Structural stability of soil

Organic matter autonomy in vegetable farming Soil cover Soil regeneration

Structural stability is a physical property of soil. It is defined as the ability of soil aggregates to resist the degrading action of rainfall.

It depends on:

Clay content: the more clay in the soil, the more stable it is.
Organic matter content: the more organic matter in a soil, the more stable it is.
Ionic composition: calcium (Ca2+) stabilizes aggregates, whereas sodium (Na+) tends to destabilize them.

How to test the structural stability of a soil?

A test was developed by INRA in Orléans. It allows measuring the physical behavior of a soil subjected to rainfall action, and thus its sensitivity to the formation of a crust. This method, standardized by Afnor since 2005 (NF X31-515), has become an international ISO standard since 2012 (ISO 10930-2012 "Soil quality - Measurement of the stability of soil aggregates subjected to water action").

To learn more about this method:

What are the levers to increase the structural stability of a soil?

Establishing a cover crop will help structure the soil during vegetation and increase its resistance to erosion thanks to rooting.

Ensuring a good organic matter content in the soil because it improves soil structure, porosity, and chemical fertility.

Promoting biological activity. Soil organisms play a crucial role in soil structure.

By digging galleries, earthworms create a true aeration network. Their mixing action also favors deep circulation of air and water.

Fungi secrete glomalin (a glycoprotein) which has an important aggregation function. This increases the retention of organic carbon, water, and minerals by the aggregates.

Conservation tillage techniques promote the development of microfauna, notably earthworms, which improve soil structure and loosen the soil on behalf of the farmer. These techniques avoid exporting mineral nutrients contained in straw and contribute to system sustainability.

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