Iron fertilizer: application & effect of iron sulphate

Iron as a nutrient is mainly needed for the formation of enzymes. Here's how iron fertilizer is applied and if it's toxic.

Not only humans can suffer from iron deficiency, plants can also lack this trace element. In this case, fertilization with iron is necessary. We see iron deficiency through headaches, fatigue, brittle nails and many other symptoms. But how do we now recognize in our plants whether they lack iron and whether we need to help with some fertilizer? We provide you with the answer to this question here, as well as further information on the subject of iron fertilization.

Before we go into more detail about the use of iron fertilizer and how it works, it is important to understand what properties iron has and why our plants need iron.

Properties of iron at a glance

Iron is an important part of our life. It is used as a building material in our homes and even our breakfast juice is enriched with iron. But we can also find iron on the periodic table, under the element symbol feet, from the Latin designation iron derived. Iron is a heavy metal, available as either divalent or trivalent iron (Fe²⁺ or Fe³⁺) or in compounds (oxides, salts). For our plants is only the Fe²⁺ interesting, because they can absorb this and feed on it. the fe³⁺ is not directly available for the plants. The bound iron can be released from the different minerals by weathering. Iron ions are released during this weathering, but several factors affect the availability of iron, such as pH and humidity. Moist soil with a pH of 6 to 6.5 usually contains a large amount of Fe²⁺. If the pH value rises above 6.5 and you also have to contend with drought, this availability decreases more and more. The iron is bound and is then no longer available to the plant.

Why do plants need iron?

While iron is not a direct component of the green leaf (chlorophyll) responsible for photosynthesis, it plays an important role in its formation. It acts as a catalyst, which means it accelerates and supports the formation of green leaves.

Iron has another important task in the respiration of plants, more precisely in connection with the respiratory chain. The respiratory chain is part of the energy metabolism. Here, energy is generated from the absorbed nutrients - an extremely important process for all living beings. Iron is often also a component of various enzymes that play different roles in metabolism. the fe³⁺ is not directly available for the plants, because it has to be converted into Fe in the soil²⁺ be converted or chelated. Plants can only Fe²⁺ or chelated Fe³⁺ take up. Chelates are complexes that can be taken up by plants as whole molecules. The word "chelate" comes from the Greek chele and means something like claw or crab claw - and that also describes what chelates are. At the center of a chelate is an ion, often a heavy metal like iron. Larger organic molecules cling to this and hold it tight. These compounds are very stable, nutrients can be more easily absorbed by the plant as a chelate.

Recognize iron deficiency in plants

How does an iron deficiency show up in our plants? One symptom of iron deficiency is leaves turning yellow while the veins remain green - this is called chlorosis. These chloroses form first on the young leaves. As the deficiency increases, necrosis (dying tissue) forms from the edge of the leaf. When an iron deficiency occurs, there is also a lack of chlorophyll, protein and energy. Therefore, the growth as well as the yield of the plant decreases. Flowers can also fade in color and remain smaller overall. With an iron deficiency, the roots are usually short and have many short side roots. If the iron deficiency is not treated, your plants can even die - but only if the deficiency is severe.

Iron deficiency is often found on calcareous soils in particular, because iron is precipitated there by the calcium carbonate present there. As a result, the iron can no longer be absorbed. Some plants can already show what soil they are growing on - for example, soils on which a lot of coltsfoot, nettles or dandelions grow are often rich in lime. More information about chlorosis we have also compiled this for you in a special article.

Summary signs of iron deficiency in plants:

• Presence of chlorosis with leaf veins remaining green
• Signs appear first on the young leaves
• Necrosis occurs later, starting from the leaf edge
• Inhibited growth
• Low yield
• Pale, small flowers
• Occurrence of short roots and many lateral roots

Drought and compaction can also be reasons why the plant cannot absorb iron. It is therefore worth watering the plants properly after a long drought. Waterlogged and compacted soil can also be a hindrance to the iron absorption of the plants. Such soils often inhibit root growth and there is a lack of oxygen or at the same time an excess of carbon dioxide. Mechanical loosening and the incorporation of primarily organic fertilizers like ours Plantura organic fertilizers can put an end to compaction.

Another important factor that provokes iron deficiency is the excess of others heavy metals in the soil. The transport and uptake of iron can be inhibited if there are many ions of chromium, copper, cobalt, zinc, manganese or nickel in the soil. Bark humus can contain a lot of manganese and an excess of zinc in particular can lead to an iron deficiency.

In general, one can say that problems must be expected as soon as the balance of the ions in the soil is disturbed. The interaction of iron and phosphorus is particularly interesting. When there is a lot of phosphorus in the soil, it is possible for these two nutrients to combine and form ferric phosphate. We know this compound as slug pellets, but it can also form in the soil and thus bind the nutrients.

Here we have briefly listed the iron deficiency triggers again:

• Too high pH
• waterlogging
• dryness
• Inhibited root growth
• Imbalance and excess of other nutrients
• High phosphorus content

Apply iron fertilizer correctly

If your plants are now affected by an iron deficiency, there are various ways to supply them with it. Since iron can be absorbed through the roots and leaves, you have several possible uses.

Iron foliar fertilization

Iron can not only be fertilized via the soil, but also as a foliar fertilizer. The advantage of foliar fertilization is that it takes effect very quickly. Since the fertilizer is not introduced into the soil, it cannot be washed out and is effective despite dry soil. However, foliar fertilization can only be used at a low concentration to avoid damage to the leaves.

This form of fertilization also has to be used more frequently and the fertilizers are unfortunately somewhat more expensive than other iron fertilizers. It is also possible to use iron fertilizer regularly as a preventive measure and thus counteract deficiency symptoms. But always stick to the product description and the recommended doses. When using iron fertilizers, it is also important not to apply them in blazing sun and at temperatures above 25 °C - this can damage the plants.

Iron fertilizer in the irrigation water

You can also add iron with the irrigation water. To do this, dissolve the iron fertilizer in the irrigation water according to the product description and add it to the plants. In the irrigation water, an amount of 1 to 2 mg iron per liter of water is sufficient for proper iron fertilization. Then rinse the watering can thoroughly to remove any product residue. Also, be careful not to stain the floor or your clothes with the iron fertilizer. This results in unsightly rust stains that are either difficult or impossible to remove.

Which plants are often affected by iron deficiency?

To put it simply, cultures that consume a lot are often affected. ornamental plants like roses (pink), hydrangeas (Hydrangea), magnolias (magnolia) and Rhododendrons suffer particularly often. Fertilizers for rhododendrons and roses often contain a small amount of iron to prevent chlorosis due to iron deficiency. Even heavy consumers of vegetables such as tomatoes (Solanum lycopersicum), cucumbers (Cucumis sativus) and paprika (capsicum) are struggling with the lack of iron.

With fruit you often find one with berries, apples (penalty) and quinces (Cydonia oblonga). The flower lovers among you who like petunias (petunia) on the balcony will certainly have been confronted with an iron deficiency at some point. If chlorosis occurs in petunias, it is usually due to an iron deficiency. More about one Chlorosis in Petunias you can also find out here.

Iron fertilizer for lawns and against moss

Even your favorite green lawn can suffer from iron deficiency. This is mostly caused by the soil conditions. Some soils contain more iron, others less. But to be absolutely sure, you can carry out a soil test. One way of using iron fertilizer on the lawn is to combat unwanted moss. If your lawn is heavily covered with moss, you can treat the damp moss with iron fertilizer. Before doing so, you should mow the lawn to a length of about 3 to 4 cm and then treat the moss with iron fertilizer (ferrous (II) sulfate). Iron fertilizer can be used either as granules or, as already described, mixed into the irrigation water as a liquid fertilizer. The application should be done in spring in March or April, if the ground has already completely thawed. The moss then dies off after about two weeks and turns brownish to black. You can then simply remove the moss with a rake or rake. It is particularly important that you fill in the gaps left by the moss.

After the removal you should come back sow grass, so that no other weeds or moss settle. If you remove this moss in the spring, this is ideal so that the reseeding can take root. Do not walk on the lawn for about two weeks after applying iron fertilizers. Also keep your pets away from the lawns - they could lead to poisoning. What else you against moss in the lawn can do, you can find out here in our special article.

We recommend that you always provide your lawn with sufficient nutrients and primarily use organic slow-release fertilizers like ours Plantura organic lawn fertilizer to put. This not only makes your lawn fit and lush green, but also protects the soil and you can always step on your lawn again immediately after fertilization. More information about our Organic Lawn Fertilizer you'll find here.

Iron fertilizer for aquariums

Aquarium plants also need nutrients, because if the plants show chlorosis, they are also lacking in iron. The fact that the first commercially available aquarium fertilizer was iron fertilizer shows that an iron deficiency in the aquarium is not that rare. A general quantity recommendation cannot be given for the application. Each aquarium is individual in terms of filling quantity, filter systems, stocking, feeding and planting. An optimal iron content in an aquarium is 0.03 to 0.1 mg/l. This can be easily checked with test strips from the pet shop. Another indicator of sufficient iron content is the growth of duckweed. If you have duckweed in the aquarium and enough iron, then the lentils will reproduce well. If there is a lack of iron, the duckweed will stop growing. Unfortunately, fertilization in the aquarium - no matter which nutrient is involved - is often associated with the formation of algae. You should therefore be very careful with the dosage and fertilize a little less than too much.

Is iron fertilizer toxic?

In general, iron fertilizers are toxic and you should always avoid physical contact with these fertilizers. Wash your hands thoroughly if you have come into contact with it. If you have symptoms after contact with iron fertilizer, you should definitely consult a doctor.

But it is not only the toxicity that needs to be considered, but also the unsightly stains that the iron fertilizer could leave on your floor or other objects. The rust stains are usually difficult or impossible to remove. Also, be careful with your clothing. It would be a shame for your favorite trousers if they were soiled with unsightly stains.

Buy iron fertilizer

Iron fertilizers have a different composition depending on the product. As a rule, however, they always contain the nutrients nitrogen and iron, which are marked with the abbreviations N and Fe. We recommend that you only use iron fertilizer when absolutely necessary. Nutrient deficiencies can often be prevented. Our primarily organic Plantura Organic hydrangea fertilizer with long-term effect, for example, contains a small amount of iron to prevent iron deficiency in hydrangeas from the outset.

Make your own iron fertilizer

If you don't want to buy iron fertilizer, you have another option: producing it yourself. This protects your wallet and of course the environment. Because plants absorb iron as an essential nutrient element, it is naturally present in plant waste, bokashi or compost contain. Highly iron-rich plant material such as spinach, Chickpeas, lenses or kidney beans are particularly suitable for the production of iron-rich fertilizer. Because the bivalent iron, which is more readily available to plants, is only present in the compost at a low pH value priority, you can mix it with lemon juice or orange juice before using it as a fertilizer Mix.

An old trick works similarly, with which our body should be supplied with iron. Iron nails stuck in an apple oxidize as a result of contact with malic acid. Mixing the crushed apple slices with the potting soil also provides easily plant-available iron. But there's an even easier way: Many plants have such effective tactics of their own for extracting iron from the soil that just sticking iron nails into the potting soil can be enough. When planting - especially in the tub - mixing in plenty of yellow sand can also prevent iron deficiency. Because the yellowing of the sand comes from adhering iron oxides. Another very effective source of iron is blood meal, which can be purchased or slaughtered yourself.

If you have to struggle with moss in your lawn, you often use iron fertilizer. In our special article on the subject Iron fertilizer for lawns you will find everything you need to know about the application and alternatives.