Grade by Grade
E. Earth and Space Systems · Soils in the Environment

Keeping Soil Healthy in Ontario

E2.5 E1.2 A1.3 A2.2 A3.1 A3.3About 45 minutes
Learning goals
  • I can describe strategies Ontario farmers use to keep soil healthy.
  • I can describe things families and communities can do to keep soil healthy.
  • I can explain how some new technologies help farmers care for soil.
  • I can design, build and test a way to stop soil erosion on a hill.

Words to know

strategy
A plan or way of doing something to reach a goal.
cover crop
A crop, like rye or clover, planted to cover and protect the soil, not mainly for food.
crop rotation
Growing a different crop in a field each year, in a pattern.
no-till
Planting seeds without ploughing (turning over) the soil first.
windbreak
A row of trees or bushes that slows down the wind.
sensor
A tool that measures something, like how wet the soil is, and sends the information to a computer.

Soil doctors

When you feel sick, a doctor helps you get healthy. When you are well, you stay healthy by eating good food, sleeping and exercising.

Soil needs care too! Farmers, gardeners and scientists in Ontario use many strategies to keep soil healthy and to make tired soil healthy again. Today you'll learn their tricks, and then you'll be an engineer and design your own soil protector.

Strategies on Ontario farms

  • Cover crops. After the harvest, many farmers plant a cover crop, like rye, oats or clover. It covers the soil over fall and winter. Its roots hold the soil so snowmelt and wind can't carry it away. When it dies, it adds humus.
  • Crop rotation. Farmers change crops each year in a pattern. Many Ontario farms grow corn, then soybeans, then wheat. Different crops use different nutrients, and soybeans (like other beans) help add nitrogen to the soil.
  • No-till or less tilling. Ploughing turns soil over, which can leave it bare and break up its crumbs. With no-till, a special machine plants seeds right through the leftover stalks from last year. The old stalks cover and protect the soil.
  • Windbreaks. Rows of trees along the edges of fields slow the wind so it can't blow soil away.
  • Grassy strips by streams. Strips of grass and trees beside creeks catch soil and extra fertilizer before they reach the water.
  • Adding organic matter. Spreading manure and compost adds humus and nutrients.
  • Testing soil. Farmers send soil samples to a lab to find out which nutrients are missing, so they add only what is needed.
  • Keeping heavy machines off wet fields to prevent compaction.
A farm field in late fall with short corn stalks left from the harvest and green cover crop grass growing between them.
After the corn harvest, this farmer planted a cover crop. Its roots hold the soil so wind and snowmelt cannot carry it away. AI-generated image
YEAR 1cornYEAR 2soybeansYEAR 3wheatthen startagain
A crop rotation used on many Ontario farms: corn, then soybeans, then wheat, then start again. Soybeans help add nitrogen to the soil.

Remember the Three Sisters

Planting different crops together, like the Three Sisters (corn, beans and squash) grown by the Haudenosaunee and other First Nations, is also a soil-care strategy. The beans add nitrogen and the squash leaves cover the soil.

Strategies at home and in your community

  • Compost food scraps and add it to gardens.
  • Spread mulch or leave some fallen leaves on garden beds in the fall.
  • Plant grass, trees and gardens, especially on slopes, so soil is never bare.
  • Make a rain garden in a low spot so rainwater soaks in.
  • Don't walk on garden beds, especially when they are wet.
  • Shovel snow first, and use only a little salt.
  • Never dump chemicals. Pick up litter.
  • Join a tree planting or a community garden.

Technology helps soil (and coding helps technology)

New technologies help farmers care for soil:

  • Soil sensors in the ground measure how wet the soil is and send the information to a phone or computer. Farmers water only when the soil is really dry.
  • GPS helps tractors know exactly where they are in a field. Computer programs can tell the machine to add fertilizer only in the parts of the field that need it, not everywhere.
  • Drones and pictures from satellites show which parts of a field are healthy and which need help.

All of these use code: instructions written by people that tell computers and machines what to do. For example: if the soil is dry, then turn on the water.

These tools can save water and fertilizer and protect the soil. They can also be expensive, so not every farm has them.

Worked example

Let's match problems and strategies

Choose a strategy for each problem.

  1. Problem 1: A field is bare all winter, and soil washes away in the spring melt. Strategy: plant a cover crop in the fall.
  2. Problem 2: Wind blows dry soil off a flat field. Strategy: plant a windbreak of trees.
  3. Problem 3: Soil and fertilizer wash from a field into a creek. Strategy: plant a grassy strip beside the creek.
  4. Problem 4: A garden's soil is pale and has little humus. Strategy: add compost and mulch.
  5. Problem 5: A farmer doesn't know which nutrients her field needs. Strategy: test the soil.

Each problem has a strategy that fits it. Good soil care means choosing the right strategy for the problem.

Worked example

Let's design: Stop the hill from washing away!

Engineer challenge: A model hill of soil in a pan loses lots of soil when you pour water on it. Design something to keep the soil on the hill.

  1. Problem: Water washes soil down the hill. Criteria (what success looks like): after pouring 250 mL of water, less soil washes down than on a bare hill. Use only things from home.
  2. Brainstorm ideas: a wall of craft sticks across the slope (a retaining wall), steps (terraces) pressed into the hill, a layer of mulch (shredded paper or leaves), or a mat made from an old cloth.
  3. Plan and build: Liam chooses craft-stick walls plus leaf mulch. He draws a plan, then builds it.
  4. Test: He pours 250 mL of water slowly from a cup with holes. He scoops the soil that washed down with a spoon and counts: bare hill 10 spoonfuls, his design 3 spoonfuls.
  5. Improve: Water ran around the end of one wall. He makes the walls longer and tests again: 1 spoonful.

Liam's design worked: 10 − 1 = 9 fewer spoonfuls of soil washed away. Engineers plan, build, test and improve.

Spoonfuls of soil washed down024681010bare hill3first design1longer wallsfewer spoonfuls = the soil protector works better
Liam's tests. Each change to his design let less soil wash down the hill: 10, then 3, then 1 spoonful.
Just for fun

Why did the farmer plant clover after the harvest?

So the field would have a cozy cover for the winter!

Hands-on activity

Engineer a soil protector

You need: a baking pan or plastic tub, soil, a book to prop it up, a cup with small holes poked in the bottom (a grown-up pokes them), a measuring cup, a spoon, and building materials such as craft sticks, toothpicks, small stones, leaves, shredded paper, cotton balls or a scrap of cloth.

  1. Pile the soil into a hill at one end of the pan. Prop that end on a book.
  2. Test a bare hill first: pour 250 mL of water through the holey cup onto the top. Count the spoonfuls of soil that wash to the bottom. Rebuild the hill.
  3. Design: draw a plan with labels. Which strategies will you use: walls, steps, mulch, a cover?
  4. Build your design.
  5. Test with 250 mL of water again. Count the spoonfuls.
  6. Improve your design and test again. Did it get better?
  7. Share: which strategy worked best, and which real strategy is it like?

Safety: A grown-up pokes holes. Toothpicks are sharp at the ends; handle them carefully. Do it outside or in a sink. Wear gloves, or wash your hands with soap when you are done.

Your turn

1

What is a cover crop? How does it help soil?

2

What is crop rotation?

3

How does a windbreak protect soil?

4

Name two things your family can do to keep soil healthy.

5

How can a soil sensor help a farmer?

6

Name the steps engineers use to solve a problem.

7

Why do farmers test their soil?

More practice: warm-up

1

True or false: Leaving a field bare all winter protects the soil.

2

Name one cover crop.

3

What does no-till mean?

4

Should you walk on a wet garden bed?

5

What tells a tractor exactly where it is in a field?

More practice: on your own

1

How does no-till farming help protect soil?

2

Why are grassy strips planted beside creeks?

3

Why does a corn, soybean, wheat rotation help soil?

4

Name one good thing and one problem with farm technology like GPS tractors.

5

Write an "if... then..." rule a soil sensor could follow.

Challenge

1

A farm field is on a slope beside a creek, and it is bare in winter. Name three strategies that would help, and say what each one does.

2

In a design test, a bare hill lost 12 spoonfuls of soil. Design A lost 5, Design B lost 2. Which worked better, and how many fewer spoonfuls than the bare hill?

3

Your craft-stick wall design is like which real soil strategy? Explain.

Check your understanding

Quiz

1.

A cover crop is planted mainly to...

2.

A row of trees beside a field that slows the wind is a...

3.

Corn one year, soybeans the next, then wheat. This is called...

4.

A soil sensor can tell a farmer...

5.

Which is not a good soil care strategy?

6.

In the engineering design process, after you test your design, you...

For parents and teachers

Big idea (E2.5): Ontario farmers maintain and improve soil health with cover crops, crop rotation, reduced tillage or no-till, windbreaks, vegetated buffer strips and grassed waterways, adding manure and compost, soil testing and nutrient management, and avoiding compaction. Ontario's agricultural soil health strategy ("New Horizons", 2018) promotes these practices. Families can compost, mulch, plant, avoid compaction and use less salt (A3.1).

Technology (A2.2): Soil moisture sensors, GPS guidance, variable-rate application and drone or satellite imagery let farmers apply water and fertilizer only where needed. Discuss benefits (less waste, cleaner water) and limits (cost). The "if dry, then water" rule is a first taste of conditional coding.

Engineering (A1.3): The hill challenge follows the engineering design process: define the problem and criteria, brainstorm, plan, build, test, improve. Praise improvements, not just a perfect first try.

Common difficulties: Children may think farmers "harm" soil. Many Ontario farmers are leaders in soil conservation; present farming as a partnership with soil.

Safety: Adults poke holes; careful with toothpick points; outdoor or sink testing; gloves or hand-washing after handling soil.