Calcium and the plant — what does soil liming do and how does it affect yield?
Soil liming is a key agronomic practice that has a major influence on plant health from germination all the way to harvest. Calcium acts as a building block of cell walls and takes part in regulating the plant's water balance. On strongly acidified soils, liming can increase maize yield by as much as several dozen percent, and oilseed rape by around 15%. Without properly regulated pH, the effectiveness of NPK fertilisation is clearly limited.
Acidic soil and toxic aluminium (Al³⁺)
Most of the problems that farmers attribute to drought or disease actually originate in soil acidity. When pH falls below 5.0, toxic aluminium (Al³⁺) is released into the soil. It is lethal to young roots — it destroys their growing tips, leaving them short, thickened and unable to draw water from deeper layers.
In addition, an acidic environment causes a chemical "lock-up" of phosphorus, which becomes unavailable to the plant. The result is so-called "hidden hunger", where the plant fails to grow despite intensive mineral fertilisation, and yields are drastically lower than their potential.
The effect of calcium on plants
Bluebird products deliver calcium in a highly reactive form, which triggers key physiological processes:
- Stabilisation of cell walls — calcium forms calcium pectate that acts like "cement", providing tissue firmness and resistance to lodging and pathogens.
- Stress signalling — Ca²⁺ ions help the plant respond to drought by controlling the stomata.
- Aluminium neutralisation — raising the pH precipitates toxic aluminium into harmless forms, opening the way for root development.
How to fully unlock the potential of liming?
- Gravity principle — granulated lime is best spread on the surface, onto a levelled field; it should not be ploughed in deeply.
- Timing — best in autumn after harvest; the safe granulated form also allows for corrective top-dressing liming in spring.
- Split doses — on light soils it is better to apply smaller doses (500–1000 kg/ha) more frequently, protecting the soil microflora.