Iron fertilizer for lawns: application & alternatives

Iron fertilizer is said to help reduce moss in the lawn. Read here when you can save the money on iron fertilizer and how a shortage arises.

That seems to be the case in the spring Moss in the lawn often to have increased again. In search of solutions to this problem, sooner or later every lawn owner hears about the possibility of getting rid of moss with iron fertilizer. We create clarity in the confused moss carpet of dangerous half-knowledge, well-intentioned advice and real specialist knowledge.

Iron is an essential nutrient element for all plants. In the following we would like to explain to you why a lawn needs iron, whether iron fertilizer combats moss in the lawn and how you can recognize an iron deficiency. Then we go into how iron deficiency can arise and when fertilization with iron is necessary - there are usually far better alternatives.

General information about Lawn fertilizer can be found in our special article.

Why does the lawn need iron?

Lawn grasses need - like any other plant - the 14 essential nutrient elements in order to be able to live and reproduce. In addition to the main nutrients nitrogen (N), phosphorus (P) and potassium (K), magnesium (Mg) is also absorbed in larger quantities by the lawn. Iron (Fe) is one of the trace elements. These are only consumed in very small amounts, but are no less important than the main nutritional elements for that reason. Iron, for example, plays a key role in controlling enzyme activity in plants and thus also enables proteins and green chlorophyll to be built up. The plant also needs it to regulate cellular respiration, during which energy is obtained from carbohydrates.

Tip: Many lawn fertilizers contain the trace element iron and advertise its content. In fact, iron is the most abundant nutrient element in soil. That deficiency occurs because the lawn has drawn all of the iron present from the soil extremely unlikely: after all, iron only makes up about 0.01% of the dry plant mass on average the end.

Iron fertilizer against moss in the lawn

In not a few people's minds, as well as in Internet forums, there is a rumor that moss in the lawn can be combated with iron fertilizer. In fact, with the application of iron sulphate (FeS0₄) achieve a certain effect: the reaction of FeSO₄ in aqueous solution is acidic. Spreading the soil can cause a very rapid pH change in the soil, which the moss plants do not tolerate well. As a result, these die off and can be raked out. However, this effect is short-lived. The acidification of the soil under the lawn makes it even easier for the moss the next time you try it. And the constant alternation of iron sulphate and lime is not a solution either: one Accumulation of calcium, iron and sulfur in the soil will sooner or later lead to excess symptoms at the lawn.

A long-term solution to displacing moss is just a change in the favorable factors: waterlogging, soil compaction, shade, lack of or incorrect fertilization and the choice of one Unsuitable lawn seed mixes cannot be remedied by spreading large amounts of iron fertilizer - even if some of the vendors of the generous 10 liter buckets would like to believe you permit.

Detect iron deficiency in lawns

An iron deficiency manifests itself as chlorosis (yellowing) of the stalks. What is special about iron deficiency is that the leaf veins stay green longer than the area in between. In addition, the symptom always occurs on the youngest stalks first - unlike in the case of nitrogen deficiency, which affects the older stalks first. In order to distinguish between an iron and a nitrogen deficiency, you have to look very carefully. In the case of a severe deficiency, a whitish discoloration can even occur.

Reasons for iron deficiency in lawns

The most common reason for iron deficiency is not the absence of iron. If there is no lack of iron, normal iron fertilization has no significant effect on the nutritional status of the lawn.

Iron exists as a trivalent and a bivalent iron ion in the soil. Plants usually only take iron as a divalent ion (Fe²⁺) on. The two ion forms are in a chemical equilibrium with each other, which can shift: If the soil is more acidic, there is a lot of Fe²⁺ and there is no deficiency in any case.

On the other hand, if the pH value is high, there is more Fe³⁺ that normally cannot be recorded. Relative iron deficiency can occur. However, grasses have a strategy that is unique in the plant kingdom: They form mugeic acids, which have a very strong attraction on Fe³⁺ to have. These mugeic acids are transported out of the roots and into the root space, where they contain Fe³⁺ tie. At the same time, special transport channels are built up in the outer cells of the root, which are specialized to absorb the iron ions including mugeic acid. Grasses are therefore able to absorb iron when the pH value is actually too high. However, because this physiological adaptation costs a lot of energy, it is only possible if the plant can operate an active metabolism for energy production. For this reason, anything that inhibits the life processes of the lawn can lead to a relative iron deficiency if the pH value of the soil is too high. In the following table we have summarized for you what causes a relative iron deficiency in lawns and what you can do about it.

Which leads to relative iron deficiency	solution
Waterlogged or compacted soil	- Regular scarifying, aeration, sanding (no more than once a year) - On no account fertilize sulfur, because this binds Fe2 + so that it is not available - Long-term: fertilize organically to keep the soil loose and well ventilated through humus formation
Dry soil that does not hold water well	- Long-term: fertilize organically to improve water storage capacity through humus formation
Calcareous soils with a high pH value	- Use of acidic fertilizers (e.g. B. Ammonium sulfate), only water with rainwater, regular distribution of acidic materials - e.g. B. Compost made from rhododendron leaves, coffee grounds, softwood and ammonium

As a rule, therefore, only a relative iron deficiency occurs in lawns. However, there can also be an absolute deficiency at special locations where no iron can be formed from the parent rock through weathering. Raised bog soils and peat substrates do not contain any iron reserves. In the rare event that your lawn grows on such a substrate, iron fertilization may be appropriate.

Tip: Generally difficult living conditions can therefore cause a relative iron deficiency in lawn grasses, even though iron is present in the soil. You can prevent an overburdened lawn by using a lawn seed mix that is right for your location right from the start. Here we have put together for you, which lawn type makes sense when is!

Iron fertilizer for lawns: application and application

Iron fertilization with iron (II) sulfate can be carried out on healthy soil with a normal pH value. Sulfur and iron ions dissolve in water and can be absorbed by the plants. However, if there is a lack of oxygen due to waterlogging or soil compaction, they tend to come together again and are then difficult to dissolve. Fetrilon® is a complex fertilizer with many micronutrients. It contains several trace elements in a special, soluble compound. Radigen® is also a fertilizer with several trace elements, which has a gentle long-term effect. In the case of severe and acute deficiency, iron (II) sulfate, iron chelates or iron citrate can be applied as foliar fertilization.

Please note: Because of its acidic reaction with water, iron (II) sulfate has a corrosive effect on the skin and mucous membranes. Animals as well as humans can suffer severe damage if they are touched or even swallowed. A lawn treated with iron (II) sulphate should not be stepped on for at least 24 hours and should also be as inaccessible as possible to wild animals and domestic animals. In addition, granules worn on the pavement on shoes or paws lead to rust stains on many materials. These stains can only be removed again with even stronger acid.

Iron fertilizer for lawns: benefits & alternatives

In summary, it can be said that in most cases iron fertilization is not necessary and has no effect. A general improvement of the soil, on the other hand, reliably helps to prevent an iron deficiency. With organic lawn fertilization, for example, this is still possible without any problems long after the lawn has been planted. Our Plantura organic lawn fertilizer and our Plantura organic autumn lawn fertilizer are certified organic and have everything to keep your soil and lawn healthy and iron available.

This special article provides general information on organic lawn fertilizers. This article also tells you about Organic lawn fertilizer.