5 dangerous fertilizer myths we believe in

And what if the well-established rule “phosphorus is for root formation, nitrogen is for shoot growth” is nothing more than a harmful myth? An American expert debunked 5 popular beliefs about plant nutrition.

Sensational statements of the associate professor Selkhoznuk from Washington State University shaken the foundations of the theory of mineral fertilizers.

American Linda Choker-Stonebased on numerous studies and his many years of experience, he resolutely refuted many common rules for applying supplements.

Associate Professor of Agricultural Sciences at Washington State University Linda Choker-Scott

Myth number 1: Phosphorus - for root formation, nitrogen - for the growth of shoots


The theory that phosphorus-containing fertilizers stimulate the development of the root system, and nitrogen-containing ones - the formation of shoots, has long been perceived as an axiom that does not require proof. According to Linda Choker-Scott, this popular belief arose through the active use of phosphate fertilizers in industrial agriculture before planting annual crops.


Phosphorus is truly one of the main inorganic macronutrients essential for plants. The fact is that it is quickly washed out of the soil, which is used on a large scale for agricultural use. To "return" depleted reserves to the soil, fertilizers with phosphorus in the composition are applied for planting.

In urban landscape parks, the situation is completely different. In this case, we are talking more about stressful conditions in which trees and shrubs have to grow: polluted air, lack of watering in summer, poor shelter for the winter, defeat by pests, lengthened daylight due to urban lighting. Add to this an excess amount of phosphorus and as a result, you will not get accelerated plant growth, but redness of their leaves.

In addition, in the planting of perennials on small private land holdings, phosphorus deficiency is also quite rare. Most often, agronomist says, the soil is poor in nitrogen.

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That is why the introduction of ammonium nitrate leads to a "boom" of shoot growth - it merely restores the balance of elements in the soil. Naturally, with a deficiency of any of the important components, the growth of plants slows down, and with the completion of its deficiency, it continues. There is nothing supernatural about it.

At the same time, additional fertilizing with phosphorus, unlike nitrogen fertilizers, does not provoke the appearance of shoots. The logic of gardeners was simple: if the “tops” do not grow, therefore, the “roots” should grow. According to the American scientist, this misconception is very dangerous.

What is dangerous myth?

If excess nitrogen is not "deadly", then an excess of phosphorus is fraught with leaf lesions with glandular chlorosis. The fact is that excessive levels of phosphorus in the soil makes it difficult for plants to assimilate manganese and iron. In turn, manganese and glandular "starvation" and lead to the appearance of spots on the leaves.

In addition, a surplus of phosphorus can disrupt mycorrhiza - a symbiosis of fungi and plant roots, due to which the latter better absorb water and nutrients from the soil.


This is what Associate Professor Choker-Scott advises:

  • Do not use phosphate fertilizers when planting seedlings. In most cases, it is preferable to make a nitrogen supplement.
  • If nitrogen fertilizer does not solve the problem of lack of nutrients, and you suspect that the plant needs another element, do not rush to feed into the ground - first spray the plant itself. If the symptoms of fasting on the leaves are gone - you can safely make the necessary dose in the traditional way. Trial foliar feeding helps to avoid imbalance of elements in the soil.
  • Use natural mulch (bark of coniferous trees, fallen leaves, etc.). This "coat" will slow the release of phosphorus and other important macro - and micronutrients. As you know, prolonged-release fertilizers are much more efficient than fast-acting ones.

Myth number 2: For good growth and flowering roses need phosphorus


Many growers are advised to make a stunning amount of "chemistry" for planting roses: superphosphate, phosphorite, and triple superphosphate. Sometimes it is also advised to “flavor” the soil with bone meal and manure. The American expert decided to figure out how justified the use of such a "explosive mixture."


The American admits that she has carefully studied studies on the effect of phosphorus on the flowering and root formation of roses and has not found any weighty arguments in defense of phosphorus dressings when planting seedlings of this crop.

What is dangerous myth?

Numerous scientific works and experiments have proved the presence of a symbiosis of roses and beneficial fungi. Introducing phosphate fertilizer, you prevent the fungus from "colonizing" the root system of roses. As a result, it is much more difficult for plants to extract water and nutrients from the soil.

In addition, the "contamination" of the soil with minerals kills beneficial microorganisms and reduces the biological activity in the soil.

As a result, roses grow worse, they get sick more often, which forces inexperienced roses to conduct additional fertilizing.


Do not apply phosphate fertilizers when planting rose seedlings. The soil at the dacha is extremely rarely deficient in this element. It is preferable to feed the roses with complex fertilizers and organic matter.

Myth number 3: Bonemeal is useful to make in the landing pits


Of all types of fertilizers, dung is the most popular among truckers than bone meal, except manure. Proponents of natural farming praise the product of bone processing for its organic origin. Without exception, adherents of using this fertilizer are convinced that it reduces stress in seedlings during transplantation, stimulates root formation, and saturates the soil with calcium and phosphorus.


Bonemeal is really for the most part consists of two elements: calcium and phosphorus. Both are essential for plant growth and development, but in high concentrations both are dangerous. As mentioned above, this is especially true of phosphorus.

So why do a lot of experts continue to argue that phosphorus-containing supplements are necessary to stimulate rooting? Let's go back to mycorrhiza. With healthy symbiosis, the fungi that live on the root system of trees and shrubs, release phosphorus from the soil. However, in the case of an overdose, symbiotic relationships simply do not arise.

As a result, the plant has to compensate for the absence of a “helper” in the form of a fungus and throw all its forces on the formation of roots.

What is dangerous myth?

As a result, phosphate fertilizer still gives an impetus to the process of rooting, but at what cost! The above-ground part of the plant is weakened, and the roots hardly get food from the soil.

It turns out that bone meal only creates the appearance of good growth and survival of seedlings, but in fact only "complicates" the plants life.

Interestingly, bone meal is toxic to all members of the exotic Protean family.


  • Do not add bone meal to planting pits..

  • If you have doubts that your soil is still critically lacking phosphorus, we recommend to start test for soil compositionso as not to "overfeed" her. If the excess of the concentration of this insidious element is confirmed, you can go two ways: slow (stop the application of phosphorus-containing fertilizers and wait for the soil composition to return to normal) either fast (add ammonium sulphate, magnesium sulphate, ferrous sulphate or zinc sulphate to restore balance).

Myth number 4: foliar top dressing more effective root


Quite often you can hear the odes that gardeners sing foliar dressing. Especially like to advertise this method of fertilizer manufacturers of liquid complexes. Proponents of spraying plants with essential nutrients state that the aboveground part of the plant absorbs them much faster.

On the packaging of some liquid fertilizers, you can read bold assertions that substances introduced by foliar feeding are absorbed in 8, 10, or even 20 times better than with traditional watering at the root. Believe it or not?


Linda Choker-Scott cites a study by the University of Michigan conducted in the 1950s by Dr. Tukey. With the help of an isotopic substance, the scientist was able to prove that a leaf of a plant is able to effectively absorb nutrients. Yes, not in such large volumes as the roots, but still very effective.

Does this mean that all agronomists have a reason to switch exclusively to foliar feeding? Of course not! The fact is that the ability to absorb nutrients and moisture through the sheet plate is individual and differs in different types of plants. Most often, this method is effective for mass commercial cultivation of fruit crops.

Again, foliar dressings are good as a test of the state of the plant. If on the external signs you came to the conclusion that the plant lacks, for example, calcium, first try spraying the leaves with it. If the symptoms of deficiency of elements have passed or decreased, then the assumption was true, and it is possible to introduce a deficient element into the soil without fear of causing an imbalance in its composition.

What is dangerous myth?

The first possible negative effect of this agricultural technology is obvious: fanatically sprinkling a culture that poorly perceives foliar dressing, you risk to starve it with “hunger”.

The second risk is the wrong choice of fertilizer concentration. The slightest mistake - and you can simply burn the plant, especially when it comes to fertilizing with minerals.

The third nuance is that the fertilizer will be successfully absorbed by the leaves, but the nutrients will not reach all parts of the plant. This means that foliar feeding will not solve the problem of deficiency of nutrients in the root system.


  • Before carrying out dressings carefully study plant susceptibility information on your site to foliar application.

  • Do not rely on spraying fertilizer as a reliable way to provide plants with all the necessary nutrients. Use foliar feedings as a test for deficiency of elements.
  • Preferable spray plants with micronutrients. They are absorbed through the leaves better than macronutrients.
  • Spray plants in the morning and if possible on cloudy, cloudy days. This will reduce the risk of burns on the plate.

Myth number 5: Fertilizer injections - the most effective way to feed


This is not to say that this "belief" is widespread in our area, but many Western gardeners and gardeners sincerely believe that local fertilization with shots into the stem or soil is the most effective, progressive way to feed the plants.

Herbal injections, according to manufacturers, are actually capable of working wonders. First of all, this method is used to treat glandular chlorosis (yellowing of leaves). The composition of injections may be different - this is both complex fertilizers, and individual elements (iron, calcium, nitrogen, etc.).


The "magic" injection will really give an instant result - new shoots will start to grow, the leaves will restore a healthy coloring. But the quick effect is never sustainable. Local fertilization is as effective as a citramonum pill for cervical osteochondrosis: it will temporarily relieve headache, but it will not solve the problem.

But what about the injections in pristvolny circles? Scientists have shown that the effectiveness of this method of fertilizer application is the same as with traditional root dressing. Is it worth paying more for fashionable phytoinjections?

What is dangerous myth?

In fact, according to Associate Professor Choker-Scott, some studies have found that trees that received nutrient injections into the trunk are more susceptible to pests.

In addition, often injections of nutrients to plants are simply not needed. For example, the leaves may turn yellow not only from iron deficiency, but also from changing weather conditions, virus damage or an invasion of pests. Imagine what would happen if, after each sneeze in the clinic, you would be given another injection.


  • Carefully investigate the causes of yellowing or wilting of leaves on trees and shrubs. Do not rush to label "nutritional deficiencies".
  • Do not feed fertilizer directly into a tree trunk. This is an aggressive intervention that can lead to disease and death of the plant.
  • Mulch tree trunks on peat soils, to reduce the risk of rapid leaching of mineral elements from the soil.

Perhaps the findings of the American scientist will make you think about how and in what doses you are applying top dressing in your backyard. Have something to say? We are waiting for your opinion in the comments to this article or on our forum!

Based on wsu.edu

Watch the video: Organic Food: Healthy Or Great Myth? (February 2020).