:
For ideas and resources on indoor crops:
Check out the book GrowLab®: A Complete Guide to Gardening in the Classroom and GrowLab®: Activities for Growing Minds or visit: