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JJ the Gardener

Plant Nutrition - Nitrogen

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Plant Nutrition



Nitrogen, a basic and standard plant food.  However the idea of a "food" can be problematic for some gardeners when it comes to managing as we humanize the subject of supplying the plants with nutrition.  I will discuss plant nutrition more like building materials for a construction job. 

As a gardener it is your job to supply the materials as needed.  If you send to much or to less it causes problems from uptake to use to storage.  If you care what you will get from your garden.  Be competent, diligent and not impulsive.


Carbon and Nitrogen

Carbon is obtained by plants mostly by C02 and thus is how in part plants can grow hydroponically and in soils of various stages.  Nitrogen type, growth speed vs transpiration rates will effect the internal carbon of the plant.  A balance of nitrogen to internal carbon with yield is the ideal goal.

In plants this carbon is often stored in the pith sections.

As a plant develops it uses and stores more nitrogen during the vegetative period and will relocate nitrogen from lower leaves later in bloom when needed.  Increasing nitrogen in bloom to account for nitrogen deficiency can extend the bloom to harvest period and offer a sub par harvest.



Early Growth Considerations

Before we begin to consider applying fertilizers we need to consider a few things but essentially we want to consider plant transpiration and nitrogen volatization and mineralization in the soil and media.

  • Environment with considerations to
    • Temperature & humidity in terms of vapor pressure density for your crop area.
    • Dry and Wet conditions.
  • Root structure of plants
    • Feeding plants that have proper roots will ensure the plants can store enough nitrogen for the blooming stages.  Most of the nitrogen for the plants needs will be taken up and stored in the roots in the vegetative stage and reaching correct to optimum levels is important of yield goals.
    • The plants will make many chemical reactions and create many substances that all pretty much have other important uses in the plant.  Having early deficiencies with nitrogen can cause problems later in the grow on a variety of fronts.
    • Root structure and metabolism can lead to differential accumulation of nitrogen.
      • This happens when environmental or other reasons growth is slowed due to transpiration and assimilation issues.
      • Also can occur from uneven watering of the soil media.
      • This is a negative as it concentrates nitrogen in areas you do not want it and can extend a harvest.
      • Input of nitrogen in bloom stage can create new growth if concentrations are too high. 
      • Generally keep Phosphorous and nitrogen in the correct ratio for the applicable plant stage.


Types of Nitrogen

  • Nitrate Nitrogen
    • Must be converted prior to use internally in the plant.
    • Nitrogen can be leached easily from soils and medias.
      • More humid climates tend to have poorer nitrogen soils due to leaching.
    • + charge (type of nitrate can fluctuate in + value)
      • This can effect PH of the media.
        • The plant will release a - ion for a + Ion.
        • This build up in the media can alter the PH of the media depending on a variety of factors.
    • Molybdenum is needed to convert nitrate to ammonia to be use in the plant.
    • Nitrogen metabolism takes place in roots and the leafs (shoots).
      • Respiration and transpiration rates affect the plants ability .
        • Environment, EC, plant stage and media conditions are all factors.
    • The assimilation of nitrate is an energy-consuming process,
      • using the equivalent of 15 mol of adenosine triphosphate (ATP - is energy from photosynthesis) for each mole of nitrate reduced (16).
    • Storing nitrate is not toxic.
    • Nitrate can be made mobile.


  • Ammonia Nitrogen
    • Ammonia nitrogen can be used by the plant immediately when foliar fed.
    • Ammonia nitrogen can be assimilated twice as fast as nitrate.
    • Ammonia is broken within 3 days to a few weeks depending on temperature and PH of media by biolife and turned into nitrite.
      • Ammonia in high concentration can stop the nitrogen cycle.
      • Nitrogen cycle
      • Water logged media can remove the soil bacteria and ammonium increases becomes toxic to your plant.
    • Ammonia has a negative - charge.
      • This can effect PH of the media.
        • The plant will release a - ion for a + Ion.
        • This build up in the media can alter the PH of the media depending on a variety of factors.
    • Ammonia nitrogen has a high energy requirement.
      • The assimilation of ammonia requires an additional five ATP per mole.
      • In roots, as much as 23% of the respiratory energy may be used in nitrate assimilation compared with 14% for ammonium assimilation (17).
    • Ammonium is toxic at even low concentrations and must be metabolized into organic combination. Consequently, ammonium metabolism for detoxification may deplete carbon reserves of plants much more than nitrate accumulation.
      • Glutamine synthetase an enzyme created via several processes nitrate reduction but is necessary for ammonia absorption.
        • Part of domino effect of problems if deficiencies shut down.
        • An in part reason why a nutrient is typically made up of a nitrate and ammonia %.
        • The plant will go into phytotoxic conditions if Glutamine Synthetase is reduced or prevented.
  • Their are several parts of ammonia with in the plant assimulation process but each process makes an enzyme or amino acid that is used in another process.


Nitrogen Aspects

Their are many enzymes, amino acids, and other types of chemicals made during the internal processing of the different states of internal nitrogen use.  Some of these products and/or their % may indicate stress factors or assist in other functions of the internal plant processes in terms of making the process function in some detoxification way.  Detecting these signals can assist in future planning.

  • It is important to understand that concept as I will tie that in later in advanced growing writing when talk about making changes via stress by altering hormone and auxin levels.
  • This is important in Plant Tissue Testing. (Not THC or CBD but for analysis of growth and deficiency)

Nitrogen and other NPK % can affect internal plant signals and alter its growth condition based on those signals.

  • Higher Phosphorous than nitrogen signals flowering aspects in some plants.
  • Longer flowering tropical plants will use nitrogen over a longer period of time but you generally fertilize similar for each period of growth.  Generally only the length of the development periods is different.
  • Ammonia and Nitrate nitrogen % of a recipe can be used to help regulate PH in regards to some medias.


Optimal Nitrogen Use

When we think of optimal we think we can open up a book or jump on the device known as the internet and find our answer.  Their is no true answer that you seek like that.  You can find ranges but the answer you seek is unique and complicated to be that simple.

  • Optimal comes from environment, overall nutrition, plant management, competence and diligence.

Nitrogen is very difficult to determine for yield as the plants are not visibly showing when they are at their "sufficiency" or optimum for yield and is known as critical concentration.  Continued use of nitrogen will accumulate to toxicity. 

  • The gap from sufficiency to toxicity can vary from large to small.
  • With a nutrient supply in which all elements except nitrogen are held at a constant high level,
    • The concentration of nitrogen within the plant should increase with growth and yields, with increases in nitrogen supply.
  • Nitrogen concentrations in leaves are often not correlated with increased growth and yields.
    • Green color of leaves does not indicate optimum or even wholly problematic levels.
      • Changes and timing of nitrogen levels can affect harvest time periods.
    • Nitrogen concentrations will diminish in leaves, stems, and roots as the plants mature but added nitrogen will go to the plant tissues and become concentrated.
    • Levels vary by the time of day in regards to the daily life function of the plant.
      • In morning or when light starts about 2 hours after.




The only way to truly determine absolute nitrogen optimum for your plants is via plant tissue testing.  For small farms this may not be large factor but for medium and large farm operations this difference can be a noticeable saving when adjusted for yield and cost efficiency.

  • With this information precise nutritional formulas can be developed for specific locations with respects to its specific environment and plants.
  • Tested plant material should be collected at same light conditions and time of day and location of plants.
    • leaf from same exact location on several plants per section for example.

The use of information on internal concentrations of nitrogen in plants should not be directed toward forecasting of yields as much as it should be used in assessing how yields can be improved by fertilization in reference to other nutritional issues.  In part this is due to still many factors to come with the growing period that can affect. 

  • Field yields rarely give book yields until a farmer is experienced and competent.
  • Generically you want to reduce nitrogen as the plant wants to start to add weight to fruit or when flower truly bloom and no longer make buds but concentrate on the flowers.

If nitrogen uptake and assimilation is deficient during its stages of early development it will be problematic.

  • It is common for people to over nitrogen accumulate toxic levels which can be more problematic than under feeding.

Testing is only valid for the location and time period of each specific garden or farm.

  • Environmental, overall nutrition, management system, water frequency and type of nitrogen form makes your test unique to you.
    • Same crop, same size, same fertilizer but different location will equal different tests. 
    • Their is no golden number from a book, what you search for is the capability of "your" environment, plant, nutrition and you!




I have not seen better than the site grow weed easy illustrate and explain deficiencies so I wont try.

The identification of a problem is the easy part, addressing is easy enough but understanding the reason for the deficiency is important to ensure the issue is not repeated.

  • Generically speaking, nitrogen deficiency (not toxicity) often will not overly affect yield when only occurring in bloom but is illustrative of potential problems in transport (environmental stress? if current but often is result of earlier deficiency).
    • In terms of yellow plants ensure optimal P and enhance the limited photosynthesis you can to keep transport energy levels up more so than healthy plant.
    • Yellowing of leaves is not always caused by nitrogen deficiency but often is a common affect.

The reasons for a nitrogen problem is not always easy to pinpoint.  The following should lead you to the cause but understand deficiency and other problems are often in a domino effect.  Ensure to thoroughly understand the cause and how to prevent again.  If only fix the visible issue you potentially will see issues again.  Be diligent with this.

  • Check environment records,
    • Temperature (highs and lows and at period of growth)
    • Humidity
    • Light distance
    • Clean Air
    • C02?
    • OZ near plants?
  • Check nutritional records,
    • Check amounts and frequency of feeding
    • Check timing
      • issue after a particular feed?
      • If soil based.
        • Review recipe and ensure the % of nitrogen cycle breakdown is correct and all accounted for.
        • Annotate when you notice the issue and try to determine its starting period of time.
          • Next grow with similar soil make up either add fertilizers at that point next grow
          • or Adjust soil recipe increasing or decreasing the % and types of nitrogen as applicable.
      • Check growth period and ensure the nutritional recipe was correct.
        • Sometimes after an incorrect and/or too strong garden is given.
        • Make sure you identified the correct period of plant development.
          • This can happen during vacations or periods when focus is not on the garden.
    • Check % of nitrate and ammonia.
      • In hydro a reservoir fix is typically enough.
      • In soil a flush to doing re-pot may be necessary if the soil has become acidic (not meaning PH)
  • Check Media conditions,
    • wet, good or dry?
    • pest?
    • compact/loose media?
    • root bound?
  • Check Stress factors
    • Management factors
      • Top?
      • Tie down?
      • Accident?
      • Media humidity unstable?
      • Pest
      • Fungus/disease
      • Root damage
      • pesticide/fungicide?

The sum total of that information should enable you to adjust your nitrogen use from general to optimal ranges.



Nitrogen & Pollution

Nitrogen is a necessary ingredient but is also a very polluting one due to its mobile nature.  Small growers tend to not think of these aspects and thus the small farmers do play a large part in nitrogen run off issues which is currently being seen in urban settings.  In the future I can see the working on regulations that will financially impact this industry and will be with merited reasons but if farmers do not incorporate correct nutritional rates the farmer actually plays a role in the altering of waters due to increase nitrogen which tends to boost algae and other unfavorable unbalanced biological growth in our environment areas.  Often this is effect is unseen and largely under appreciated.

Growing our own foods is like a super power in terms of survival of a species.  Few creatures pull this off and with this altering comes a responsibility that humanity has not effectively embraced and thus we cause nature to suffer and only take noticed when forced via pollution effects of magnitude and/or regulatory controls which often have political slants that confuse the reduce the effectiveness of the issue.

Nitrogen pollution from farming of all sizes should be taken seriously as it is a big factor largely ignored because of special interest, politics and costs.  Their are and will be more emotional views of merit regarding this subject as time progresses and the issues becomes more necessary to address.  I suggest looking at all views and determining best from that as facts can become blurry as politics and political operatives do their work.

  • Some issues for farmers.
    • Often from a financial stand point chemical nitrogen fertilizers are more cost efficient due chemical made nitrogen having a higher % and reduced cost in volume in shipping and field distribution.
      • Generically written.
    • Due to this view, it should be understood that a farmer may have to embrace chemical fertilizers to remain financially viable in comparison to organic fertilizers but this is only one aspect of that overall consideration but is stated to give this perspective of organic and chemical nitrogen's use in farming. 
      • Sometimes people can question a farmer fertilizer choice not realizing if they did not they would potentially put at risk the farms profit or even lose money.




Union Break


Mandatory Union Break! and what you do on it is your business!




Nitrogen Properties and Fertilizer Use

  • Nitrogen cycle must be understood, video describes this cycle earlier in compilation
    • Ammonia volatilization is needed to be understood.  (the changing of ammonia to nitrite and then to nitrate.)

Anhydrous Ammonia (82% N)

  • In agriculture, anhydrous gaseous ammonia is compressed into a liquid and is applied under high pressure with a special implement by injection at least 15cm deep into a moist soil.
  • The ammonia gas reacts with water to form ammonium ions, which can be held to clay or organic matter.
  • If the ammonia is not injected deeply enough or soil is too wet or dry, ammonia can be lost by volatilization.
  • Anhydrous ammonia is usually the cheapest source of nitrogen,
    • Equipment and power requirements of the methods of application are specific and high.


Aqua Ammonia (21% N)

  • Aqua ammonia is ammonia dissolved in water under low pressure.
  • Aqua ammonia must be incorporated into land to avoid losses of nitrogen by ammonia volatilization;
    • Is not needed to be incorporated as deeply as anhydrous ammonia.


Urea (46% N)

  • Urea is the most widely used dry nitrogen fertilizer.
  • After application to soils, urea is converted into ammonia, which can be held in the soil or converted into nitrate.
  • Ammonia volatilization following fertilization with urea can be substantial, and if urea is applied to the surface of the land, considerable loss of nitrogen can occur.
  • With surface-applied urea, alkalinity of pH 9 or higher can develop under the urea granule or pellet, and ammonia will volatilize into the air.
    • Volatilization occurs on bare ground, on debris, or on plant leaves.
  • Urea is readily soluble in water, and rainfall or irrigation after its application move it into the soil and lessens volatilization losses.
  • Use of urease inhibitors has been suggested to lessen the volatilization losses of ammonia from surface-applied urea.
  • Manufactured urea is identical to urea in animal urine.

Calcium nitrate urea (calurea, 34% N, 10% Ca) is a double-compound fertilizer of calcium

  • Nitrate and urea to supply calcium and nitrogen
  • Several derivatives of urea are marketed as slow-release fertilizers.
    • Urea formaldehyde (ureaform, 38% N) is a slow-release fertilizer manufactured from urea and formaldehyde and is used
      for fertilization of lawns, turf, container-grown plants, and field crops.
      • Urea formaldehyde is also a glue and is used for the manufacture of plywood and particle board. 
    • Dicyandiamide (cyanoguanidine) (66% N) is a nitrogen fertilizer but is used most commonly as an additive (2% of the total N fertilizer) as a nitrification inhibitor with urea.
    • Sulfur-coated urea is a slow-release formulation (30–40% N) used as a fertilizer for field crops, orchards, and turfgrass
    • Isobutylidene diurea (IBDU) is similar to urea formaldehyde, but contains 32% nitrogen.
      • However, utilization of IBDU is less dependent on microbial activity than urea formaldehyde, as hydrolysis proceeds rapidly following dissolution of IBDU in water. Nitrogen is released when soil moisture is adequate.
      • IBDU is used most widely as a lawn fertilizer.
      • Its field use is to restrict leaching of nitrogen
    • Methylene ureas are a class of sparingly soluble products, which were developed during the 1960s and 1970s. These products contain predominantly intermediate chain-length polymers.
      • The total nitrogen content of these polymers is 39 to 40%, with between 25 and 60% of the nitrogen present as cold-water-insoluble nitrogen.
      • This fertilizer is used primarily in fertilization of turfgrass,
      • It has been used with other crops on sandy soils or where leaching of nitrate is an environmental concern.


Ammonium Nitrate (34% N)

  • Ammonium nitrate is a dry material sold in granular or prilled form. It can be broadcasted or side dressed to crops and can be left on the surface or incorporated. It does not give an alkaline reaction with soils; hence, it does not volatilize readily. However, incorporation is recommended with calcareous (high calcium soils) soils.
    • Ammonium nitrate is decreasing in popularity because of storage problems, e.g., with fire and explosion.
  • Calcium ammonium nitrate (ammonium nitrate limestone, about 20% N and 6% Ca) is a mixture of ammonium nitrate and limestone. This fertilizer is not acid-forming and is used to supply nitrogen and calcium to crops.


Ammonium Sulfate (21% N)

  • Ammonium sulfate is marketed as a dry crystalline material.
    • It is recommended for use on alkaline soils where it may be desirable to lower soil pH.
    • Nitrification of ammonium is an acidifying process.
      • Ammonium sulfate can be broadcasted or side dressed. It can left on surfaces or incorporated,
        • On calcareous (high calcium) soils watering in or incorporating is recommended to avoid ammonia volatilization


Nitrogen Solutions (28–32% N)

  • These fertilizers are mixtures of ammonium nitrate and urea dissolved in water.
  • In the solutions, half of the nitrogen is supplied as urea, and half is supplied as ammonium nitrate.
    • Because of the difficulties in handling, urea and ammonium nitrate should not be mixed together in dry form.
    • The solution acts once the dry materials are applied to the soil.
    • Ammonia volatilization may be substantial during warm weather, especially with surface application.
    • The solutions should be watered into the soil and should not be applied to foliage.


Ammonium Phosphates (10–21% N)

  • Ammonium phosphates are important phosphorus-containing fertilizers because of their high concentrations of phosphorus and water solubility.
  • Ammonium phosphates are made by reaction of ammonia with orthophosphoric acid (mono- and diammonium salts) or with superphosphoric (pyrophosphoric) acid
    • Diammonium phosphate (commonly 18% N, 46% P2O5) is a dry granular or crystalline material.
      • It is a soil-acidifying fertilizer and is useful on calcareous soils.
      • It should be incorporated into the soil.
      • It is a common starter fertilizer and is a common component of greenhouse and household fertilizers.
    • Monoammonium phosphate (commonly 11% N, 48% P2O5) has uses similar to those of diammonium phosphate.
    • Ammonium polyphosphate (10% N, 34% P2O5) is marketed as a solution.
      • Its use is similar to that of monoammonium phosphate and diammonium phosphate.

Double-salt mixtures

  • such as ammonium nitrate sulfate (30% N), ammonium phosphate nitrate (25% N), urea ammonium phosphate (25–34% N), nitric phosphate, and ammoniated superphosphate (8% N) (152).
  • These materials are used in the manufacture of mixed N-P-K fertilizers or for special needs in soil fertility.


Organic Nitrogen Fertilizers (0.2–15% N)

  • Most commercial varieties of organic nitrogen comes from other industry with waste plant and animal sources and are proteinaceous.
  • Organic nitrogen is typically more costly in terms of shipping and distribution in the field.
  • Organic materials range from less than 1 to about 15% N compared with the chemical sources.
  • Difficult for analysis.
    • Commercially organic fertilizers decline in usage with time.
    • Additionally the proteinaceous by-products of food processing have higher value as feeds for poultry and livestock than as fertilizers.
    • Demand for organic fertilizers remains, as organic farmers require these products in the maintenance
      of soil fertility on their cropland
  • The value of organic nitrogen fertilizers depends on their rate of mineralization, which is closely related to their nitrogen concentration). Generally, the more nitrogen in the fertilizer, the faster the rate of mineralization.
    • In bio farming methods such as natural farming/Korean farming microbes and fungus assist with this aspect more and that is a key ingredient to success to maintain mineralization at acceptable levels.


Recap Video



Understanding nitrogen correctly will enable you to manage your crops successfully.  By proper analysis it is possible to find your optimum nitrogen range for your unique location, plant and conditions.  When volumes of fertilizer are being used this can be a good cost effective means as the luxury level plants can hold without benefit to yield or quality is a wast of resources.

By understanding how to minimize leaching of nitrogen we also become better stewards of the land we have taken for our needs.


Credits & Respects too




~JJ the Gardener - A proud Cultural Healing and Life Compilation

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