How To Turn Clay Soil Into Good Soil

A clay soil is a very compact and not very transpiring soil in which the root system of plants develops poorly.

Heavy clay soil
Heavy clay soil: how to improve it

How to recognize a clay soil

In clayey soils the percentage of clay is 35% or more.

If you try to turn over a clod of soil with a spade you will notice that the color of the soil tends to light grey and shiny, when it is humid, and the clod remains compact and does not crumble as it would happen with a sandy soil or one rich in humus.

This happens because the particles that make up the soil weld together thus preventing water from draining away.

A claysoil, after a violent downpour, turns into a marsh if there is no slope and the water has no way to flow away. When the water finally dries we will notice that a compact crust has formed that tends to crack under the beating sun.

These are extreme conditions in which crops, especially horticultural ones, can hardly survive.

Digging a clayey soil by hand is really tiring and it must be done when the climate, and therefore also the soil, is dry if we do not want to ruin our backs.

An empirical system to check the draining capacity of the soil can be put into practice by digging a hole 60 centimeters deep and then filling it with water.

If the drainage is acceptable, the water tends to be absorbed and disappear within 24 hours, but if it stagnates in the hole for 48 hours or more, then we will be sure that this type of soil tends to be clayey and that its structure needs to be improved if we want to successfully cultivate our garden plants and/or vegetables.

How to improve heavy clay soil

Often, improvement of clay-rich soils occurs gradually, over the course of several seasons.

In the case of planting a new garden, we should not expect immediate solutions unless we intervene massively (and quite expensively) on the composition of the soil.

A possible and quick alternative is to create a raised bed garden (in case it is a vegetable garden) by which the obstacle of heavy soil is circumvented by cultivating inside a raised bed where fertile and light soil has been added.

Digging of a clay soil must necessarily take place in autumn, so that during the winter the compacted clods have the opportunity to slowly disintegrate.

The opposite of a clay soil is a stony, sandy soil.

While water tends to pool in clay soil, water tends to be absorbed too quickly in sandy soil.

In both cases these soils need to be improved and their different behavior can suggest how to improve heavy clay soil because, as the Latins said, virtue lies in the middle.

Clay soils can be improved by modifying their physical structure with the addition of organic material such as manure, garden soil, peat, decomposed leaves, and also inorganic material such as sand, ash and agricultural gypsum.

Agricultural gypsum should be purchased from agricultural consortia since what can be found at construction stores does not have characteristics suitable for the purpose.

As a general rule, one basket of organic material and two baskets of inorganic material should be spread for each square meter of soil.

The addition of agricultural gypsum should be done in the amount of 250 grams per square meter.

If the soil is very acidic, a strong amount of lime can make the clay more porous, thus facilitating the union of soil particles into small lumps.

Working in this way also encourages the proliferation of earthworms which, although slowly, will contribute to improving the characteristics of the soil, helping to increase its permeability thanks to the tunnels they dig.

The sand that is added must be coarse-grained and, even better, mixed with gravel.

The addition of material, both organic and inorganic, must be done after spading or plowing and then, in spring, the soil can be mixed and broken up by means of a rotary tiller.

The important thing is that the material added to improve the characteristics of the clay soil is not buried too deep in order not to nullify, in whole or in part, the work made.

DIY Editor
Do-it-yourself enthusiast. I started with the renovation of my flat and then I changhed this passion into my job.