AlzChem Global
Agriculture

Calcium Cyanamide General/Effect

Up to what soil depth can calcium cyanamide hinder the growth of weeds?

The incompatible phase of calcium cyanamide acts only in the top 3 to 4 cm of the soil, affecting as a result most of the weeds that have germinated from seeds and even small weeds.
Weed seeds located at deeper levels, or weeds propagating by rhizoms, are not adequately sensitive.

 

Is it dangerous to use calcium cyanamide?
Is calcium cyanamide toxic?

The compound which is formed during the conversion of calcium cyanamide in the soil is cyanamide and not cyanide. Unlike cyanide, cyanamide forms no poisonous gases in the presence of moisture. Unintentional absorption of cyanamide can therefore take place only through the inhalation of dust or prolonged contamination through the skin. Cyanamide taken into the body is completely degraded in the body within 24 hours, and the degradation products excreted in the urine.  Therefore there is neither an accumulation in the body nor any long-term damage.  This has been shown through occupational medical examinations of workers at calcium cyanamide production facilities, some of whom have been in very close contact with the fertilizer on a daily basis for between 30 to 40 years.

 

Is the fact that calcium cyanamide has a high lime content desirable?
What effects does the application of calcium cyanamide have on the soil structure?

The calcium content of lime nitrogen is over 50% and is, moreover, extremely reactive.  Therefore in the soil calcium cyanamide is classed as a calcium multiplier.
Two-thirds of the calcium are directly bound to the nitrogen and thus immediately water soluble and available to plants.  One third of the lime consists of slow-acting forms of lime.
When applied to the soil surface it leads to topsoil-liming,  resulting in improved soil structure, less silting and incrustation, and improved soil respiration.
In addition, soil acidification is prevented.

 

Does cyanamide nitrogen also occur in nature?

Certain plants can form cyanamide, for example the hairy vetch and the Robinia-trees. So it is a naturally occurring compound.  Therefore the enzymes that are capable of degrading this compound again are also present in the soils.

 

Why does calcium cyanamide have a long-lasting nitrogen effect?

A special feature of calcium cyanamide is its delayed nitrate formation, which largely protects it from leaching losses.  This is because a small part of the cyanamide in the soil is initially converted into dicyandiamide (DCD).  DCD is a certified nitrification inhibitor and ensures that the nitrogen is only converted gradually over several weeks from the stable, non-displaceable ammonium form into nitrate. This is the reason for the recognized long-lasting and uniform nitrogen effect of calcium cyanamide.

 

Why should one avoid consuming alcohol after using calcium cyanamide?

The interaction of cyanamide with alcohol is well-known. Cyanamide taken into the body inhibits a particular enzyme in the body that is responsible for breaking down alcohol. As a result, acetaldehyde, a decomposition product of alcohol (!), accumulates temporarily in the blood, leading to dizziness, nausea and hot flashes. Because of this typical reaction liquid cyanamide is used in many countries as a drug to combat alcohol addiction. However, when calcium cyanamide is used in the garden properly it is unlikely that a sufficient amount of dust to trigger this unpleasant reaction would be inhaled.

 

What happens to calcium cyanamide in the soil?

Calcium cyanamide must first go through a series of transformation steps in the soil before it is finally available as ammonium nitrogen to the plants. As soon as calcium cyanamide comes into contact with soil moisture, the calcium cyanamide dissolves from the fertilizer grain and decomposes immediately into calcium hydroxide and cyanamide.  This process proceeds very rapidly even at low temperatures: with adequate moisture and good soil contact for the fertilizer granules - by working in the fertilizer to a shallow depth, for example – practically all of the nitrogen is available as cyanamide in the soil solution after just one day! This results in temporary concentrations in the top few centimeters of the soil which shallow-rooted plants and certain harmful organisms cannot tolerate. Therefore the calcium cyanamide fertilizer will also, to a certain extent, affect germinating weeds, soil-borne pathogenic fungi, slugs and wireworms. As new microbiological tests show, the soil microflora is only temporarily impaired in the process:  even at extremely high application rates the microbial populations exceed their initial levels after only few days. The biodiversity is then even greater than before fertilization. This is because the cyanamide promotes the development of some latent existing soil organisms since they are able to use it as a nitrogen source.

 

What are the differences between calcium cyanamide and calcium ammonium nitrate?

Calcium ammonium nitrate (CAN) contains 27% nitrogen in the form of ammonium nitrate. That means that half of the nitrogen (13.5% N) is already present as nitrate, the other half as ammonium, which is likewise fully converted in the soil into nitrate within 1-2 weeks.  CAN therefore acts rapidly and for only a relatively short period, so it promotes rapidly growing upper grasses in particular (surge growth). The high nitrate portion involves a certain risk of leaching and can also lead to elevated nitrate levels in pasture grass. The lime (calcium carbonate) content is so small that it cannot counter the acidifying effect of the nitrogen, so CAN has a slight acidifying effect on the soil.

By contrast, calcium cyanamide contains nitrogen (19.8%) almost exclusively in the form of a calcium cyanamide bond, and the nitrogen is chemically bonded to the lime. The nitrate content is only 1.8%.  The calcium cyanamide converts in the soil over various stages into ammonium nitrogen. But with calcium cyanamide the further conversion to nitrate is then greatly delayed because the fertilizer inhibits nitrate-forming bacteria in the soil. The ammonium is retained in the soil by the clay minerals and is not at risk of leaching. Calcium cyanamide therefore delivers an evenly sustained effect over many weeks. In particular this effect promotes the valuable lower grasses that provide for a dense sod/turf in the pasture. The lime content is over 50% and is, moreover, extremely reactive.  So calcium cyanamide is classed as a lime multiplier in the soil, while CAN on the other hand is a lime consumer. The highly effective lime in calcium cyanamide improves soil structure, prevents silting and allows rainwater to seep in more quickly.
Calcium cyanamide is the only fertilizer whereby the calcium cyanamide in the soil passes through the so-called cyanamide phase (max. 10 days), during which phase the calcium cyanamide in the soil works to counteract the eggs and larvae of pasture parasites. This hygiene effect ensures healthier horses. No other fertilizer can achieve this effect! At the same time the cyanamide phase also has a certain counteractive effect on freshly germinated weeds and rosette plants such as dandelions.

 

What distinguishes the effect of calcium cyanamide?

Calcium cyanamide contains nitrogen (19.8%) almost exclusively in the form of a calcium cyanamide bond.
The nitrogen is chemically bonded with the lime. The calcium cyanamide converts in the soil over various stages into ammonium nitrogen. But with calcium cyanamide the further conversion to nitrate is then greatly delayed because the fertilizer inhibits nitrate-forming bacteria in the soil. The ammonium is retained in the soil by the clay minerals and is not at risk of leaching. Calcium cyanamide therefore delivers an evenly sustained effect over many weeks. In particular this effect promotes the valuable lower grasses that provide for a dense sod/turf in the pasture. The lime content is over 50% and is, moreover, extremely reactive.  Therefore in the soil calcium cyanamide is classed as a calcium multiplier.
The highly effective lime in calcium cyanamide improves soil structure, prevents silting and allows rainwater to seep in more quickly.
Calcium cyanamide is the only fertilizer whereby the calcium cyanamide in the soil passes through the so-called cyanamide phase (max. 10 days), during which phase the calcium cyanamide in the soil works to counteract the eggs and larvae of pasture parasites. This hygiene effect ensures healthier pastures: No other fertilizer can achieve this effect! At the same time the cyanamide phase also has a certain counteractive effect on freshly germinated weeds and rosette plants such as dandelions.

 

Which forms of nitrogen are provided by fertilizers, and how do they differ in their effect?

The nitrogen fertilizers provided contain various forms of nitrogen in different combinations and proportions. What is important is the carbamide nitrogen as contained in urea, or the ammonium and the nitrate nitrogen as contained in calcium ammonium nitrate.

These forms of nitrogen have different effects. The plants absorb more than 90 % of the nitrogen in nitrate form. In general all forms of nitrogen are converted to ammonium and nitrate before they can be absorbed by the plants.

 
Urea nitrogen:

if nitrogen is not given as nitrate when used as a fertilizer but rather in the form of urea (= ureic nitrogen or amide nitrogen) it must first be converted to ammonium nitrate in order to be absorbed by the roots. During this process amide nitrogen is first converted from the enzyme urease, which is found in all types of soil, into ammonium. This process happens relatively speedily, and depending on the soil temperature takes between 1 to 4 days. The warmer the soil the quicker this reaction happens.

The ammonium that results is subsequently converted into NO2 by the bacterial strain Nitrosomonas, which in turn is converted into nitrate NO3 by the Nitrobacter strain.

Thus, during the conversion of amide nitrogen ammonium nitrogen is formed first and subsequently the nitrogen is converted to nitrate. In the first conversion stage, i.e. into ammonium, the pH value increases in the area where the fertilizer grain is. This is responsible for nitrogen losses that may occur in the form of gaseous ammonia released to the atmosphere. These losses can be kept manageable in extent through various measures, such as working in the fertilizer when tilling the soil, or spreading the fertilizer before precipitation.

 
Ammonium nitrogen:

Ammonium moves more heavily in the soil than nitrate.  Ammonium is distributed in the soil by diffusion processes. This is how it gets into the roots and can be absorbed by the plants.  A part of it binds to the clay and humus in the soil.  This is also why ammonium has a more restrained effect than nitrate nitrogen. Under natural conditions most of the ammonium is converted by soil bacteria into nitrate (nitrification), and in doing so becomes effective.

Therefore it is mistaken to aim for a strongly ammonium-based nutrition of plants by applying a fertilizer that has a high ammonium content.

One exception is fertilizers with stabilized ammonium nitrogen (ENTEC, Alzon) and calcium cyanamide. With these fertilizers the ammonium conversion is delayed. Ammonium is retained in the soil for longer in this way. This enables the plant to take in greater proportions of ammonium.

 
Nitrate nitrogen:

Nitrate moves freely in the soil. It is dissolved in the soil water and through the soil water accesses the roots, where it is taken up into the plant.  This is why nitrate works so quickly. However, it can also be relatively quickly leached out of the root horizon of the soil.
 

Nitrogen fertilizer with beneficial side effects:

Calcium cyanamide has one particular feature that distinguishes it from other nitrogen fertilizers. It has to first pass through the conversion stages in the soil described above before it is finally available as ammonium nitrogen and nitrate for the plants.  As soon as calcium cyanamide comes into contact with soil moisture, the calcium cyanamide dissolves from the fertilizer grain and decomposes immediately into calcium hydroxide and cyanamide.  This process proceeds very rapidly even at low temperatures – with adequate moisture and good soil contact for the fertilizer granules - by working in the fertilizer to a shallow depth, for example – practically all of the nitrogen is available as cyanamide in the soil solution after just one day! This results in temporary concentrations in the top few centimeters of the soil which shallow-rooted plants and certain harmful organisms cannot tolerate. Therefore the calcium cyanamide fertilizer will also, to a certain extent, affect germinating weeds, soil-borne pathogenic fungi, slugs and wireworms.

 

How long does the cyanamide nitrogen remain in the soil?
Why can remains of the fertilizer granules be seen on the soil surface even a long time after spreading?

Within only 5 to 7 days after calcium cyanamide has been spread the cyanamide will have converted fully into urea and other non-toxic nitrogen compounds. Remains of the fertilizer granules which you can still see lying on the soil are the lime and carbon portion of the fertilizer.

 

Is calcium cyanamide harmful to soil life?

As new microbiological studies show, the soil microflora is only temporarily impaired by using  calcium cyanamide:  even at extremely high application rates the microbial populations exceed their initial levels after only few days. The biodiversity is then even greater than before fertilization. This is because the cyanamide promotes the development of some latent existing soil organisms because they are able to use it as a nitrogen source.