For over 60 years, soil analysis has been used to guide the fertilisation of land and crops.
With growing environmental concerns and rising prices of mineral fertilisers, fertilisation practices now need to evolve.
This starts with new indicators of soil fertilising value.
The soil-as-a-support approach
Within a “soil-as-a-support” logic, all crop requirements are supplied through mineral fertilisers, without taking existing soil reserves into account.
This approach involves saturating the plant’s rooting capacity. In this case, a potassium/magnesium (K/Mg) ratio > 3 is required.
This approach, used since the 1950s, places fertilisers at the heart of the cropping strategy.
From an economic perspective, this approach is becoming unsustainable in the context of rising fertiliser prices. From a technical standpoint, it weakens soil structure.
Indeed, potassium (K⁺) binds to the clay–humus complex in place of Ca²⁺ and Mg²⁺ (base cations), which damages soil microstructure and increases compaction and surface crusting.
The living soil approach
Within the “living soil” approach, nutrient stocks originating from the soil and the parent material are considered sufficient to meet crop requirements.
Provided that these “locked” nutrients become “available”.
This approach places soil biological life at the centre of crop management.
For this approach to allow soils to express their full potential, sufficient organic matter (OM content) and a structure favourable to air presence at depth are required (Mg/K ratio > 1).
Monitoring magnesium (Mg) is particularly relevant due to its dual role: on soil structure (like Ca²⁺) and its essential function in root nutrient uptake.
This approach is far more sustainable and economically more attractive.
However, it requires changes in established soil management habits.
Final thoughts
The transition from a “soil-as-a-support” approach to a “living soil” approach is now a key step.
This transition must be prepared by monitoring new indicators (such as the Mg/K ratio) and by adopting a comprehensive management approach: tillage, crop rotation, organic manuring, fertilisation and amendments, in order to gradually remove the key limiting factors.
For over 60 years, soil analysis has been used to guide the fertilisation of land and crops. With growing environmental concerns and rising prices of mineral fertilisers, fertilisation practices now need to evolve. This starts with new indicators of soil fertilising value. CONTENTS The soil-as-a-support approach The living soil approach Final thoughts The soil-as-a-support approach […]
...For over 60 years, soil analysis has been used to guide the fertilisation of land and crops. With growing environmental concerns and rising prices of mineral fertilisers, fertilisation practices now need to evolve. This starts with new indicators of soil fertilising value. CONTENTS The soil-as-a-support approach The living soil approach Final thoughts The soil-as-a-support approach […]
...For over 60 years, soil analysis has been used to guide the fertilisation of land and crops. With growing environmental concerns and rising prices of mineral fertilisers, fertilisation practices now need to evolve. This starts with new indicators of soil fertilising value. CONTENTS The soil-as-a-support approach The living soil approach Final thoughts The soil-as-a-support approach […]
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