PDC LESSON 4.13 SOIL - KNOW YOUR SOILS
PDC LESSON 4.13 SOIL - KNOW YOUR SOILS
There are 6 different soil types that gardeners and growers usually work with. All five are a combination of just three types of weathered rock particles that make up the soil: sand, silt, and clay. How these three particles are combined defines your soil’s type — how it feels to the touch, how it holds water, and how it’s managed, among other things.
SANDY SOIL
Sandy soil has the largest particles among the
different soil types. It’s dry and gritty to the touch, and because the
particles have huge spaces between them, it can’t hold on to water.
Water drains rapidly, straight through to places
where the roots, particularly those of seedlings, cannot reach. Plants don’t
have a chance of using the nutrients in sandy soil more efficiently as they’re
swiftly carried away by the runoff.
Testing what type of soil you’re working with
involves moistening the soil and rolling it into a ball to check the
predominating soil particle.
When you roll the slightly wet sandy soil in
your palms, no ball should be formed and it crumbles through your fingers
easily.
SILTY SOIL
Silty soil has much smaller particles than sandy
soil so it’s smooth to the touch. When moistened, it’s soapy slick. When you
roll it between your fingers, dirt is left on your skin.
Silty soil retains water longer, but it can’t
hold on to as much nutrients as you’d want it to though it’s fairly fertile.
Due to its moisture-retentive quality, silty soil is cold and drains poorly.
Silty soil can also easily compact, so avoid
trampling on it when working your garden. It can become poorly aerated, too.
CLAY SOIL
Clay soil has the smallest particles among the three,
so it has good water storage qualities. It’s sticky to the touch when wet, but
smooth when dry.
Due to the tiny size of its particles and its
tendency to settle together, little air passes through its spaces. Because it’s
also slower to drain, it has a tighter hold on plant nutrients. Clay soil is
thus rich in plant food for better growth.
Clay soil is cold and, in the spring, takes time
to warm since the water within also has to warm up. The downside is that clay
soil could be very heavy to work with when it gets dry.
Especially during the summer months, it could turn
hard and compact, making it difficult to turn. (When clay soil is worked while
it’s too wet though, it’s prone to damage).
If moistened soil feels sticky, rolls up easily,
and forms into a ball or sausage-like shape, then you’ve got yourself clay.
PEATY SOIL
Peaty soil is dark brown or black in colour,
soft, easily compressed due to its high water content, and rich in organic
matter. Peat soil started forming over 9,000 years ago, with the rapid melting
of glaciers. This rapid melt drowned plants quickly and died in the process.
Their decay was so slow underwater that it led
to the accumulation of organic area in a concentrated spot.
Although peat soil tends to be heavily saturated
with water, once drained, it turns into a good growing medium. In the summer
though, peat could be very dry and become a fire hazard. (I kid you not – peat
is the precursor of coal.) The most desirable quality of peat soil, however, is
in its ability to hold water in during the dry months and its capacity to
protect the roots from damage during very wet months.
Peat contains acidic water, but growers use it
to regulate soil chemistry or pH levels as well as an agent of disease control
for the soil.
When wet peat soil is rolled, you won’t form a
ball. It’s spongy to the touch and when squeezed, water could be forced out.
SALINE SOIL
The soil in extremely dry regions is usually
brackish because of its high salt content. Known as saline soil, it can cause
damage to and stall plant growth, impede germination, and cause difficulties in
irrigation.
The salinity is due to the build-up of soluble
salts in the rhizosphere – high salt contents prevent water uptake by plants,
leading to drought stress. It’s easy enough to test if you have saline soil.
You’ll probably see a white layer coating the surface of the soil, your plants
are growing poorly, and they’re suffering from leaf e burn, especially on young
leaves.
LOAM SOIL
The type of soil that gardens and gardeners love
is loamy soil. It contains a balance of all three soil materials – silt, sand
and clay – plus humus. It has a higher pH and calcium levels because of its
previous organic matter content. Loam is dark in colour and is mealy – soft,
dry and crumbly – in your hands. It has a tight hold on water and plant food,
but it drains well, and air moves freely between soil particles down to the
roots.
The feel test for loam yields a smooth, partly
gritty, partly sticky ball that crumbles easily. Although loamy soil is the
ideal material to work with, don’t despair if you don’t have it in your garden.
That’s because soil will always favour one particles size over the two others.
Then again, there are many ways to condition
your soil – adding beneficial soil inoculants, covering your soil with compost,
or simply spraying leaves and soil with compost tea.
Source: Wildlife & Environmental
Conservation Society of Zambia
Comments
Post a Comment