Basic Soil Types

soilWhen we embark on a landscaping project, it is essential that we know at least two things: what are the current problems in our garden that we want to improve, and what types of plants we’d like to raise. This is important because the distribution of the ground and the selection of the most appropriate soil for our cultures – whether we expect to eat from our garden or we simply wish to create a handsome and harmonious ensemble – will define the successful outcome of our plans, as plants are living organisms with specific needs.

Trees, shrubs or flowers, that we would never imagine growing and blooming in proximity in nature, may coexist in full glory in a residential garden. A sandy coastal backyard can be transformed into an all-green, highly productive vegetable garden, if we fill in large flower beds with rich loam soil. That piece of land by the fence wall, which used to gather stagnant waters, can host a number of graceful plants and flowers – all that needs be done is to perform a few simple tasks: excavate, lay gravel and/or other permeable materials for the effective drainage of the lot, fill in with soil, voilà!

After installing a good drainage system and after laying the substrate of our garden with materials that will help improve its functionality (e.g. gravel, geotextile, etc), it is time to lay the garden soil level and proceed to planting.

Garden Soil

By ‘garden soil’ we mean the topsoil, down to 24 inches deep, where plants sprout and grow. It is composed mainly of humus and mineral particles: clay (very fine grain), silt (medium-sized grain) and sand (large grain). The content percentage of the above mineral materials varies among different soil types.

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When adding topsoil, don’t just throw it on top of the ground.

Always incorporate some or all of it with the native soil,
or at least create a shallow transition zone between the two.

This way, water will be able to move freely across the newly created ground,
preventing the creation of soggy areas in the garden.

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How to tell apart the various soil types:

 

The simplest method is to pick up some soil when it’s moist and compress it.

  • Sandy soils will feel gritty
  • Loam soils will break apart into loose chunks
  • Clayey soils will cling together in a ball

Here are some quick, empirical and effective ways to diagnose your soil before proceeding to your landscaping and gardening plans: Soil Types and Testing

 

In the section below we will examine the most common soil types, their characteristics, how they respond to cultivation, and what we can do to improve them for greener and healthier gardens.

 

1. Sandy soil

It is light and fluffy, therefore very easy to cultivate, as it allows the soil to break up and be worked for planting. It also helps prevent crusting, which could block seeds from breaking the surface.

As sand is a quite loose material, it allows water, the sun and its beneficial spring warmth, as well as the air and oxygen to permeate more easily and in greater depth than other types of soil.

   Yarrow (Achillea millefolium) is a very useful
plant for preventing soil erosion due to its
resistance to drought. It also repels bad insects and
attracts good ones, while directly improving the
health of sick plants when grown near them.
Yarrow grows exceptionally well in well-drained
soils: sandy soils are ideal for the growth of this
valuable plant.

 

 

 

 

Downsides: Sandy soils

  • are not appropriate for plants with small root system, because their consistency does not allow for good support and the plants remain vulnerable to the force of the winds; furthermore, such plants will suffer during the hot season, when their tiny roots will be struggling to absorb scarce drops of water from a quickly drained ground;
  • as water and humidity are quickly drained, they carry along all the useful nutrients that get washed away, far from the topsoil where they are most needed.

Remedies:
We can improve our sandy soil significantly by mixing it with clay, manure or humus.

 

2. Clayey soil

It is very consistent, which makes it exceptionally hard to permeate by water, light and air. It keeps warm during winter, and retains water in the summer, but may crack deeply in high temperatures; when dry, you can feel how heavy and hard this material can be.

Downsides:
Due to its dense, compact nature, the roots of plants penetrate it with great difficulty and may suffocate from inadequate airing. During droughts, when superficial humidity evaporates, the plants cease to grow, sometimes even shrivel.

Remedies:
We can improve clay by mixing in sandy soil, manure or humus.

 

3. Chalky soil

Echinacea, sought for its valuable properties in curing common colds, thrives in lime-rich soils.

Echinacea, sought for its valuable properties in curing common colds, thrives in lime-rich soils.

 

It comes from calcareous (lime-rich) soils and therefore very alkaline.

Downsides:
Most chalky soils are shallow, free-draining and poor in nutrients; however, when clay is present, nutrient levels may be higher and water holding capacity better. On the other hand, the high alkalinity of the ground will still prevent the absorption of iron by the plants.

Remedies:
Mix in sand and/or manure. Avoid limestone and dolomite, as they will increase the soil’s alkaline content.

 

4. Loam soil

Dark brown or black, it contains almost equal amounts of sand, silt and clay (40-40-20 %). It is outstanding for cultivation, as it is rich in nutrients and humus, retains the necessary amounts of water while at the same time allowing excess water to drain away, and it is easier to till than clayey soils.

Loam soil keeps relatively warm during the harsh winter days, while it doesn’t bake in the fiery summer. It also promotes the growth of beneficial microorganisms which help keep the soil healthy.

Loam soil is the gardener’s friend: a rich, healthy topsoil which, of course, still needs good management, so as not to get depleted and impoverished. Working in organic materials from time to time will keep the soil in good condition. We can also use it to enrich poor soils (clayey, sandy and chalky).

 

5. Silt soil

It is similar to loam soil, but contains smaller ratios of both sand and clay particles. Silt is the material deposited in river banks and floodplains and, therefore, it is very fertile ground. It holds water, like clayey soils do, yet it drains much better.

The lovely weeping willow’s natural habitat is river and lake banks — silt soils are just right for her.

Downsides:
Silt soils tend to erode easily, as their fine, light particles are blown away by wind and carried down by water streams. They also tend to get compacted easily — avoid walking on flower beds and prefer to use pathways, such as narrow boards, between beds and plots, or build raised beds.

Remedies:
Mix in mulches, sand and/or other drainage assistance materials.

 

Image sources: Baby seedlingEchinacea, Yarrow, Weeping willow

The Eco-friendly Garden

We don’t really need to go to the movies or walk into dark alleys at night in order to live moments of horror and agony: a garden can perfectly well make our weekend an unforgettable experience – which is not always pleasant…

Just remember how many times you have seen or heard of a child presenting serious allergy symptoms after rolling on a lawn and coming in touch with recently applied chemical fertilizers, pesticides or insecticides…

This, of course, does not mean that we can’t enjoy a lush, green garden when we have small children roaming around our yard. Turning to a more eco-friendly gardening model will protect the health of our beloved ones, while helping our garden to be and to look healthier.

 

Gardens, even in their primitive wild condition, were present on Earth long before humans made their first steps on the planet.

 

After billions of years of evolution, the flora of a place, in combination with the fauna living in it (birds, insects, worms, snails, etc), can form a complete local ecosystem.

Much like a human or animal body, this ecosystem has its own particular workings going on, and a sensitive balance that needs to be maintained, so that it remains healthy and robust.

 

A garden is an islet of life, a unique orchestration of natural elements (ground, weather) and of the living creatures (fauna, humans) thriving in those very specific conditions.

 

Nature has its own ways of preventing and of curing diseases, of keeping away harmful species and of expelling anything unfit to live in a given environment – whether you wish to have it embellishing your garden, like that jasmine you like so much (alas! in those chilly Minnesota nights), or you would love to see it vanish from your garden, like that horrid aphid which dries the sap out of your beauties.

Naturally Balanced Landscape Design

The ground contains, naturally, an array of nutritional substances.

Besides being indispensable to the plants themselves, a landscape design which has an exchange of substances, liquids and saps from and within the environment of an ecosystem, such as your garden, is a vital process for the fauna of the area as well. And we all know how insects, earthworms and other useful species perform many necessary functions (pollination, praying upon harmful species, airing and enriching of the ground, etc).

It is important that plants receive the substances appropriate to their own specific nutritional needs and that they avoid soils and adjacency with plants that are not beneficial to them.

If you ever grew a vegetable garden, you must have noticed how green peas hate the company of tomatoes; on the other hand, they are nitrogen-generating plants: your Brussels sprouts, or your ornamental leafy vegetables will be grateful for being planted on a spot previously occupied by green peas. This information can be very useful in the practice of crop rotation.

Even during the life cycle of an individual plant, its nutritional needs may vary according to its reproductive stage: as a general rule, nitrogen helps increase the sprouting of shoots and leaves, while phosphorus assists blooming and fruit-bearing.

The lack of or, on the contrary, the overexposure to a certain nutrient may cause chain reactions, harmful to your plants. For example, the imbalances in calcium supply (an absolutely necessary substance for the delivery of nutrients and for regulating the soil’s acidity (pH), leads to lack of phosphorus – which, as we already saw, assists fruit-bearing.

This will result in a poor crop; additionally, the leaves will take on an auburn hue.

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Tip: Do not place plants with similar nutritional needs together, as they will be constantly rivaling each other.

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Besides absorbing substances from the ground and from their leaves, plants also secrete them. Plants contain essential oils, resins and other kinds of liquids – even in minimal amounts – that may attract or repel animals and other plants. Some examples:

  • basil, ocimum basilicum, repels flies and cucumber mildew;
  • wormwood, artemisia absinthium, repels worms, greenflies, ants, cabbage butterfly, and more;
  • elderberry, sampucus nigra, whose flowers attract bees and fruits attract several bird species;
  • stinging nettle, urtica dioica and urtica urens, that should be in every garden, as it is needed for the reproductive cycle of more than a hundred different kinds of useful mites, and also boosts production for neighboring plants, while increasing the production of essential oils of the herbs growing next to it;
  • garlic, allium sativum, a potent anti-fungal which can be planted near or around fruit-bearing trees, rose bushes, and vegetables (except beans, cauliflowers, cabbages, broccoli); it also assists the growth of strawberry plants.

It is important to have a combination of plants mutually profitable for each other: your garden will be much healthier, more balanced, and your plants will grow showing off all the splendor of their natural beauty.

Beneficial Insects

Pest control can rely heavily on the beneficial insects living in your garden: if you care to provide them with appropriate living conditions (the plants from which they harvest pollen and nectar, poison-free environment, a hiding place, such a little pond, a loose stone wall, or a tuft of wild grass) they will multiply unimpeded and they will start their campaign against the larvae and the adult insects that usually attack plants.

Beneficial insects are real predatory warriors that go hunting or ambush a variety of common gardener’s headaches. The best way to attract them to your garden is to designate a space (about 5-10 per cent of the total area) in which you will grow wild and domesticated plants and herbs that beneficials love to visit.

Applied in a larger scale (e.g. a farm) the concept is called farmscaping and it is a scientific method of biological control that will allow nature to regulate itself without the use of detrimental chemical agents.

Ladybugs, praying mantises, and lacewings larvae are some of your best allies in keeping pests under control, and they are really easy to find:

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Images courtesy of: Touching the Tulip, Sunflower, Lavender & Ladybug