Is your fertilization program adapted to your crop? Find out how you do it.

In English literature we often read about 'micronutrient responsive crops' meaning how strong your crop responds to the treatments with trace elements. Had your crop to deal already with deficiencies, yellowing, slower growth or poor fruit size? Then it’s about time to check out how 'micronutrient responsive' your crop is. In other words, how sensitive your crop is for certain deficiencies?

If your crop is very sensitive to a certain nutrient, the reaction to a treatment with that element will be strong. We know the following ranking:

• very sensitive
• moderately sensitive
• little sensitive

Just an example

Imagine a field with a uniform soil fertility. On the one side we grow wheat, on the other side we have sugar beets.

When we look at the sensitivities for copper and boron, we see the following:

• Sugar beets are much more sensitive to boron deficiency than wheat
• Wheat is much more sensitive to copper deficiency than sugar beets

This means that sugar beets will react much faster and more strongly to boron applications than wheat and, on the contrary wheat will react much faster and more strongly to copper applications than sugar beets.

How do we explain this difference in sensitivity?

Some parameters that determine the crop sensitivities

• High need for a specific nutritional element

If a crop needs large amounts of a certain element, deficiencies will appear faster and more frequently during growth. As a result, the crop responds well to applications with this element.

In our example, sugar beets require about 3 times as much boron then wheat. Sugar beets are therefore more sensitive to this element.

• Temporarily high requirements for a nutrient

Sometimes the total needs of the crop are not that big at all, but they can be concentrated in a very short period. In this case, the plant must absorb relatively large amounts in a short time. This can cause stress and deficiencies, certainly if this coincides with other less favorable situations such as climate, soil conditions, …. the plant will not be able to absorb the nutrients sufficiently.

An example: Corn needs a relatively large amount of zinc during the first phases of its development. The period from germination until the plant has 4-8 leaves, often coincides with cold and humid periods making the absorption of zinc more difficult. This results in frequent deficiencies during this period. Applications of zinc will therefore have an effect on the development of the plant from early stages on, up to and including maturity resulting in higher yields.

• Efficiency of the roots

The roots also have an important role. Let’s have a look again at the example.

Sugar beets require more copper than wheat, yet a copper deficiency is not so common in sugar beets. This is because the roots of the sugar beets absorb and use the copper from the soil a lot more efficiently, avoiding so deficiencies. There might be a biochemical explanation for this difference in efficiency, but we do not always know how it exactly works.

Also in fruit production and viticulture, where rootstocks are frequently used, differences in the sensitivity of the different rootstocks for iron deficiency are well known. It is important to choose the right rootstock depending on the climate and the soil. This way you will avoid or reduce iron deficiencies. Research into these differences in sensitivity shows that rootstocks that are less sensitive to iron deficiency positively influence the root environment by their exudates. The iron in the soil around the roots becomes more soluble and therefore is easier to absorb. With a good and adapted choice of rootstock you will avoid or reduce iron deficiencies.

• The mobility of the element in the plant

The nutrient mobility is another important factor. If an element is more mobile in the plant, there is less chance that temporary deficiencies will occur during the growth cycle. Are you wondering why? It’s all about translocation.

• If an element is very mobile, the plant will easily move the nutrient internally from where it is less needed or in excess to where it is most needed. This prevents deficiencies, even in periods with reduced soil availability.
• On the contrary, when an element is little or not mobile, it settles after absorption somewhere within the plant and will no longer move. The plant will need to absorb new amounts to continue its growth and to nourish the new organs it is forming. If this element is temporarily less available in the soil, the plant might not absorb enough and will have a deficiency.

This phenomena can be observed with boron in different varieties of fruit trees. Fruit trees that are less sensitive to boron deficiency are varieties that can mobilize boron more easily within the plant by forming chelates with polyols. This way the boron can move from older leaves to the new growth. Deficiencies will therefore not get a chance.

How do you handle the sensitivities of your crop?

Keep an eye on the nutrients for which your crop is sensitive. They influence the productivity of your crop. Then check whether there are other factors that could influence the availability of these same elements such as soil conditions, climate, fertilization, etc…... Based on this information you can then decide whether or not it is necessary to supply extra amounts of this element. In this way you optimize the fertilization of your crop.

With our personalized nutrition programs, we have exactly the same goal in mind. Together with the advice from our technicians, we strive for your optimal result.

Example

Pear trees are very sensitive to iron.

• In slightly acidic sandy loam soils, the availability of iron is good to very good, and it will therefore be less (or not) necessary to supply extra iron even though the crop is sensitive for this nutrient, …. but
• In calcareous soils, with a high pH, the availability of iron is very limited and deficiencies in the pear trees will be very likely. In this case, our nutritional foliar program will provide extra iron in order avoid deficiencies and assure the productivity of your crop.

Do you know the sensitivities of your crop? Check your crop page and discover everything about the needs of your crop. Or contact us for a personalized advice.