Sandy soil is not a priori ideal for gardening… but it can become.
We saw a while ago how to improve heavy clay soil.
Today let’s see how we can improve a light, sandy soil…
What are we talking about ?
What matters here is the soil texture, ie the composition in terms of mineral materials.
A soil that is predominantly sandy will have a sandy texture (or sand-loam if silt is also present in significant amounts), while a soil particularly rich in silt will have a loamy texture (or sand-loam, or loam-clay)…
Knowing this texture is essential in natural gardening.
Because from this we can determine the best way to make our land alive and fertile…
In My Natural Vegetable Garden I present you simple (and free) tests to determine with sufficient precision the texture of your soil (from the lightest to the heaviest: sandy, sandy-loamy, sandy-loamy, loamy, silty clay, clay silty or clayey).
Characteristics of sandy soil
Sand is a coarse material (a particle of sand is larger than a particle of clay or silt) whose elements will not clump together.
The predominantly sandy soils are light soils, which therefore heat up easily, and are therefore particularly suitable for early cultivation (the climate is of course essential).
This ability to properly heat up also promotes the breakdown of the organic matter deposited there.
They hold little water, so watering is done more often than on heavier soils.
Poor by nature, sandy soils also retain mineral elements (easily leached to the depths and therefore inaccessible to crops)…
For this reason, particularly abundant and regular contributions of different and varied organic substances will be required to improve fertility.
Often acidic, contributions from calcareous materials (wood ash, lithothamne, magnesium dolomite, etc.) are then welcome. But be careful, this is not a generality… there are sandy and calcareous soils (you will also find simple tests in My Natural Vegetable Garden to perform whether your soil is acidic, neutral or calcareous).
But now let’s see how we can improve the sandy soil sustainably and naturally (naturally…).
Regular additions of organic matter to enrich sandy soil
A light soil that retains few nutrients, regular additions of organic matter are highly recommended.
In order to promote the formation of a stable and durable humus, carbonaceous materials are preferred in sandy soil (which is good, because such soil, by its ability to warm up, allows good decomposition of this type of material … in contrast to clay soils, the degradation of which is strongly delayed).
In the fall
Let’s start with cow manure (by manure I mean a mixture of litter – usually straw – and manure; manure alone is not manure…).
It is a heavy material (more than horse manure) that will give this soil more body.
It is therefore especially useful on sandy soil (if not, horse manure is still welcome).
Regardless of the type of manure, large quantities (we are talking about amounts of around 100 to 300 kg per 100 m²), every autumn (not in the spring, because on the one hand the manure would not have time to decompose before the establishment of crops ; and on the other hand there are health risks…), will be very beneficial if your soil is light.
This manure will simply be spread on the ground (it can also, in a very superficial way, be integrated a few weeks after spreading…if you can…it will be all the more beneficial) covered with dead leaves, RCW , or even a little extra straw (especially if the manure is not very viscous).
In the absence of manure, you can also take compost (not necessarily broken down for an autumn supply) or even various green waste (last clippings, garden cleaning waste, kitchen scraps, etc.) that you cover with straw, dead leaves, RCW, or hay…
Do not hesitate to use different materials for the same mulch (it will promote the development of life).
In the spring and summer
In the spring, fast-setting materials (compost, composted manure, commercial organic manure, clippings, etc.) will be applied to feed the plants directly.
These contributions can be renewed during cultivation if the plants show signs of weakness, or to improve yields (even if comfrey will be more effective for this because of the faster effects).
Likewise, heavy mulching (more than eight inches thick, preferably with preferably carbonaceous materials* (straw, shredded material) once the soil has warmed sufficiently, will contribute to a long-term improvement of the soil (the breakdown of materials used to enrich of the soil) while limiting water loss through evaporation (and thus the frequency of watering).
*However, to promote the decomposition of the (hard) carbonaceous materials that make up the mulch, previous or additional contributions of green material (cuttings, nettles, comfrey, crop residues, vegetable kitchen waste, etc.) or, for example, old hay (start to digest , and thereby become unfit for animal consumption… breeders will gladly get rid of it!) are also welcome.
The ideal is a progressive mulch (as I specifically explain in this video).
Living mounds to get rid of a (too) light soil
Also for sandy soils, the creation of living mounds is a solution that can be considered, especially if it turns out to be particularly poor.
However, keep in mind that this requires the availability of various organic materials in very large quantities… and that this represents a significant amount of work to implement.
Clay to give more body to very sandy soils
A light, sandy bottom can also be improved by adding bentonite clay, in the form of powder or beads.
So in fact we will change the texture …
The soil retains mineral elements better and will dry out less.
This clay will also effectively contribute to the formation of a stable humus.
However, keep in mind that the costs are relatively significant.
No green manure on sandy soil…
For the development, a green manure will draw on the reserves of the soil…
However, these reserves are already low in sandy soils.
Also, except possibly if the soil is very compacted (in which case a crop of green manures can help loosen it), I don’t recommend growing green manures in this type of soil.
A sandy soil holds the water very poorly, regular watering and more often than in heavier soil is necessary.
As we have just seen, proper mulching helps reduce water evaporation.
This way you limit the chore of watering… which is particularly interesting here.
In the spring or autumn, preferably water in the morning, when the soil has already warmed up a bit (but the sun is not yet shining too brightly).
In the summer, no watering in the middle of the day… the water wouldn’t even have time to seep into the soil. In the middle of summer, it is best to give in the evening (the water then has all night to seep into the soil), at the base of the plants (so without wetting the leaves) or early in the morning (but the there is more loss than with watering in the evening).
If you have a drip irrigation system, place the channels under the mulch… watering will be all the more efficient.
To give you an idea, at home, in sandy-loamy soil and with very high summer temperatures, in mulched soil, for most crops, I water about once a week in mid-summer, but consistently (more details on the frequency of watering depends on the soil type, the vegetables grown, but also the stage of crop development, in Mon Potager au Naturel).
To comment on your keyboards, ask your questions, share your experiences or your experiments in sandy soil…