A beautiful green lawn in the garden is a figurehead for every hobby gardener. Mineral fertilizers are quickly used to help out. But be careful, lawns can sometimes be damaged if they are over-fertilized.

In a nutshell

  • over-fertilization possible due to mineral fertilizers
  • typical signs of so-called "burns" in the lawn
  • Lawn plants can dry up without help
  • has been over-fertilized, thorough watering of the lawn will help
  • good alternative use of organic fertilizer

signs of overfeeding

When using mineral lawn fertilizer, it can sometimes quickly lead to over-fertilization. The motto: "A lot helps a lot!" is completely out of place here. The consequences can then be very serious for the lawn. Too many nutrients are not good for healthy growth, and serious damage will occur. The signs may be different depending on the degree of overfeeding:

  • excessive growth
  • brittle, soft, swollen culms
  • Dark green color when over-fertilized with nitrogen
  • initially yellowing of the tips of the stalks
  • later brown colouration
  • eventually discoloration of the entire plant
  • widespread death of grass plants

The discoloration of the plants is also known as "burning". The existing damage pattern in the lawn provides information about the degree of over-fertilization.

Notice: In the case of over-fertilization, the soil contains a relatively high concentration of fertilizer salts. This has a negative effect on the roots of the lawn grass. The plants become more susceptible to frost and also to fungal diseases.

formation of fires

Lawn burns are caused by exosmosis, essentially a reverse of osmosis. Normally, the concentration of minerals in plant cells is higher than in the soil. This makes it possible for the plants to absorb water from the soil accordingly, as this always migrates in the direction of the higher concentration of minerals. In other words, the roots literally attract the water. This process is known as osmosis. If the lawn is now over-fertilized, the following happens:

  • Increased mineral concentration in the soil
  • Water leaves the plant cells
  • flows back into the ground
  • no water absorption of the roots possible
  • Grasses turn yellow and dry up
  • superficial yellow-brown, bald patches visible

These spots appear burnt. The grass is corroded by over-fertilization.

Notice: If the lawn is over-fertilized, the high concentration of different nutrients allows lawn weeds such as sorrel and dandelion to take root unhindered if the nitrogen concentration is too high or if the iron content is too high. On the other hand, if there is an excess of lime, the grass will be pale yellowish. It suffers from chlorosis because iron cannot be absorbed.

Causes of over-fertilization

The reasons why a lawn is over-fertilized can be different. Over-fertilization usually occurs when a spreader is used to spread the fertilizer. Areas are often fertilized twice, so some of the plants receive an excessive concentration of nutrients. The typical yellow stripes then appear on the lawn. It is important:

  • pay attention to the lanes
  • to keep some distance between them
  • lanes not to overlap
  • Use a little less fertilizer
  • to lift the car in curves
  • to select an unspecified spreading level
  • better set one lower
  • Place fertilizer sacks on paved ground
  • also spreader when filling
  • Never exceed the recommended dosage on the packaging
  • prefer to use a little less
A spreader helps with even fertilization.

Another possibility is that fertilizer accidentally lands on the lawn while the wagon is being filled, or the bag simply tips over. An incorrect setting of the spreader can also over-fertilize the green. in these cases the fertilizer should be removed from the area as much as possible. Either by hand, but then don't forget gloves, or carefully rake off the turf with a rake.

Notice: The use of mineral fertilizers can lead to over-fertilization with nitrogen and phosphate in the long term. At the same time, the plants can be undersupplied with potassium.

Soil analysis provides information

Sometimes it can also be because the lawn is simply over-fertilized because the composition of the soil and the nutrients it contains are not known. When the first signs appear, even stopping fertilization is no longer of any use. The lawn plants can then suffer from an excess of certain nutrients, as well as from a lack of another. A further application of fertilizer would aggravate an already existing over-fertilization. therefore a soil analysis should be carried out. Proper action can only be taken when the exact nutrient concentration in the soil is known. In addition

  • Take samples from multiple locations
  • have them analyzed in the laboratory

In addition to the soil composition and the nutrient content, the soil analysis also gives a recommendation for further fertilization measures.

Tip: The lawn should be mulched regularly. The shredded lawn clippings are simply left on the surface. This contains important nutrients that are supplied to the soil.

Long-term measures in case of over-fertilization

After too much fertilizer, immediate help is needed to avert major damage to the lawn and still save it. Measures are:

  • copious, penetrating watering
  • put lawn sprinklers on for a few hours
  • Apply at least 15 liters of water per m² to the total area
  • mow brown and yellow areas to the ground
  • mow the entire area in the event of acute over-fertilization
  • Mowing depth 4 cm
  • Remove lawn clippings
  • then scarify
  • Soil becomes more permeable
  • then water as described
  • Improvement should occur after 14 days
  • otherwise application of new topsoil
  • Height 5 cm
  • then new sowing
  • roll or step down well
  • then water well
rolling the lawn

Tip: In the event of acute over-fertilization, mowing the entire area is recommended, as the plant matter contains a high concentration of nutrients. When they rot, they are released again and get into the ground.

frequently asked Questions

Why is extensive watering necessary after over-fertilization?

By irrigating the soil, the soil solution can be diluted in nutrients. The osmosis can be guided in the right direction again. The plants can absorb water unhindered again. This also causes excess nutrient salts to be flushed out. These are stored in deeper layers of soil, where they cannot damage the roots.

Can the lawn be over-fertilized with organic fertilizer?

No, it is not possible. Compost, horn shavings or semolina can be used, among other things. The nitrogen contained is organically bound and must first be broken down by microorganisms in the soil and converted into nitrate. Only then is it available to the plants and the osmotic effect can develop properly. These are so-called long-term fertilizers.

Are lawn plants always over-fertilized when they turn yellow and dry?

No, there does not always have to be over-fertilization. Sometimes grass plants turn yellow and dry in summer, especially on light, sandy soil and in the blazing sun. They then suffer from a lack of water. Sandy soils dry out very quickly and can hardly store any water. In the worst case, if there is no watering, the plants can dry up. An alternative would be to create a special dry grassland. This tolerates drought.

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Garden design