All You Need To Know About Silty Soil

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Silty Soil: Silt, one of the 3 basic soils, is composed of rock and mineral particles and it’s commonly found along with clay, sand, gravel, and other sediments. Larger than clay but smaller than sand, silt particles are less than 0.005 cm in diameter – making them very hard for the naked eye to see.

If you think your garden soil is silty, you’ve got some fertile ground to work with.

                                                       PROPERTIES
It takes the forces of nature – water, wind, and ice – and a very long time to erode rocks and create silt. Flowing water serves as a vehicle for tiny bits and pieces of rock that scrape against the bottom and sides of stream beds, further fragmenting the small pieces of rock.

The rock particles bump and grind against each other, eventually resulting to very small bits that we call silt. Wind, on the other hand, can carry tiny bits of rock across landscapes – grinding against rough surfaces until the particles get smaller and smaller.Silty Soil

One may think that silty soil should feel rocky when wet. After all, the soil came from rocks! But that isn’t the case:

silty ground feels slippery and even soapy when wet, not grainy.

Soils that contain more than 80% silt are not very common in gardens, and a gardener would be worried if his soil’s silt content is off the roof. For starters, silty soil can be easily compacted through constant foot traffic and use of gardening equipment, leading to low air infiltration, stifled root growth, and other problems. Moreover, soils rich in silt content can be easily washed and blown away especially when there are no plants to help weather the elements and keep the ground together.

But don’t get this wrong: silty soil has its share of redeeming qualities you shouldn’t ignore.

The water retention and air circulation in properly maintained silty grounds are way better than those of sandy soils, allowing silty soils to hold more nutrients and making it more fertile than other soil types.

It’s of little surprise that agriculture thrives in areas surrounding river deltas and other bodies of water where silt abounds. Just take Nile River Delta as an example – a great spot for farmers for thousands of years and counting.

READ MORE: All You Need To Know About Clay Soil

PREPARATION
Silty soil has its own disadvantages like sandy and clay soils, and properly preparing the soil before planting is a must to successfully garden in it. But before we look at the things we should do, let’s look at the things you should avoid doing at all costs. Here they are:

Compaction: Silt particles are fine. They may not be as fine as clay’s but they’re prone to compaction all the same when not worked on properly.

Foot traffic can cause the soil to get dense and tighten up, preventing air circulation and suffocating plants’ roots. If your garden soil is rich in silt particles, consider using narrow boards as pathways for your beds, which you can stay and walk on as you tend to your plants.

This minimises walking or treading, one of the most common causes of soil compaction. You can also garden on raised beds, ensuring that you don’t step on your soil.

Overwatering: Silty soil’s high water retention is due to the numerous air spaces that can pool or store water. It sounds nice but it’s also the reason why silty soil is prone to waterlogging like clay soil.

You should be careful not to overwater your garden if you are to succeed in gardening with silty soil. Overwatering silty soil can result to clogged air pockets – taking away breathing space and choking the roots. This can result to rotting roots that are brown, black, or grey in colour.

Damaged and rotting, these roots are unable to absorb nutrients that are necessary for survival. If your plants are suffering from wilted foliage and light green leaves, you are watering your plants too much.

Worse, rehabilitating waterlogged silty soils – while doable – can take a very long time!

On the other hand, there’s the flip side of the coin – not watering your plants adequately and that is just as problematic. Watering too lightly results in underdeveloped roots that don’t bury deep enough.

The plants then have to compete with grass and weeds whose short roots are built for getting water near the surface soil. Furthermore, plants with shallow roots are weaker against drought.

Fortunately, you can easily tell when to water your ground by taking a pinch of the topsoil. If it’s dry to the touch, watering your garden is in order.

So that’s it: compaction and overwatering are big no-no’s for every soil type but especially for silty soils so always keep that in mind when working on your garden.

Moving forward, let’s now take a look at how to prepare silt-rich soil for planting and gardening – starting with testing the soil.

READ MORE: All You Need To Know About Peaty Soil

Running a soil test isn’t a must but it can give you a better start in gardening – giving you valuable information about your soil that you won’t find by simply touching, looking, and smelling at it. While soils can be categorised, their pH readings as well as amount of organic matter and nutrients (nitrogen, potassium, phosphorus, etc.) vary from one another.

There are universities and establishments that offer soil tests for a price. It’s highly recommended to pick soil samples from different areas of your garden – especially in those spots you intend to plant on – to achieve best results.

A good soil test will give you very specific information about your soil – chemistry, pH levels, nutrient content, etc. Some soil test providers even provide detailed nutrient recommendations for plants and suggested steps for enhancing the soil.

Recommendations and suggested improvements in the soil test report vary, but adding organic matter is necessary for keeping any soil healthy. For silty soils however, you want to apply organic matter that also helps improve soil aeriation and drainage, minimising the risk of waterlogging.

Organic material like thoroughly decayed sawdust, composted vegetable matter and manure, as well as ground pine bark are good candidates. Start by applying a 2- to 4-inch layer of organic matter on your garden and knead it into the ground at a depth of 8 to 12 inches, the common root zone for garden plants.

You should also consider infusing the soil with organic fertiliser for better plant nutrition. Adding 2 to 3 inches of mulch on top of your soil is also a good idea, preventing erosion, weed invasion, and drought stress.

Silty loam soils are known for being slightly acidic. Now, you may have sworn against applying anything inorganic to your garden. But if you’re fine with adding lime and dolomite, it can help balance the pH of silty soil. Keep in mind, however, that it can have adverse effects when applied recklessly.

Lime and dolomite can add up in the soil – raising the pH beyond the ideal level for plants. Don’t play “hit and miss” with this step. If you want to add inorganic amendments to your garden, it’s wise to stick to the recommended application rate in your soil test report.

Remember: keeping your silty garden soil healthy is always a “work in progress.” Maintaining your soil’s health through regular application of mulch and organic matter, ideally twice a year, helps optimise nutrient cycling and maintain soil temperature. Mulch breaks down eventually but its work doesn’t stop there. Organic mulch will decompose eventually – and that can only benefit your garden soil.

                                                    PROS AND CONS
What’s Nice About Silty Soil
Silty soil is generally more fertile than other types of soil (ex.: sandy soil). Its particles are a tad larger than clay’s but smaller than sand’s. This allow silt-rich soils to hold retain water and nutrients better than sand, but be a little better than clay soil when it comes to draining.

A garden with silty soil can support a wide range of plants. Agriculture thrives in river estuaries and deltas – areas with high silt content that experience annual flooding, replacing soil particles which aids in water retention and aeriation. The fine silt particles are washed and deposited downstream – slowing down the flow of water for plants to absorb.

Moreover, species thrive in silty soil especially when the ground is regularly amended and fed with organic matter (compost, mulch, etc.) These microscopic organisms are essential for a garden’s health as they are responsible for breaking down organic matter. Certain soil bacteria even release antibiotic to combat pathogens in the soil.

What’s NOT So Nice About Silty Soil
While silt-rich soil is more fertile than other soil types, it does have its share of disadvantages.

If you are to grab a handful of silty soil, you may notice that it can form a cohesive ball but it’s not possible to mold it like clay. Nevertheless, waterlogging is one of silty soil’s biggest problems, just like clay soils. Overwatering is a real risk so be sure to check the ground before watering your garden.

Silty soils are also prone to becoming heavier and colder when exposed to constant pressure – becoming poorly drained although not as terrible as clay soils since silt warms up quicker. Still, that’s one issue a gardener should pay attention to.

                                                               PLANTS

YELLOW IRIS
The yellow iris – those that are grown in wet areas – boast a bouquet of yellow blooms.This flower, scientifically named “Iris pseudacorus,” usually flourishes in the wild especially near the shallow regions of ponds and lakes. However, it can also grow in home gardens and more so in soils that are rich in nutrients and moist.

SWAMP MILKWEED
Want to attract monarch butterflies and hummingbirds to your garden? Consider growing swamp milkweed. This showy plant flourishes easily in fine, well-watered silty soil. It produces nectar-rich pink and red blooms during spring and summer that butterflies and hummingbirds love.

RED CHOKEBERRY
It’s an upright shrub that can keep your garden looking great during fall with its foliage and glossy red berries, and in spring too when it teems with white flowers. It easily grows even in not-so-ideal conditions and has a wide range of soil tolerance.

SUMMERSWEET CLETHRA
“Clethraalnifolia” is a versatile plant, able to adapt to the environment it’s in and tolerates full sun. However, it grows best under partial shade and in soils that are consistently moist. As long as you keep your soil from drying out, the Summersweetclethra will do just fine and will reward you with clusters of dainty white flowers.

AMERICAN ELDER
If you love jellies, jams, and wine, you may want to grow American elder as its elderberries have so many culinary uses including those just mentioned. It doesn’t mind growing in average, medium-to-wet, well-drained soils and can handle full sun to part shade. For best results however, keep your soil moist and rich in organic matter / humus.

WEEPING WILLOWS
Wet and hard-to-plant areas might prove problematic for other trees, but not for the weeping willow. This tree can grow in just about any soil, although moist areas like those surrounding a pound are preferable. Whether you’re looking for shade or some strong, pliable material for arts and crafts, the weeping willow’s long limbs will prove useful.

BALD CYPRESS
The bald cypress is a deciduous conifer that thrives on saturated, silty loam soils as well as well-drained clay soils. This tree – which can prove to be a fine specimen in a garden with the right soil and care –can adapt to both dry and wet conditions and can survive flooding.

NEW ZEALAND FLAX
Boasting colourful and strappy leaves, the New Zealand flax adds that tropical, lighthearted feel to your garden. This plant also exhibits flexibility and adaptability. While it will look spectacular when planted directly in your garden soil, you can also plant them in containers if the situation calls for it.