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Soil or Dirt?
Transcript of Soil or Dirt?
What's the difference between soil and dirt?
An estimated 5 to 50 billion bacteria and 5,000 to 100,000 fungi are in every tablespoon of healthy soil.
What's soil made up of?
Humus is usually dark in color, is fluffy, smells slightly sweet and is considered ideal soil. It has nutrients, and it's texture also holds nutrients in well. Because of it's texture it also holds the nutrients it has.
not this hummus
2. Air and water
3. Organic matter
Minerals are the "inorganic" part of soil. Minerals have never been alive, they are solid particles that have been broken down from rock.
Soil Texture, Structure and Drainage
Plants will grow differently in different soils. In the picture below the first group has nothing added, the second has fertilizer, the third has an amendment that improves soil structure along with fertilizer.
If you want strong, healthy plants, nothing is more important than good soil.
What is soil made of?
Minerals, air, water and organic matter.
This "parent" rock material differs in mineral content depending on where it came from.
Dirt is just dirt bits of rock and non-living things - soil is what has nutrients for plants to live.
Five percent of soil is "organic matter"
This comes from dead plants, animal waste, and living things that have died and
In the Soil Organic Matter, some is fresh, it just died.
Soil organic matter is about 5% of soil. In some soils It could be much more or less, from 0- 20%
Some of it is actively decomposing- the nutrients aren't yet available to plants.
Some of it is stabilized organic matter- it is finished breaking down and the nutrients are now available to plants.
Organic matter that has finished breaking down is called Humus.
The texture of Soil Organic Matter is perfect for giving the soil the right
and making it possible to hold a good balance of air and water.
no organic matter
lots of organic matter
Soil structure determines how much and how often plants need water and fertilizer. Humus, or Soil Organic Matter is an excellent addition to any soil.
What can we tell about soil fertility by color?
A dark color is a good indicator that there is a lot of Carbon present. All life forms have carbon in them, so this is a good indicator of soil organic matter.
A tiny portion of organic matter in soil is actually living micro-organisms. They need healthy soil structure to get a good balance of air and water.
These creatures are essential for decomposing organic matter and keeping the soil healthy.
Plants LOVE having micro-organisms around their roots to help them get more nutrients than they could otherwise get.
Of course, they need a source of organic matter. Compost, manure, and mulch feed micro organisms.
cows, horses, chickens all provide great manure.
Compost can be from leaves or other plant materials.
Bacteria and fungi break down waste and decay into nutrients plants can use.
means living or once-living.
in the soil is part of the "biotic" category.
To ensure you have plenty of beneficial soil micro-organisms, and not just the bad ones, build organic matter in your soil every year.
What makes dirt into soil is organic matter.
Dead living things
Fresh organic matter feeds the micro-organisms
...and fight off pests.
Different soils hold water and nutrients differently.
It's important to know what soil type you have to know what nutrients it has, what it will hold, and how it needs to be irrigated.
Soils vary around the world, but soil texture can always be defined as a mix of sand, silt and clay.
They say "Loam" is a balanced mixture of Clay, Sand and Silt.
But really, loam will almost always have lots of organic matter in it.
Why does soil matter?
Plants need healthy, fertile, well draining soil to grow strong steams, leaves, produce big fruits,
Plants need nutrition and a good environment to grow strong and have healthy immune systems, just like people.
Plants are more likely to suffer from disease if they have poorly structured soil, or soil that lacks any of the elements plants need.
dark soils are usually more fertile, why? what makes them dark?
Plants do get diseases from a few strains of bacteria and fungi- but most of them are good! Microscopic bugs, bacteria and fungi are an important part of healthy soil.
We can't get rid of them, anyway.
That last part of soil is water and air- which really means pore space for water and air.
Macropores are created by plant roots, worms, and insects.
Too much compaction can destroy pore spaces.
That's why planting in soil that's hasn't been walked on, or driven over too much is so important for plants.!
Ideally, you want your soil texture to be a fluffy loam, with a balanced mix of sand, silt and clay, and lots of organic matter.
This will be dark in color, smell sweet, and have a texture that is slightly sticky.
It will have lots of micro and macro-pores, and the organic matter will invite micro-organisms to come decompose organic matter and make more pores.
What do you need to know?
Learn more in the soil fertility presentation.
The mineral part of soil is rock that has been eroded and weathered over the years down to tiny tiny pieces.
This rock has many micronutrients plants need, but rarely any of the macronutrients.
Air and water
Both the plants and the beneficial micro organisms that live in the soil need air and water. Pore space is an important factor in soil health.
Macropores are large channels water flows through, micropores retain water after most of it has percolated down.
Micro pores are created by soil micro-organisms, bacteria and fungi.
Knowing what kind of particles your soil is made of helps you determine how and when to add fertilizer and water. Test your soil texture by looking at it, touching it, and doing the jar test.
most nutrients are positive and will stick to clay.
What is "Soil?"
Topsoil is a very thin skin on top of much harder layers of dirt and rock.
When we talk about soil, we are talking about the top few inches- often no more than a foot. This is where most nutrients are, and most plant roots only extend through this layer.
The bedrock at the bottom is the "parent material" that breaks down into bits of dirt as it is weathered.
As plants grow and life transforms the surface of rock, organic matter accumulates and topsoil is formed.
For this presentation, we are going to focus on the physical composition of soil, and how that affects plant health and nutrition.
What is the soil made up of?
How will that hold water?
Will it allow in enough air?
What is the soil texture?
What is the soil structure?
How will that hold nutrients?
These particles aren't just different sizes, they are different shapes, and have different properties.
Sand is large and smooth, and doesn't have many places for air and water to be trapped, or for microorganisms to live.
Clay is the tiniest particle of soil. It is not only microscopically small, but it is flat and blocky. It retains more water, has more nutrients, and has lots of places for water to be trapped or microorganisms to live.
If you water sandy soil, it will drain faster, and spread out less than in clay soil.
Clay soils have a negative electrical charge, and gently hold nutrients in the soil solution.
Soil with too much clay can also become hard, compacted and prevent water and roots from penetrating. Or it can hold water so long plants will drown.
Sand also has no electrical charge, and doesn't hold nutrients well.
In size, silt is in-between sand and clay.
Silt is smooth like sand, and doesn't have much of a charge to hold nutrients. However it is good at holding water, like clay. Even to the point it can become waterlogged.
Silt isn't as chunky and angular as clay, it's relatively smooth.
If your soil has a really excessive amount of clay or sand or silt you can add other soils to it to make it a loam. Usually crops are chosen depending on the soil type that's already there. For a home garden you might have soil delivered.
The best way to get a healthy loam is to add organic matter. Almost any soil will benefit from more organic matter.
Organic matter creates good texture, structure, and has lots of nutrients.
Organic matter is also the best at holding nutrients, even better than clay.
Organic matter in action- Here's a microscopic picture of biochar, which is wood or grass burned in a special process. It increases the availability of nutrients in the soil.
Testing soil texture by feel:
Clay soils feel sticky
Silt feels smooth or like flour, or butter
Sand feels gritty
Coarse soils like sand will break with slight pressure, or even fall apart in your hand.
Medium texture soil like sandy loam and silty loam will stay together but change shape easily.
fine texture soil like clay or clayey loam will not fall apart, If there is a lot of clay, you can even sculpt it into a shape.
The jar test is a way to see visually what soil you have. Put a soil sample in a jar and shake it up. The soil will filter out in layers of sand, silt and clay.
Once you know your soil texture you can also take a look at soil structure.
Soil structure is how the soil sticks together, or aggregates.
Soil structure may vary due to the texture, elements in the soil, their electrical charge, and the action of soil microbes and fungi. organic material is also sticky and helps bind the soil into aggregates.
Water absorption and runoff will depend a lot on soil structure.
Proper soil management practices keep soil structure healthy. Plowing or tilling the soil can damage structure over time.
this has no nutrients for plants, but it allows them to have better access to the nutrients that are in the soil.
That's why we never walk where our plant roots are growing.
Soil structure matters!
Organic material is what nourishes plants and makes healthy soil structure. it's also the little creatures that live in soil.
What is soil, why does it matter, what do we need to know?
You can see sand and clay are very different. Silt is in-between.
Lots of things live in soil, what is soil?
Some soil is healthy and grows strong plants.
Some soil doesn't.
Why is soil so important?
Clay and loam soils will have more nutrients, hold more nutrients, and retain water longer. This is due to structure as well as electrical charge.
When adding fertilizer and when watering clay soils, it is good to add more, less frequently. When irrigating, water spreads out more in clay soils, instead of draining straight down.
Sandy soils have fewer nutrients, and are not very good at holding nutrients due to structure and a lack of electrical charge.
Sandy soils need more frequent watering (because they drain so fast) and need smaller doses of fertilizer less frequently.
(Because they can't hold on to it long and too much will burn the plant.)
Some micropores are so small, that plants can't get the water they hold. These aren't the micro-pores we're talking about.
You can use the soil identification pyramid to classify soils
sandy clay loam
silty clay loam
How will you have to fertilize?
To know what type of soil you have, there are some simple (and free) tests you can do.
Knowing your soil texture, structure, and drainage will affect how you water and fertilize your crops.
Organic Matter will have the perfect loamy texture to hold water and air. It also has both positive and negative charges to hold nutrients.
Sand is heaviest, and will filter out to the bottom first. Silt will be the next layer, and clay on top. Above that organic matter might float if it's not completely broken down.
Soil structure affects how water and air move through the soil, and to some degree, how roots can grow.
Soil structure can become poor due to a lack of organic matter, poor soil management practices, or the overuse of chemical fertilizers or pesticides that kill soil life.
To improve soil structure you can add soil amendments (see the soil amendments prezi) and organic matter.
Compacted or poorly structured soil won't drain well. That can cause water to runoff, and keep your plants from getting any, or it could cause water to stay stuck in the soil and drown them.
Both plants and micro-organisms need a healthy balance of air and water.
To test if the drainage of your soil is good, dig a hole and see how long it takes for water to drain out. One inch per hour is considered good drainage. Any slower and your soil is too compacted, or has too much clay.