As the fourth essential nutrient for crop growth, calcium’s importance to agricultural production is self-evident. It not only maintains the structural stability of cell walls, protects the integrity of cell membranes, and promotes root and stem development, but also significantly enhances crop photosynthesis efficiency and stress resistance. Therefore, calcium is essential for crop growth and development.
We know that calcium is slow to mobilize, so it needs to be applied early, ideally during base fertilizer application. Furthermore, calcium should not be mixed with potassium dihydrogen phosphate when spraying foliar fertilizers later, as this will create flocculent residues.
Therefore, if we want to apply potassium dihydrogen phosphate and calcium at the same time, we should choose sugar alcohol chelated calcium or EDTA chelated calcium. Some may ask, why is calcium chelated? Doesn’t it increase costs?
In fact, the main reasons for using sugar alcohol chelated calcium or EDTA chelated calcium are to address two issues.
The first issue is that calcium ions in the soil easily react with other ions to form precipitates, resulting in low utilization rates. Therefore, we need to find ways to improve calcium utilization.
The second problem is that calcium ions are very slow to move in the soil and within the plant body. So, we need to address this issue as well.
To improve calcium utilization and mobility, we need to incorporate other ingredients, which we call chelators. However, chelators aren’t chosen casually; they must meet two requirements.
The first requirement is that the chelator completely encapsulate the calcium. The second requirement is that it must be small enough to penetrate plant cells. This is easy to understand: if we encapsulate the calcium, it won’t react with other ions, improving utilization. However, if it’s too large to penetrate plant cells, it’s useless.
So, since both use chelators, what’s the difference between EDTA calcium and chelated calcium?
The chelator used in EDTA calcium is disodium ethylenediaminetetraacetic acid. We can see that this chelator contains sodium ions, which many crops dislike. Furthermore, its mass fraction is close to 400.
The chelating agents used in sugar alcohol chelated calcium are mannitol, sorbitol, or erythritol. These have a relatively small molecular weight, less than 200, half that of EDTA. Therefore, EDTA calcium has a higher chelating capacity than sugar alcohol calcium.
However, sugar alcohol calcium has an advantage that EDTA calcium lacks. Like glucose, it is a monosaccharide and can be directly absorbed by plant cells without clogging stomata. Furthermore, it lacks sodium ions, which are detrimental to plant growth.
In short, EDTA calcium has a stronger chelating capacity, while sugar alcohol calcium is more mobile. Both have their advantages and disadvantages.
How do we choose between them?
To be clear, both are excellent calcium fertilizers and can be very effective.
When applying foliar sprays, sugar alcohol chelated calcium can be used when mixing with other pesticides or fertilizers. However, when mixing with a large number of other ingredients, EDTA calcium is recommended due to its stronger chelating capacity, better compatibility, and greater safety. Do you understand?
