Iron fertilizer: application & effects of iron sulfate

Iron as a nutrient is mainly needed for the formation of enzymes. Learn how iron fertilizer is used and whether it is toxic.

Not only we 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 recognize in our plants whether they are deficient in iron and whether we need to help with some fertilizer? We provide the answer to this question as well as further information on the subject of iron fertilization.

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

Overview of the properties of iron

Iron is an important part of our life. It is used as a building material in our houses and even our breakfast juice is fortified with iron. We can also find iron in the periodic table, under the element symbol Fe, from the Latin name ferrum derived. Iron is a heavy metal that can be found either as bivalent or trivalent iron (Fe²⁺ or Fe³⁺) or in compounds (oxides, salts). For our plants there is only Fe²⁺ interesting, because they can take in and feed on it. The Fe³⁺ is not directly available to the plants. The bound iron can be released from the various minerals through weathering. During this weathering, iron ions are released, but several factors influence the availability of iron, such as the pH value and the humidity. In a moist soil with a pH value of 6 to 6.5 there is usually a large amount of Fe²⁺. If the pH value rises above 6.5 and you also have to struggle 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?

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

Iron has another important role 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 nutrients absorbed - an extremely important process for all living beings. Iron is often a component of various enzymes that play different roles in the metabolism. The Fe³⁺ is not directly available for the plants, because it has to be in the soil in Fe²⁺ converted or chelated. Plants can only use Fe²⁺ or chelated Fe³⁺ take up. Chelates are complexes that can be absorbed 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 well 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, and 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 that leaves turn yellow, while the leaf veins remain green - this is what is known as chlorosis. These chloroses form first on the young leaves. As the deficiency worsens, necrosis (dying tissue) forms from the edge of the leaf. When iron deficiency occurs, there is also a deficiency in chlorophyll, protein and energy. Therefore the growth and the yield of the plant decrease. The color of flowers can also fade and these can remain smaller overall. In the case of iron deficiency, the roots are usually short and have many short lateral roots. If the iron deficiency is not treated, your plants can even die - but only if the deficiency is severe.

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

Summary of signs of iron deficiency in plants:

• The presence of chlorosis, with the leaf veins remaining green
• Signs first appear on the young leaves
• Later, necroses appear starting from the leaf margin
• Inhibited growth
• Low yield
• Pale, small flowers
• Occurrence of short roots and many side roots

Drought and compaction can also prevent the plant from absorbing iron. It is therefore worth watering the plants properly after a long drought. Waterlogged and compacted soils 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 mainly organic fertilizers like ours Plantura organic fertilizers can put an end to compaction.

Another important factor that triggers iron deficiency is the excess of others Heavy metals in the soil. The transport and absorption of iron can be inhibited if many ions of chromium, copper, cobalt, zinc, manganese or nickel cavort 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 equilibrium of the ions in the soil is disturbed. The interplay between iron and phosphorus is particularly interesting. If there is a lot of phosphorus in the soil, it is possible that these two nutrients combine to form ferric phosphate. We know this compound as slug pellets, but it can also form in the soil and thus bind nutrients.

Here we have again briefly listed the iron deficiency triggers for you:

• 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. Since iron can be absorbed through the roots and through the leaves, there are several possible uses for this.

Iron foliar fertilization

Iron can not only be fertilized through the soil, but also as foliar fertilization. The advantages of foliar fertilization are that the effects are very quick. Since the fertilizer is not introduced into the soil, it cannot be washed out and is effective despite the dry soil. However, foliar fertilization can only be applied at a low concentration in order to avoid damage to the leaves.

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

Iron fertilizer in the irrigation water

You can also add iron with the irrigation water. To do this, you dissolve the iron fertilizer in the irrigation water according to the product description and give 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 the last of the product residues. Also, be careful not to stain the floor or your clothes with the iron manure. This results in unsightly rust stains that are either difficult or impossible to remove.

Which plants are often affected by iron deficiency?

Put simply, crops that are particularly draining are often affected. Ornamental plants like Roses (pink), Hydrangeas (Hydrangea), Magnolias (Magnolia) and Rhododendrons suffer particularly often from it. Rhododendron and rose fertilizers often already contain a small amount of iron to prevent chlorosis due to iron deficiency. Also heavy consumers of vegetables such as tomatoes (Solanum lycopersicum), Cucumber (Cucumis sativus) and paprika (Capsicum) struggle with iron deficiency.

In the case of fruit, one often finds one in the case of berries, Apples (Malus) and quinces (Cydonia oblonga). The flower lovers among you who love 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 an iron deficiency. More about a Chlorosis in petunias you can also find out here.

Iron fertilizer for lawns and against moss

Your favorite green lawn can also suffer from iron deficiency. This is mostly caused by the nature of the soil. Some soil contains more iron, while others contain less. But to be absolutely sure, you can do a soil survey. One way of using iron fertilizer on the lawn is to control unpleasant moss. If your lawn is heavily mossed, you can treat the damp moss with iron fertilizer. Before doing this, you should mow the lawn to a length of about 3 to 4 cm and then treat the moss with the iron fertilizer (iron (II) sulfate). Iron fertilizers 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 the months of March or April, if the soil is already completely thawed. After that, the moss dies after about two weeks and turns brownish to black. You can then simply remove the moss with a rake or rake. It is especially important that you fill in the gaps that the moss leaves behind.

After the removal, you should come back Sow grassso that no other weeds or moss colonize. If you do this moss removal in the spring, it is ideal so that the overseeding can grow well. Do not step on the lawn for approximately two weeks after applying iron fertilizers. Also, keep your pets away from the lawns - there could be symptoms of poisoning. What else are you against Moss in the lawn can be found here in our special article.

We recommend always supplying your lawn with sufficient nutrients and using primarily organic long-term fertilizers like ours Plantura organic lawn fertilizer to put. This will not only make your lawn fit and lush green, it will also protect the life of the soil and you will always be able to step back on your lawn immediately after fertilization. More information about our Organic lawn fertilizer You will find here.

Iron fertilizer for aquariums

Aquarium plants also need nutrients, because if the plants show chlorosis, they too lack iron. The fact that iron deficiency is not so rare in the aquarium is shown by the fact that the first aquarium fertilizer on the market was an iron fertilizer. A general recommendation for the amount cannot be given. Each aquarium is individual with regard to the filling quantity, the filter systems, the stocking, the feeding and the 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 adequate iron content is the growth of duckweed. If you have duckweed in the aquarium and enough iron, the lentils will reproduce well. If there is a lack of iron, the duckweed stop growing. Unfortunately, fertilization in the aquarium - regardless of the nutrient involved - is often associated with the formation of algae. Therefore, you should be very careful with the dosage and fertilize a little less than too much.

Is iron fertilizer poisonous?

In general, iron fertilizers are poisonous and you should always avoid body contact with these fertilizers. Wash your hands thoroughly if they come in contact with them. If you have any complaints after contact with iron fertilizer, you should definitely consult a doctor.

But not only the toxicity should 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. Be careful with your clothes as well. It would be a shame about 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 identified by the abbreviations N and Fe. We recommend that you only use iron fertilizers when absolutely necessary. Often nutrient deficiencies can be prevented. Our mainly organic Plantura Organic hydrangea fertilizer with long-term effect contains, for example, a small amount of iron to prevent an iron deficiency in hydrangeas from the outset.

Make iron fertilizer yourself

If you don't want to buy iron fertilizer, you have another option: that of your own production. This protects your wallet and of course the environment. Because plants absorb iron as an essential nutrient element, it is naturally found in vegetable waste, Bokashi or compost contain. Highly ferrous plant material such as spinach, Chickpeas, lenses or kidney beans are particularly suitable for producing iron-containing fertilizers. Because the divalent iron, which is more readily available to plants, is only found in compost when the pH value is low priority is given, you can use this as a fertilizer with lemon juice or orange juice Mix.

An old trick that was supposed to be used to supply iron to our body works in a similar way. Iron nails inserted into an apple oxidize as a result of contact with malic acid. Mixing the apple wedges with the potting soil also provides iron that is easily available for plants. But there is an even simpler way: Many plants have such effective tactics for extracting iron from the ground themselves that just sticking iron nails into the potting soil can be enough. Mixing in plenty of yellow sand when planting - especially in the bucket - can also prevent iron deficiency. Because the yellow coloration of the sand comes from adhering iron oxides. Another very effective iron supplier is blood meal, which can be bought or obtained from your own slaughter.

Those who struggle with moss in the lawn often fall back on iron fertilizers. In our special article on the topic Iron fertilizer for lawns you will find everything you need to know about the application and alternatives.