Nutrient solutions

  • - Planting recommendations

    Album Vilmorin. The vegetable garden 1850-1895
    Album Vilmorin. The vegetable garden 1850-1895. Public Domain

    This article will show which plants can be cultivated in an aquaponic system. Before going into detail about the individual plants, however, it is important to understand which systems exist in the world of aquaponicsc, as some plants work better in system A than in system B, for example. Still others, on the other hand, have proven themselves in system B. This alone makes it clear that there is no such thing as the best system or the one system, and that when setting up or planning the design, you should pay close attention to which plants the system should be suitable for.

    First of all, however, it can be said: theoretically, any plant can be cultivated in an aquaponic system. However, there are some exceptions where conventional methods work better. More on this later in the individual categories.  In this article you will find a list of experiences with individual plants.

     

    Salads and herbs
    Salads and herbs are probably the group of plants that work best in aquaponics. They are usually weak growers and are well taken care of in the aquaponic system. I have personally experienced lettuces that have grown strong, thick and robust with the help of aquaponics, so that biting into a single leaf felt like biting into a juicy piece of meat. Really crunchy.

    What's more, lettuces and herbs will grow in any system, whether standing in gravel (Steady Flow / Flood & Drain), in planters both on polystyrene or similar (DWC) or in PVC pipe (NFT).

     

    Recommended varieties:

    Any lettuces such as chard, spinach, lettuce, iceberg lettuce, endive, rocket, purslane and so on have proved successful as have herbs such as basil, parsley, thyme and oregano.

     

    Not recommended:

    Mint should be avoided in the aquaponic system because it is rampant. It loves humid locations and is like paradise in an aquaponic system. Should it have its own system in isolation, there should be no problems, but together with other plants it will have overgrown them in no time.

     

     

    Fruit vegetables
    Fruiting vegetables belong to the group of highly nutritious plants and are also very popular in the aquaponic system. However, it should be borne in mind that some fruit vegetables can grow very large. Sufficient space above and below should be provided accordingly.

    Tomato plants, for example, grow enormously. I have heard of cases where the tomato plant has grown over eight (8!) metres tall. For most people, this should represent a height that either does not fit into the desired space or makes any care of the plant an impossible task. Alternatively, cocktail tomatoes or vine tomatoes can be planted, which usually remain much smaller.

    Cucumbers and other squash plants grow very wide and quickly overgrow the entire space. Here, too, thought should be given in advance to whether this space is available.

    Furthermore, not every system is suitable for fruiting vegetables. Neither a DWC nor an NFT system is normally capable of supporting such large plants. Theoretically, this is also possible, but it would have to be readjusted regularly with supporting measures, for example with ropes or other suspensions.

     

    Recommended varieties:

    I would recommend smaller fruiting vegetables, such as chilli plants or peppers, for private households. Smaller tomato plants, such as cocktail tomatoes, are also possible.

     

    Not recommended:

    Any cucurbits, tomatoes and other plants that grow very large should only be cultivated with caution in an aquaponic system. Due to the high nutrient content in the water, enormous results can theoretically be achieved, but practically only if there is enough space.

     

    Root and tuberous plants
    Botanically not quite correct, but certainly acceptable for understanding: I count plants that develop edible parts underground as root and tuber plants, such as potatoes, carrots, beetroot, ginger, turmeric, parsnips and the like.

    Theoretically, it is also possible to cultivate these plants in an aquaponic system, but some prerequisites are necessary here.

    Soft tubers, like potatoes, should not be planted in the gravel bed (Steady Flow / Flood & Drain), as the tuber would form around the gravel. This could cause enormous toothache when eaten. Instead, for soft tubers, the Aeroponics method has proved successful.

    With harder tubers, such as ginger and turmeric, the gravel bed is again possible, as their strength gradually pushes the gravel away.

     

    Recommended varieties:

    Ginger and turmeric I can recommend at this point, but only if there is enough space.

     

    Not recommended:

    Potatoes, carrots and other plants with relatively soft tubers I can only recommend if the necessary conditions have been created - see Aeroponic.

     

    Leek plants
    Leeks include the edible onion, the winter onion, the spring onion, chives, garlic, leeks and many more. All of these grow excellently in the aquaponic system.

     

    Recommended varieties:

    Depending on personal taste, pick one or two from the list of leeks that can grow alongside. They are easy to care for and the upper parts of the plants can be harvested several times during the year.

     

    Not recommended:

    Although onions and other leeks go well with almost any dish, care should be taken not to grow too many.

     

    Exotics
    As described above, theoretically any plant can be cultivated in an aquaponic system, as long as the necessary conditions are met. There are cases where even the cultivation of a banana and papaya plant has been successful in a specially constructed aquaponic system.

     

     

    Summary:
    Theoretically, any plant can be cultivated
    Salads, herbs and allium plants grow particularly well and are easy to care for.
    In the case of fruiting vegetables, it should be considered in advance whether there is enough space and room for them to develop.
    Root and tuberous plants are only recommended under certain conditions.
    Give free rein to creativity and inventiveness

     

    ID: 130

  • Aquaculture and Aquaponics

    Aquaculture is not aquaponics

    Actually, today we consume much more fish than there is in the oceans and lakes.

    Aquacultures in the seas and lakes are the basis for the high fish consumption. Today, aquacultures seem to be the solution at all to cover the high demand for fish, but there are also negative consequences for humans and the environment, especially for organisms living in the water. It is clear that more than half of all fish products consumed worldwide already come from aquaculture.
    UVIAquaponicSystem

    But what exactly is aquaculture? Aquaculture or aquafarming is the systematic breeding and catching of fish, seafood, etc. in freshwater or seawater. However, there is a big difference compared to traditional fishing. In traditional fishing, fish are taken from public waters, whereas in aquafarming the individual fish species are kept in separate net pens where they are bred, fed and then caught.

     

    This is done in the sea, in pens or in water tanks. The fish are therefore the property of the keeper and can only stay in their net enclosure, unlike fish that are fished in the traditional way. There are many additional problems in free-range farming: the unconsumed feed simply falls to the bottom in the sea and above a certain quantity this leads to undesirable reactions from the environment.

     

    The differences between the systems
    It is already clear that in aquaculture and hydroponics, environmental aspects and a higher production volume play a decisive role. The systems pollute the oceans and farmland less with by-products and can also be operated without being tied to a specific location. The difference is this: Hydroponics is for growing plants, aquaculture for breeding animals.

    In aquaponics, the two systems are combined to make the disadvantages of each work to the advantage of the other. Hardly any water is lost because the loops are almost closed - with the exception of the extracted material (obs, vegetables, fish, etc.), extremely little water leaves the system. This means that only a correspondingly small amount of water is actually used. In addition, fertiliser or nutrient solution does not have to be added to the system on a regular basis. Aquaponics can therefore also be described as a further development of aquaculture and hydroponics.

     

    Aquaponics - Combined systems
    Setting up an aquaculture system or a hydroponic system is not very complicated, and there are two possible approaches: to set them up separately or to build a combined system. In aquaponics systems, the advantages of the two systems described are simply combined. Plants are only grown in a substrate, the fish are kept in a large tank.

    A substitute for soil is expanded clay, even if it is not cheap. Gravel, rock wool, coconut fibre or other materials are also possible, but require some testing, as not all plants tolerate all variants equally.

    An essential part of the cycle is the collection tank for the hydroponic water in which the fish are ultimately kept. These are supplied with nutrients and oxygen by the plants. The excretions of the fish provide the plants with almost everything they need. The result is that, apart from a little water, no additives need to be used. The closed system works autonomously, except for a small water pump.

    So much for the theory, here is an interesting study by the South Westphalia University of Applied Sciences that shows the entire problem of such a system in real life.

    Picture: Principles of aquaponics - by Dr James Rakocy
    Context: 
    ID: 113

  • Chelated Micronutrients and their Benefits

    Ethylenediaminetetraacetic acid  ( EDTA ), also called  EDTA acid,  is an aminopolycarboxylic acid with the formula [CH2N (CH2CO2H)2]2 . This white, water-insoluble solid is widely used to bind to iron (Fe2+/Fe3+ ) and calcium ions (Ca2+), forming water-soluble complexes even at neutral pH.
     
    It is therefore used to dissolve the Fe- and Ca-containing scale and to release iron ions under conditions where its oxides are insoluble. EDTA is available as several salts, notably  disodium EDTA , sodium calcium edetate, and tetrasodium EDTA, but these all function similarly.
    Chelat Formel 
    Gefahrenzeichen
    Nutrient solutions consist of many mineral elements, most of which are either positively or negatively charged. Some of these mineral elements react with each other (the term is called precipitation: calcium reacts with phosphates and sulfates), which requires separate storage and administration. As a result, these individual compounds are no longer available to the plant. In some cases, even precipitates (A precipitate is a precipitate that forms when a solute separates from a solution.) can be visible and look like a fine white powdery substance that floats in the water or settles at the bottom of the reservoir.
    When the mineral elements precipitate, they become insoluble in water. However, they must be water soluble before they can be used by the plants (i.e., “bound in the nutrient solution”). Hydroponic nutrients consist of both macroelements (nutrients that the plants need in large amounts) and microelements (nutrients that the plants need in small amounts). These microelements tend to combine easily with the other elements, especially under conditions of high pH and/or when there is a high concentration of minerals.
     

    What is a chelated micronutrient?
    The chelation process basically forms a protective shell around the respective mineral element and creates a neutral charge. This keeps them from bonding together and becoming trapped in the nutrient solution. When two molecules of the same type surround a particular mineral, it is called a chelate . However, some chelate molecules are shaped like a letter 'C' and surround the mineral with only one molecule. This type is called a 'complex'. 

     

    Types of Chelates
    The chelate molecules require a bond (a type of glue) to bind them to the desired mineral element. There are a few binding agents that can be used for this, each of which has a different effect on the plants. 

     

    EDTA
    One of the most common forms of chelates is  ethylenediaminetetraacetic acid  (EDTA). Once the elements enter the plant, this very tight bond can become a problem. When absorbed by the plant, the EDTA can form bonds with other mineral elements. EDTA can help solve one mineral deficiency, but in some cases it can cause another. EDTA has even been known to take calcium directly from the cell walls of already formed plant tissue. This causes cellular damage to the plant. In cases where a significant amount of cellular damage has occurred due to calcium loss in this way, the plant cannot maintain enough water pressure ( keyword xylem ), which can make it look as if the plants are dying of thirst (wilting).

     

    Amino Acid Chelates
    Another type of chelate is the amino acid chelate. Amino acid chelates have a slightly less strong bond than EDTA chelates. Once the mineral is absorbed by the plant and released from the amino acid, the plant can use the leftover amino acid as a nitrogen source. Amino acid chelates are also often available for use in organic nutrient formulas and come in both liquid and dry forms.

     

    Glycine Chelates
    Another form of amino acid chelates are the glycine chelates. Just like regular amino acid chelates, once the glycine is separated from the mineral element in the plant tissue, the leftover glycine (amino acid) is used by the plant tissue. The glycine amino acids have an even smaller molecular size, so they are even more easily absorbed by the plants. This makes glycine chelates especially useful in foliar applications, as they pass through the plants leaf pores ( stomata ) more easily than other, larger molecular chelates.

     

    Summary
    Amino acid chelates are very safe for plants for both root uptake and foliar applications and only become toxic to the plant when severely overdosed. In general, however, care should be taken to avoid the toxic effects of EDTA chelates. Many experts advise against using chelated minerals that use sodium as a binding agent altogether. When looking for chelated minerals, it is best to look for ones that do not use sodium. These are readily available to the plants, ones that do not promote other deficiencies (like EDTA chelates), and ones that have organic certification.

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    ID: 593

  • Common Concentrations in Nutrients

    Orchilla Guano A A The great soil enricher
    Boston Public Library, Print Department

    The composition of hydroponic fertilizers is completely different compared to the fertilizers for earth cultures. Plants that are cultivated in soils require completely different fertilizer mixtures than hydroponics. As a guide: Organic fertilizers often need microorganisms (depending on their composition) to break down the nutrients for the plants. Inorganic fertilizers do not need microorganisms to be able to supply the plant with all nutrients. Of course, the following also applies here: the exception confirms the rule.

    Hydroponic fertilizers must be accountable for the special conditions of a hydroponics. These result on the one hand from the lack of microorganisms, which are required for the chemical splitting of the fertilizer substances in the soil - and can only be found there, on the other hand from the lack of buffering of the hydroponic system and from the fact that it is a closed system.

    Important boundary conditions include: Hydroponic fertilizers should not contain too many ballast salts (sodium, chloride, etc.). The ammonium and nitrogen content should not account for more than about 50% of the total nitrogen (N) supply in order to avoid acidification of the nutrient solution.

    However, this in turn does not apply to very hard (lime-rich) irrigation water. The phosphate content should also be significantly lower - compared to fertilizers for earth culture.

     

    Fertilizer with buffer effect / reservoir or so-called long-term fertilizer

    There are ion exchange fertilizers on the market for hydroponics. For decades, the ion exchange fertilizer “ Lewatit HD5 ” has been the only ion exchange fertilizer on the market. It was developed by Bayer AG in the 1970s and marketed under various trade names. The same company later developed the “ Lewatit HD5 plus ” for low-salt irrigation water (soft water).

    In the meantime, only the well-known Lewatit HD50 is manufactured. This should be optimized for every degree of hardness of the water. However, the manufacturer still recommends adding lime to soft water to ensure supply. 

     

    Which liquid fertilizer can you use?

    The range of liquid fertilizers and nutrient solutions has now become unmistakable (1). In addition to liquid fertilizers for the professional in larger containers, products are offered in smaller quantities for the hobby area. Mostly they are so-called universal fertilizers. However, some manufacturers also offer special fertilizers for hydroponics.

    Striking here: almost all manufacturers hold back with specific information about the plants for which the fertilizer should be "optimal. Likewise in dosing depending on the growth development. Even if certain plants are named by name, apparently not detailed here. If you think of tomatoes, you will probably not think of all 3,200 varieties that are currently being grown (source). To believe that one and the same fertilizer delivers consistently good results here also seems completely unbelievable to the layperson.

    1) You can find a (always) incomplete list of commercially available fertilizers here. We only keep this list as a list of ingredients for homemade nutrient solutions. You can find out how to do this here in detail using a sample mix. The series of articles begins here: Mix the hydroponic fertilizer yourself: introduction

     

    There are several ways to fertilize plants in hydroponics:

    • With liquid inorganic solid fertilizer, this is automatically added in large plants due to the conductivity measurement of the water.

    • By fertilizer salt release from solid ion exchanger granules.

    • Sludge up organic fertilizer or add such nutrient solutions.

    • A humus or compost layer that is applied to the top substrate layer in low-fiber systems and is only watered from above when fertilizer is required.

    Depending on the nutrient composition, the expected concentrations are of the following orders of magnitude:
     

    Compounds and trace elements / orders of magnitude in nutrient solutions

    K

    potassium

    0.5 - 10 mmol / L

    Ca

    Calcium

    0.2 - 5 mmol / L

    S

    sulfur

    0.2 - 5 mmol / L

    P

    phosphorus

    0.1 - 2 mmol / L

    Mg

    magnesium

    0.1 - 2 mmol / L

    Fe

    iron

    2 - 50 µmol / L

    Cu

    copper

    0.5 - 10 µmol / L

    Zn

    zinc

    0.1 - 10 µmol / L

    Mn

    manganese

    0 - 10 µmol / L

    B

    boron

    0 - 0.01 ppm

    Mon

    Molybdenum

    0 - 100 ppm

    NO2

    nitrite

    0 – 100 mg / L

    NO3

    nitrate

    0 – 100 mg / L

    NH4

    ammonia

    0.1 - 8 mg / L

    KNO3

    Potassium nitrate

    0 - 10 mmol / L

    Ca ( NO3 ) 2

    Calcium nitrate

    0 - 10 mmol / L

    NH4H2PO4

    Ammonium dihydrogen phosphate

    0 - 10 mmol / L

    ( NH4 ) 2HPO4

    Diammonium hydrogen phosphate

    0 - 10 mmol / L

    MgSO4

    Magnesium sulfate

    0 - 10 mmol / L

    Fe-EDTA

    Ethylenediaminetetraacetic acid

    0 – 0.1 mmol / L

    H3BO3

    Boric acid

    0 – 0.01 mmol / L

    KCl

    Potassium chloride

    0 – 0.01 mmol / L

    MnSO4

    Mangan (II)-Sulfat

    0 – 0,001 mmol/L

    ZnSO4

    Zinksulfat

    0 – 0,001 mmol/L

    FeSO4

    Eisen(II)-sulfat

    0 – 0,0001 mmol/L

    CuSO4

    Kupfersulfat

    0 - 0,0002 mmol/L

    MoO3

    Molybdänoxid

    0 – 0,0002 mmol/L
     
     

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    ID: 419

  • Fertiliser

    1884 Standard Fertilizer Companys Food for Plants

    Fertiliser programmes

    First of all: If you receive a fertiliser recommendation without having explained exactly which plants you are growing, you can safely ignore such recommendations. There are not hundreds of fertiliser types because there is one answer.
     
    Each plant species has individual nutrient requirements that also differ according to the growth phase it is in. Furthermore, indiscriminate fertilising, over-fertilising, under-fertilising, wrong composition etc. can have devastating consequences for many plants, ranging from undersupply to specific plant diseases. In order to achieve the best nutrient mixture for a specific plant, there is no getting around an analysis of the plant itself. For cost reasons alone, we recommend preparing the nutrient composition yourself.
     

     

    Mixing hydroponic fertiliser yourself ?

    The commercially available fertilisers consist of a complete fertiliser supplemented with macronutrients. They are offered by some hydroponics and/or fertiliser companies and vary depending on the hydroponic plant. An example of a fertiliser programme is the hydroponic tomato programme offered by Hydro-Gardens.

    In this programme, growers purchase Hydro-Gardens Chem-Gro tomato formula. It has a composition of 4-18-38 and also contains magnesium and micronutrients. To make a nutrient solution, it is supplemented with calcium nitrate and magnesium sulphate, depending on the variety and/or growth stage of the plant.

     

    Advantages of fertiliser programmes

    Programmes like these are easy to use. Minimal ordering of fertilisers is required (only 3 in the Hydro-Gardens example).
    Very little or no mathematical calculations are required to prepare nutrient solutions.
     

    Disadvantages of fertiliser programmes

    Fertiliser programmes do not allow for easy adjustments of individual nutrients. For example, if the leaf analysis shows that more phosphorus is needed. When using a fertiliser programme exclusively, it is not possible to simply add phosphorus.
    Another disadvantage is that fertiliser programmes do not allow farmers to take into account the nutrients already present in the water source. For example, if a water source has a potassium content of 30 ppm, there is no way to adjust the amount of potassium added in the fertiliser programme. And too much potassium can in turn block the uptake of other nutrients.

     


     

    Fertilizer programs can be more expensive than using
    Recipes for the production of nutrient solutions.

     

    Mix recipes for nutrient solutions / hydroponics fertilizer yourself

    There are also recipes for the production of nutrient solutions. The recipes contain a certain amount of each nutrient to be added to the nutrient solution. They are specifically available for a specific crop and in a variety of sources, e.g. B. at the university advice centers, on the Internet and in specialist journals. One example is the modified Sonovelds solution for herbs (Mattson and Peters, Insidegrower) shown below.
     

     

    Modified Sonneveld recipe / herbs

    element concentration
     Nitrogen 150 ppm 
     Phosphorus  31 ppm
     Potassium  210 ppm
     Calcium 90 ppm 
     Magnesium  24 ppm
     Iron  1 ppm
     Manganese  0.25 ppm
     Zinc  0.13 ppm
     copper 0.023 ppm
     Molybdenum 0.024 ppm
     Boron 0.16 ppm

     

    It is at the discretion of the breeder which fertilizers he uses to produce a nutrient solution according to a recipe. The fertilizers commonly used include:

    fertilizerDosage, contained nutrients
     Calcium nitrate 15.5 – 0 – 0.19% calcium
     Ammonium nitrate 34 – 0 – 0
     Potassium nitrate 13 – 0 – 44
     Sequestrene 330TM 10% iron
     Potassium phosphate monobasic 0 – 52 – 34
     Magnesium sulfate 9.1% magnesium
     Borax (laundry quality) 11% boron
     Sodium molybdate 39% molybdenum
     Zinc sulfate 35.5% zinc
     Copper sulfate 25% copper
     Magnesium sulfate 31% manganese
    Farmers calculate the amount of fertilizer in the
    nutrient solution based on the amount of a nutrient
    in the fertilizer and in amount specified in the recipe.

     

    Advantages of nutrient solution recipes

    Nutritional solutions allow fertilizers to be adjusted based on the nutrients contained in water sources. An example: A gardener uses a water source with 30 ppm potassium and produces the modified Sonneveld solution for herbs that requires 210 ppm potassium. It would have to add 180 ppm potassium ( 210 ppm - 30 ppm = 180 ppm ) to the water in order to obtain the amount of potassium required in this recipe.
    With recipes, nutrients can be easily adjusted. When a leaf analysis report indicates that a plant has iron deficiency. It is easy to add more iron to the nutrient solution.
    Since recipes make it easy to adapt, fertilizers can be used more efficiently than in fertilizer programs. Using recipes can be less expensive than using fertilizer programs.


    Disadvantages of nutrient solution recipes

    It has to be calculated how much fertilizer has to be added to the nutrient solution. (Link to performing calculations). Some people may feel intimidated by the calculations involved. However, the calculations only require uncomplicated mathematical skills based on multiplication and division.
    A high-precision scale is also required for the measurement of micronutrients, since the required quantities are very small. Such a scale can be found on Amazon from 30.- €: e.g .: KUBEI 100g / 0.001g.

     

    This is about the calculation of nutrient solutions for your own needs

    Picture: Boston Public Library is licensed under CC BY 2.0

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    ID: 415

    URL

  • Fertiliser: Calculation of nutrient solutions

    Orchilla Guano
    By Boston Public Library, license CC BY 2.0

    Calculation of the concentrations of nutrient solutions using the following two equations

    The calculation of the amount of fertilizer that has to be added to the nutrient solutions is part of a successful hydroponic production. Only multiplication, division and subtraction are used for the calculations; no advanced mathematical knowledge is required.

    If you want to know more about the compositions and concentration information, the article series can be too Stoichiometry and a look at the conversion of Mol and grams When specifying the concentration of the individual elements and connections, it is helpful to better understand the complexity of the topic.

    If you master the general process, producing nutrient solutions and adjusting the amount of nutrients is child's play.

    Fertilizer recipes for hydroponics are almost always given in ppm (in the long form: parts per million). This may differ from the fertilizer recommendations for growing vegetables and fruits outdoors, which are generally given in lb / acre (pounds per acre).

    First you have to convert ppm to mg / l (milligrams per liter) using this conversion factor: 1 ppm = 1 mg / l (1 part per million corresponds to 1 milligram per liter). For example, if 150 ppm nitrogen is required in a recipe, 150 mg / l or 150 milligrams of nitrogen in 1 liter of irrigation water are actually required.

    Ppm P (phosphorus) and ppm K (potassium) are also used in recipes for nutrient solutions. This also differs from the fertilizer recommendations for growing vegetables and fruits in the field, which use P2O5 (phosphate) and K2O (potash). The fertilizers are also given as phosphate and potash. Phosphate and potash contain oxygen, which must be taken into account in hydroponic calculations. P2O5 contains 43% P and K2O contains 83% K.

    Let us check the previous circumstances:

    1 ppm = 1 mg / l
    P2O5 = 43% P
    K2O = 83% K

    Nutrient solution tanks are usually measured in gal ( gallons ) in the United States. When we convert ppm to mg / l, we work with liters. To convert liters into gallons, use the conversion factor of 3.78 l = 1 gal ( 3.78 liters corresponds to 1 gallon ). The invoice is also given below for continental interested parties.

    Depending on the scale you use to weigh fertilizers, it may be useful to convert milligrams into grams: 1,000 mg = 1 g ( 1,000 milligrams correspond to 1 gram ). If your scale measures in pounds, you should use this conversion: 1 lb = 454 g ( 1 pound = 454 grams ).

     

    Let us summarize these circumstances:

    3.78 l = 1 gallon
    1000 mg = 1 g
    454 g = 1 lb


    Now we have all the necessary circumstances. Let's look at an example.

    How do you determine how much 20-10-20 fertilizer is needed to deliver 150 ppm N with a 5 gallon tank and a fertilizer injector that is at a concentration of 100:1 is set?

    First, write down the concentration you know you want to reach. In this case it is 150 ppm N or 150 mg N / l.

     150 mg N / 1 L Wasser

    Note that we multiply by 1. This allows you to cancel the units that are the same in the numerator and denominator. Now we can paint "mg N" and get the unit g N / l water.

    150mg1LWasser 3

    Continue this process by converting liters into gallons. Most containers are still traded in gallons ( 3.78 liters ). Entertaining here: the metric system was invented by the Britten. If you want a metric result, omit this calculation step.

    150mg1LWasser 5

    Now there are only grams of nitrogen left per gallon of water.
    We'll get closer to it. Now we want to convert grams of nitrogen into grams of fertilizer. Remember that our fertilizer is a 20-10-20, which means that it contains 20% nitrogen. It can be imagined that 100 grams of fertilizer contain 20 grams of nitrogen. 

    150mg1LWasser 6

    So where do we stand now? We calculated how many grams of fertilizer are needed in each gallon of irrigation water. At the moment we have a normally strong solution. Our example prompts us to calculate a concentrated solution of 100: 1. This means that for every 100 gallons of water that are applied, 1 gallon of stock solution is also applied via a fertilizer injector. We also know that our storage tank holds 5 gallons. Below see calculation for metric system (liters).

    In gallons

    150mg1LWasser 8

    In the calculator: 150 x 1: 1000 x 3.78 x 100: 20 x 100 x 5 is 1417.5 grams on 5 gallons of water (in the storage tank)

    After we have deducted everything, we have a gram of fertilizer left. This is the amount of fertilizer we need to put in our storage tank to apply 150 ppm N at a concentration of 100: 1. Multiply and divide and you get the answer 1417.5 grams of fertilizer.

    In liters

    150mg1LWasser de

    In the calculator: 150 x 1: 1000 x 100: 20 x 100 x 10 is 1500 grams per 10 liters of water ( in the storage tank )

    After we have deducted everything, we have a gram of fertilizer left. This is the amount of fertilizer we need to put in our storage tank to apply 150 ppm N at a concentration of 100: 1. Multiply and divide and you get the answer 750.0 grams of fertilizer.

    This means that for every 100 liters of water that is applied, 1 liter of stock solution is also applied via a fertilizer injector. We also know that our storage tank holds 10 liters. 

    If we measure in pounds, we have to put 0.75 kg / 1.15 lb fertilizer in our storage tank to apply 150 ppm N with a concentration of 100: 1.

    You have just completed one of the two equations. Now let's look at the other one.

    We just found that we need to add 750 grams of fertilizer to deliver 150 ppm nitrogen at a concentration of 100: 1. The fertilizer we used was a 20:10:20. In addition to nitrogen, we also add phosphorus and potassium. With the next equation we determine how much phosphorus we supply. This is basically the reversal of the first calculation.

    We start with the amount of fertilizer that we put in our tank. The final units are ppm or mg / l. As with the previous calculation, we use our specifications until we receive these units.

    1417gDuengerWasser 0

    Multiply with the concentration of the nutrient solution.

    1417gDuengerWasser 2

    Multiply to convert to liters.

    1417gDuengerWasser 3

    Next, convert milligrams of fertilizer into milligrams of phosphate.

     1417gDuengerWasser 4

    Next we will convert grams of phosphate into grams of phosphorus, assuming that phosphate contains 43% phosphorus.

    1417gDuengerWasser 5

    Finally, we convert grams of phosphorus into milligrams of phosphorus.

    1417gDuengerWasser 6

    When we calculate this, we find that we have added 32.25 mg / l P or 32.25 ppm P. This is the second equation. We can also use them to determine how much potassium we have added. 

    1417gDuengerWasser 7

    We added 124.5 mg / l K or 124.5 ppm K.

    With these two basic calculations, you can use any nutrient solution recipe program. How they are used to calculate a recipe can be seen in this article:

     

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  • Fertilizer & Nutrient Solutions

    Use the Homestead Bone Black Fertilizer
    Use the Homestead Bone Black Fertilizer by Boston Public Library, CC BY 2.0

    Here we have created a short introduction to the topic of fertilizer and nutrient solutions, with which you can learn the concept, the basics and also the calculation of self-created nutrient solutions. In the last article you will find a brief overview of deficiency symptoms and how you can recognize and correct them. 

    Please also keep in mind that the perfect recipe for your own plant requires enormous knowledge, complex technology and a lot of experience. However, for many areas this is not necessary at all. If you, as an entrepreneur, are in competition and have to work to the optimum in order to be profitable, things look different. But this little guide is not aimed at entrepreneurs who need to make money with it. For commercial applications, please do not hesitate to take advantage of our experience, our knowledge and the technology required for this:  just ask us - email or phone call is enough.

    A brief introduction to fertilisers & nutrients

    Fertiliser: Calculation of nutrient solutions

    Fertilizer: Calculate a nutrient recipe

    Fertilizer: Essential Nutrients, Function, Deficiency and Exces

    Common Concentrations in Nutrients

    To ensure a highly optimised nutrient supply throughout the entire growth process, you need analytical equipment. Here a short overview and Selection.

    Kontext: 

    ID: 407

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  • Fertilizer: Essential Nutrients, Function, Deficiency and Exces

    Deficiency symptomsHubbard Squash Rices seeds are the best

    Before we begin discussing the principles of plant nutrient systems in hydroponic systems, we need to define what we mean by "hydroponic."

    Hydroponics is the process of growing plants in water containing nutrients. Examples of this type of hydroponic systems are NFT (Nutrient Film Technique) systems and deep water floating systems where the plant roots are placed in nutrient solutions. Another definition of hydroponics is growing plants without soil. According to this definition, growing plants in soilless media (potting soil) or other types of aggregate media such as sand, gravel, and coconut shells are considered hydroponic systems. Here we use the term hydroponics for growing plants without soil.

     

    Essential nutrients

    Plants cannot function properly without these 17 essential nutrients. These nutrients are needed to allow the processes important to plant growth and development to take place. For example, magnesium is an important component of chlorophyll. Chlorophyll  (see picture) is a pigment that serves to capture light energy needed for photosynthesis. It also reflects green wavelengths and is the reason most plants are green. Magnesium is the center of the chlorophyll molecule. The table below lists the functions of the essential nutrients for plants.

    Basic structure for chlorophylls a, b and d (The designation of the rings is given.)


    Essential nutrients can be broadly divided into macronutrients and micronutrients . The classification macro (large) and micro (tiny) refers to the amounts. Both macronutrients and micronutrients are essential for the growth and development of plants. Macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, sulfur, calcium, and magnesium. Micronutrients include iron, manganese, zinc, boron, molybdenum, chlorine, copper, and nickel. The difference between macronutrients and micronutrients lies in the amount plants need. Macronutrients are needed in larger amounts than micronutrients. Table 1 shows the approximate content of essential nutrients in plants.

    Plants obtain carbon, hydrogen and oxygen from air and water. The remaining nutrients come from the soil or, in the case of hydroponics, from nutrient solutions or aggregate media. The sources of nutrients available to plants are listed in Table 1.

     

    Essential components of nutrient solutions, Table 1

    Nutrient (symbol) Approximate plant content (% dry weight)

    Role in the plant

    		 Source of nutrients available to the plant
    Carbon (C), hydrogen (H), oxygen (O) 90+ % Components of organic compounds Carbon dioxide (CO 2 ) and water (H 2 O)
    Nitrogen (N) 2–4% Component of amino acids, proteins, coenzymes, nucleic acids Nitrate (NO3-) und Ammoniak (NH4+)
    Sulfur (S) 0.50% Component of sulphur-containing amino acids, proteins, coenzyme A Sulfate (SO4-)
    Phosphor (P) 0.40% ATP, NADPMetabolic intermediates, membrane phospholipids, nucleic acids Dihydrogenphosphat (H2PO4-), Hydrogenphosphat (HPO42-)
    Potassium (K) 2.00% Enzyme activation, turgor, osmotic regulation Potassium (K + )
    Calcium (Ca) 1.50% Enzyme activation, signal transduction, cell structure Calcium (Ca2+)
    Magnesium (Mg) 0.40% Enzyme activation, component of chlorophyll Magnesium (Mg2+)
    Manganese (Mn) 0.02% Enzyme activation, important for water splitting Manganese (Mn 2+ )
    Iron (Fe) 0.02% Redox changes, photosynthesis, respiration Iron (Fe 2+ )
    Molybdenum (Mo) 0.00% Redox changes, nitrate reduction Molybdat (MoO42-)
    Copper (Cu) 0.00% Redox changes, photosynthesis, respiration Copper (Cu 2+ )
    Zink (Zn) 0.00%
    Cofactor activator for enzymes
    Alkohol-Dehydrogenase, Carboanhydrase
    		 Zink (Zn2+)
    Bor (Bo) 0.01% Membrane activity, cell division Borat (BO3-)
    Chlor (Cl) 0.1–2.0% Charge equalization, water splitting Chlor (Cl-)
    Nickel (Ni) 0.000005–0.0005% Component of some enzymes, biological nitrogen fixation, nitrogen metabolism Nickel (Ni2+)

     

     
    To get an idea of ​​the quantities required, here is a fertilizer quantity recommendation from the BISZ for sugar beet in arable farming. From the quantity you can see that, for example, 90 grams of copper per 1 ha (10,000 m 2 ) is only a tiny amount per square meter and a fraction of that is needed per plant. In this example: 0.009 grams per square meter. But if this element is completely missing, the plant cannot grow at all because it is essential for photosynthesis (see table above). When dry, it (copper) is no longer found due to chemical processes during drying.
     
    Nutrient requirement kg/ha
    Nitrogen 250
    Phosphor 100
    Potassium 400
    Magnesium 80
    Sulfur 20 – 30
    Calcium 60 – 80
    Nutrient requirement g/ha
    Bor 450 – 550
    Manganese 600 – 700
    Ferrum 500 – 1.500
    Copper 80 – 90
    Zinc 250 – 350

     

    PH value

    It is impossible to talk about plant nutrition without considering pH. Hydroponics is primarily concerned with the pH of the water used to prepare nutrient solutions and irrigate plants. pH is a measure of relative acidity, or hydrogen ion concentration, and plays an important role in the availability of plant nutrients. It is measured using a scale of 0 to 14 points, with 0 being the most acidic, 7 being the most neutral, and 14 being the most alkaline. The scale is logarithmic, and each unit corresponds to a 10-fold change. This means that small changes in values ​​​​mean large changes in pH. For example, a value of 7 is 10 times higher than 6 and 100 times higher than 5. In general, the optimal pH range for growing vegetables in hydroponics is 5.0 to 7.0.

    This diagram shows the relationship between nutrient availability and pH value:

    Graphic: Pennsylvania State University

     

    At the bottom of the chart, various pH levels between 4.0 and 10.0 are indicated. At the top of the chart, the relative acidity or alkalinity is indicated. Within the chart, the relative nutrient availability is represented by a bar. The wider the bar, the more relatively available the nutrient is. For example, the nitrogen bar is widest at a pH of 6.0 to 7.5. This is the pH at which it is most available to plants. Between 4.0 and 4.5, it is very narrow and not as easily available to plants.

    It is also important to consider the alkalinity of the water. Alkalinity is a measure of capacity. It measures the ability of the water to neutralize the acid. This is primarily due to the combined amount of carbonate (CO3) and bicarbonate (HCO3), but hydroxide, ammonium, borate, silicate and phosphate can also contribute.

    When total alkalinity is low, the water has a low buffering capacity. As a result, the pH changes slightly depending on what is added to the water. When total alkalinity is high, the pH of the water is high. To lower a high pH of the water, acid can be added to the irrigation water. The amount of acid needed depends on the alkalinity of the water.

     

    Nutrient antagonism and interactions

    For example, a hydroponic tomato nutrient solution recipe calls for 190 ppm nitrogen and 205 ppm potassium. Due to an error in calculating the amount of fertilizer to use, 2,050 ppm potassium is added. An excess of potassium in the solution can cause antagonism with nitrogen (and other nutrients) and result in nitrogen deficiency even if 190 ppm nitrogen was added. The table below lists common antagonisms.

     

    NutrientAntagonist of
    Nitrogen Potassium
    Phosphor Zinc
    Potassium Nitrogen, calcium, magnesium
    Sodium Potassium, calcium, magnesium
    Calcium Magnesium, Bor
    Magnesium Calcium
    Ferrum Manganese
    Zinc Ion competition: high concentrations of heavy metals, copper and phosphate reduce the uptake rate of zinc: the cause of zinc deficiency in the plant does not necessarily have to be zinc-poor soil

    See also: Interactions

     

    Problems with nutrients

    Hydroponic systems are less forgiving than soil-based systems, and nutrient problems can quickly lead to plant problems. This is why nutrient solution composition and regular monitoring of the nutrient solution and plant nutrient status are critical.

    The minimum law

    Carl Sprengel's law of the minimum states that the growth of plants is limited by the resource that is relatively scarce (nutrients, water, light, etc.). This means that a lack of nitrogen can also lead to the plant not being able to process other nutrients. On the other hand, too much of one component can have undesirable consequences: for example, too much lime inhibits the absorption of nutrients.

     

     Also pay attention to the symptoms of
    Deficiency symptoms  that often point out problems:

    Here is a brief overview of the deficiency symptoms, which can vary depending on the plant genus. 

    Symptoms N P K Ca S Mg Fe Mn B Mo Zn With  Overfertilization
    Upper leaves yellow         X   X            
    Middle leaves yellow                   X      
    Lower leaves yellow X X X     X              
    Red stems  X  X X                     
    Necrosis     X     X   X X     X  
    Points               X          
    Shoots die                 X        
    White leaf tips           X         X    
    Crumpled Wheatgrass X X X                    
    Rolled yellow leaf tips                         X
    Twisted growth                 X        


    Damage caused by soluble salts

    Cause: Soluble salt damage can be caused by over-fertilization, poor water quality, accumulation of salts in aggregate media over time, and/or inadequate leaching. Fertilizers are salts, and in hydroponic systems they are the most common fertilizer. As water evaporates, soluble salts can build up in aggregate media if they are not adequately leached. Irrigation water can also have high levels of soluble salts, contributing to the problem.

    The symptoms: Chemically induced drought can occur when the content of soluble salts in the planting substrates is too high. The result is that the plants wilt despite sufficient watering. Other symptoms include dark green foliage, dead and burned leaf edges and root death.


    Detection: Soluble salt levels can be monitored/measured by tracking the electrical conductivity (EC) of irrigation water, nutrient solutions and leachate (a nutrient solution drained from the plant container).

    Correction: Soluble salts can be leached out with plain water. First, determine the cause of the high soluble salts level and correct it. 

     
    Boron Bo
     
    The cause:  deficit in the fertilizer mixture.
     
    The symptoms:  Insufficient flower formation, the flowers are smaller and deformed. Boron deficiency affects the apical meristems (growth points). Sometimes the meristem dies completely and the side shoots start to grow (broom effect). The meristems have shorter internodes, which are often thicker and show small and deformed leaves at the tip. The shorter internodes sometimes lead to dwarfism. The stems often have breaks and cracks. The fruits are sometimes deformed and corked. Cracks or spots are also possible. Older leaves can show necrosis.
     
    Detection: leaf analysis.
     
    Correction :  Fertilizers containing boron: Borax or boric acid, but note that boric acid is highly toxic. Alternatively: If there is a general nutrient deficiency, complete fertilizers that also contain boron can be used.
     
     
     
    Boron toxicity Bo
     
    The cause: Boron toxicity is caused by too much boron applied to plants. Of the nutrients commonly applied as fertilizers, boron has the narrowest margin between deficiency and toxicity. It is easy to apply too much boron. Check the calculations of fertilizers before applying them and check again. It can also be found in irrigation water. It is important to check the boron level in a water source before use and to take into account the boron in the water when adding boron fertilizer.
     
    The symptoms: Symptoms of boron toxicity are yellow and dead spots on the leaf edges. Reduced root growth can also occur.
     
    Detection: Monitor the media and perform plant analysis.
     
    Correction : Determine the source of the excess boron and correct it.
     
     
     
    Calcium deficiency Ca
     

    The cause:  Strong temperature changes can interrupt and hinder calcium uptake. Lack of light, cold and/or too humid environmental conditions. Fertilizer level too low. Calcium deficiency can be caused by under-fertilization, a nutrient imbalance or a pH value that is too low. It is also related to moisture management, high temperatures and low air circulation. Calcium is a mobile nutrient and is transported through the plant in the water-bearing tissues. Fruits and leaves compete for water. Low relative humidity and high temperatures can lead to an increased transpiration rate and increased transport to the leaves. In this case, a calcium deficiency can develop in the fruits.

    The symptoms:  The apical meristems (these are the dividing tissues of the plant) are deformed and die off without any noticeable symptoms on the oldest leaves. The upper part of the stem and flower bud may bend. Small and deformed leaves on the upper side. Unusually dark green leaves. Premature flower and fruit drop. After a deficiency, the leaves that were developing at the time of the deficiency often show a typical deformation/drying out or a white edge. This is called tip burn and is particularly common in lettuce and strawberries. Browning of the inside of a stem/head, around the growing point like in celery (black heart). Typical symptoms are also blossom end rot on peppers and tomatoes. Symptoms usually first appear as brown leaf edges on new plants or on the underside of the fruit. Blossom end rot in tomatoes and peppers. As symptoms progress, you may see brown, dead spots on the leaves. A lack of sufficient calcium can lead to rot.

    Detection: Leaf analysis. Fruits have a poorer shelf life.

    Correction :  Make sure the pH is between 5.5 and 6.5. Add calcium nitrate or calcium chloride depending on whether you need the extra nitrogen or not. 

    In the greenhouse: Increase the temperature. More light. Without wind, the plant's nutrient transport is reduced - ensure air movement in the greenhouse. 

    Ferrum deficiency Fe
     
    The cause: The most common cause of iron deficiency is high pH in the media and/or irrigation water. It can also be caused by nutrient imbalance.
     
    The symptoms: Iron deficiency in plants shows itself as yellowing between the leaf veins. Note that this symptom appears first on new growth.
     
    Detection: Monitor the media and perform plant analysis.
     
    Correction : Correct the pH of the nutrient solution. If necessary, add iron fertilizer.
     
     
     
    Sulphur deficiency S
     

    The cause:  Too little or incorrectly proportioned fertilizer. A pH value that is too low also blocks the absorption of sulfur. At a pH value of 4.0, sulfur absorption stops completely. Too little magnesium.

    The symptoms:  Extensive yellowing  of the leaf tissue and the leaf veins. Often the younger parts of the plant first and later the whole plant. Symptoms are more likely to appear in young or freshly growing leaves at the top of the plant. Sulfur is an immobile nutrient. This means that sulfur can only be re-disposed (transported) relatively slowly by the plant. Lime green to yellow discoloration on leaves is characteristic of sulfur deficiency. It starts at the leaf stalk and moves to the leaf edges and tip. As the disease progresses, the entire leaves first turn yellow, then later brown and necrotic and then die completely. Sometimes purple/reddish leaf stalks on the affected leaves or even a purple stem. The symptoms of a mild deficiency are usually limited to the top of the plant. The middle part of the plant is hardly affected, lower leaves almost never.

    Detection: leaf analysis.

    Correction :  increase the fertilizer dose. Correct the pH: keep it well above 4.0. 5.5 to 6.5 is a good average for many plants. Enrich the soil with Epsom salt / magnesium sulfate / MgSO 4 : one teaspoon per 2 liters of water (approx. 1% concentration).

    Nitrogen deficiency N

    The cause: Nitrogen deficiency can be caused by under-fertilization, nutrient imbalance or excessive leaching.
     
    The symptoms: Typical first symptoms of nitrogen deficiency are light green foliage and a general stunting of the plants. Wilting and dead and/or yellow leaf edges can also be observed. Yellowing of the entire leaf, including the leaf veins, can be seen. The older leaves turn yellow first, but the nitrogen deficiency quickly leads to a general yellowing. Necrosis or deformation of leaves or stems does not appear in the initial stage.
    General growth retardation.
     
    Detection: Measuring/monitoring the electrical conductivity (EC) of nutrient solutions can help prevent nitrogen deficiency. Adjust the EC value if it is too low or too high.

    Correction : Determine the cause and correct it. This may mean adding more nitrogen to the nutrient solutions. It may also mean there is too much of an antagonistic nutrient in the nutrient solution.
     
     
    Potassium deficiency K
     
    The cause:  incorrectly dosed nutrient solution. Plant consumption higher than calculated: a potassium deficiency often occurs in crops that bear a large amount of fruit.
     
    The symptoms:  Wilting of the plants even at moderate temperatures. Leaf edge necrosis on the oldest leaves. Browning and curling of the lower leaf tips and yellowing (chlorosis) between the leaf veins. Purple spots may appear on the underside of the leaves. Yellowing: Yellowing also begins on the edges of the oldest leaves and develops towards the middle of the leaf. In some cases the leaf edge is not affected and the necrosis begins inside the leaf between the leaf veins.

    Detection:  Nutrient analysis and/or perform plant analysis.
     
    Correction :  Re-dose. Check antagonist concentration: nitrogen, calcium, magnesium
     
    Note: Too much potassium can cause severe stunting, redness, and poor germination. Excessive amounts of potassium can also make it difficult to absorb other ions such as calcium. 
     
     
     
    Copper deficiency Cu
     
    The cause:  incorrect fertilizer composition.
     
    The symptoms:  White discoloration in the tips of the younger leaves. The leaves curl up in a corkscrew shape. Later they may die (necrosis).
    The youngest leaves have difficulty unfolding. The youngest leaves curl up and wilt. Necrosis at the youngest growing points and the leaf margins of the youngest leaves.
     
    Correction :  Add special copper fertilizer.
     
     
     
    Magnesia deficiency Mg
     
    Cause: Magnesium can be caused by a high pH of the medium and/or a nutrient imbalance between potassium, calcium and nitrogen.
     
    The symptoms: Yellowing of the leaf tissue. The leaf veins remain green. This yellowing begins on the oldest leaves. Look for yellowing between the leaf veins as a symptom of magnesium deficiency: chlorosis or yellowing. Magnesium deficiency usually shows up first on the lower to middle leaves, which makes it easier to distinguish from iron deficiency. Premature leaf drop of the affected leaves. Sometimes the discoloration can be more brownish than yellow.
     
    Detection:  Nutrient analysis and perform plant analysis.
     
    Correction : Correct the pH of the nutrient solution. If necessary, add magnesium fertilizer. Check the dosage of competing cation suppliers (K, Ca and N).
     
     
    Manganese deficiency Mn
     
    Cause:  Too little or no fertilizer. Manganese deficiency is somewhat similar to iron deficiency: chlorosis between the leaf veins. Light green net on the leaves. It can also be confused with magnesium deficiency. With a manganese deficiency, the leaf veins (including the smaller veins) remain green, but the green stripes remain very narrow.
    With a magnesium deficiency, these green stripes around the veins are wider and the finest leaf veins also turn yellow.
     
    The symptoms:  Distinct network of green veins. Sometimes occurs on young, but already fully developed leaves (middle leaves).
     
    Correction :  Add special manganese fertilizer. Increase fertilizer dosage.
     
     
    Molybdenum deficiency Mo
    The cause:  Too little or no fertilizer. Many symptoms of a molybdenum and nitrogen deficiency are similar. The plant cannot use and process nitrogen without molybdenum.
     
    The symptoms:  The plants are smaller and show a pale green color. The discoloration can develop into yellowing first on the edges and then between the main veins. The leaf disk disappears almost completely, only the main vein of the leaf remains with small pieces of leaf. This main vein is usually also wavy. (whipstick symptoms). The leaves remain smaller and sometimes take on a spoon-like shape: wavy edge and curved main vein.
     
    Correction :  Add special molybdenum fertilizer.
     
    Phosphorus deficiency P
     
    The cause:  The pH value may not be in the optimal range of 5.5 to 6.5. There may also be an imbalance of nutrients. Check the antagonist zinc dosage. In cold periods, a build-up of sugar in the leaves can show the same symptoms as a phosphorus deficiency.
     
    The symptoms:  stunted and spindle-shaped growth, reduced leaf size and reduced number of leaves. Dull grey-green leaves with red pigments in the leaves. The phosphorus deficiency is mainly evident in the characteristic reddish to purple leaf discolouration, first on older leaves, and often the leaf veins are also affected.
    General growth retardation. Poor root development. Smaller plants than usual.
     
    Detection:  pH control and dosage monitoring. Nutrient analysis.
     
    Correction : Correct the pH value of the nutrient solution. If necessary, reduce the zinc content in the nutrient solution.
     
    Note:  An excess of phosphorus can result in a deficiency of trace elements such as Zn, Fe or Co.
     
    Zinc deficiency Zn
     
    The cause: Possibly too high a phosphorus content in the nutrient solution or too little zinc in the nutrient solution.
     
    Symptoms: The  following symptoms may occur: Chlorosis: yellowing of the leaves. Depending on the species, young leaves may be the most affected, while in others both old and new leaves are chlorotic. Necrotic spots: partial or total death of leaf tissue in areas of chlorosis. Leaf bronzing: chlorotic areas may turn bronze. Retarded plant growth: this may occur as a result of a decrease in growth rate or a decrease in the internode (the length of the shoot between two nodes). Dwarf leaves: small leaves that often show chlorosis, necrotic spots or bronzing. Malformed leaves: leaves are often narrower or have wavy edges.
     
    Detection: Monitor media and/or perform plant analysis.
     
    Correction : Correct the pH value and/or the amount of phosphorus if you know that there is enough zinc in the nutrient solution. Otherwise, add zinc in small doses. Remember: copper and phosphate reduce the absorption of zinc!
    ID: 418
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  • Interactions with minerals

    Interactions and interrelationships in mineral metabolism

    Individual nutrients interact with each other. Depending on their composition in the solution, a competitive situation can arise: An excess of one nutrient blocks the absorption of another (antagonism). The opposite is also possible: certain nutrients promote the uptake of other elements (synergism). Conversely, this means that if certain substances are missing or are present in too low a concentration, absorption of the desired substances is not possible at all or only incompletely.

     

    The Table provides an overview of the most frequent Interrelationships.

     Cause Action 
     

    impedes absorption (antagonism)

    promotes absorption (synergism)
    NH4 (Ammonium)  Ca, Mg, K P, SO4
    NO3 (Nitrat)  P Ca, Mg, Mn, K
    Ca (Calcium)  Mg, Fe, B, Mn  
    K (Kalium) Ca, Mg, NH4 (Ammonium) NO3 (Nitrat)
    Mg (Magnesium) Ca P
    Mn (Mangan) Mg, Fe, Zn, NH4 (Ammonium), B NO3 (Nitrat)
    Cl (Chlor) P, NO3 (Nitrat) Ca
    Na (Natrium) Ca P
    P (Phosphor) Fe (Ca, B, Cu) Zn
    Cu (Kupfer) Fe, B  
    SO4 (Sulfat) Mo Ca
    Zn (Zink) P  
    Optimal supply of: 
    B (Bor)   K, Ca, P
    Ca (Calzium)   K (Viets-Effekt 1)
    Lack off:  
    B (Bor) K, Mg, P = Carbohydrate stagnation  
    Ca (Calcium) K  
    Überschuss an:
    Ammoniak Calcium  
    Kalium Calcium  
    Magnesium Calcium  
    Natrium Calcium (2)  

     

    1) Viets effect

    On the function of calcium (Ca) in the cell wall: homogalacturonan of the pectins are bound together via Ca (= junction zones); suppresses the uptake of unwanted cations (Na+; Cd2+; Mn2+); prevents the leakage of sugars, amino acids and K+; promotes internal uptake, especially at acidic pH (Viets effect);

    2) EC value

    Too high a sodium value (manifested in a high EC value) can make calcium uptake more difficult or even block it completely.

     

    Context: 

    ID: 58

  • Measurement of concentrations

    First we look at the nutrient solutions, some of which have been around for over a hundred years. This shows us in which concentrations the measurement must take place. 

    This serves as an initial orientation as to what nutrients or elements must be contained in a solution. A further step is to closely observe plant growth in order to be able to identify deficits as such.

    The next step is to get an idea of ​​which elements, and therefore which compounds, are in the end product. Unfortunately, such an analysis (the plant is put into a blender and additional chemicals are added depending on the compounds we are looking for) has the disadvantage that it doesn't really reveal everything that interests us. This is because the chemical compounds can rarely be found in the plant in the form in which they were originally added. This is where biology comes into play. The only example that we would like to mention here is the citric acid cycle, which we do not want to withhold from you. It illustrates the complexity of metabolism.

    Citric acid cycle

     

    Nutrition of hydroponic plants

    When grown in containers, the plants are nourished by an aqueous solution of inorganic nutrient salts. Since the chemical properties of the soil differ greatly from their natural state due to the lack of fine organic soil components, normal plant fertilizer is only partially suitable for hydroponics.
    A special hydroponic fertilizer can help, which uses additives to buffer the pH value of the solution in a range suitable for many plants. So-called ion exchange granules are also used for this purpose, which supply the plants with nutrients through ion exchange and at the same time bind minerals such as lime that are present in the water in excess and are incompatible with the plants.
    The microbial conversion of ammonium ions into nitrate ions consumes oxygen that is lost to root respiration. Hydroponic fertilizers therefore use less ammonium salts as nitrogen fertilizer and more nitrates.
    In hydroponics, the electrical conductivity of the nutrient solution is usually constantly monitored. If the concentration of dissolved substances increases (for example through exudates or extraction from soil), the solubility for oxygen in the nutrient solution decreases. If solutions are too concentrated, it becomes more difficult for the plants to absorb water (see also osmosis). Different stages of the plant also require different conductivity of the nutrient solution depending on the variety, cuttings around 0.2-0.4 mS/cm, which can increase to 2.4-2.6 mS/cm until fruit formation . The morphology of plant growth also depends on the concentration of the nutrient solution, for example whether squat plants grow or stretched ones. If the nutrient solution is too concentrated, it can be diluted with deionized water or rainwater.
    Depending on the nutrient composition, the expected concentrations are in the following orders of magnitude:
     

    Compounds and trace elements / orders of magnitude in nutrient solutions

     K

    Potassium

    0.5 - 10 mmol/L

     Approx

    Calcium

    0.2 - 5 mmol/L

     S

    Sulfur

     0.2 - 5 mmol/L

     P

    Phosphorus 

    0.1 - 2 mmol/L

     Mg

    Magnesium

    0.1 - 2 mmol/L

     Fe

    Iron

    2 - 50 µmol/L

     Cu

    Copper

    0.5 - 10 µmol/L

     Zn

    Zinc

    0.1 - 10 µmol/L

     Mn

    Manganese

    0 - 10 µmol/L

     B

    Boron

    0 - 0.01 ppm

     Mo

    Molybdenum

    0 - 100 ppm

     NO2

    Nitrite

    0 – 100 mg/L

     NO3

    Nitrate

    0 – 100 mg/L

     NH4

    ammonia

    0.1 - 8 mg/L

     KNO3

    Potassium nitrate

    0 - 10 mmol/L

     Ca(NO3)2

    Calcium nitrate

    0 - 10 mmol/L

     NH4H2PO4

    Ammonium dihydrogen phosphate

    0 - 10 mmol/L

     (NH4)2HPO4

    Diammonium hydrogen phosphate

    0 - 10 mmol/L

     MgSO4

    Magnesium sulfate

    0 - 10 mmol/L

     Fe-EDTA

    Ethylenediaminetetraacetic acid

    0 – 0.1 mmol/L

     H3BO3

    Boric acid

    0 – 0.01 mmol/L

     KCl

    Potassium chloride

    0 – 0.01 mmol/L

     MnSO4

    Manganese (II) sulfate

    0 – 0.001 mmol/L

     ZnSO4

    Zinc sulfate

    0 – 0.001 mmol/L

     FeSO4

    Iron(II) sulfate

    0 – 0.0001 mmol/L

     CuSO4

    Copper sulfate

    0 - 0.0002 mmol/L

     MoO3

    Molybdenum oxide

    0 – 0.0002 mmol/L
     
    In order to convert the quantities (mg, ppm, mol, etc.) we have created some articles for you here. You can also find corresponding "stoichiometry" calculators online, such as here:  https://www.omnicalculator.com/chemistry/ppm-to-molarity
     
     
     

     

     

    Here are some recipes for nutrient solutions...

     
    Nutrient solution according to Wilhelm Knop
    One liter of finished solution contains:
    1.00 g Ca(NO 3 ) 2  calcium nitrate
    0.25 g MgSO 4  * 7 H 2 O magnesium sulfate
    0.25 g KH 2 PO 4  potassium dihydrogen phosphate
    0.25 g KNO 3  potassium nitrate
    traces of FeSO 4  * 7 H2O iron(II) sulfate
    Medium according to Pirson and Seidel
    One liter of finished solution contains
    1.5 millimol KH 2 PO 4
    2.0 mM KNO 3
    1.0 mM CaCl 2
    1.0 mM MgSO 4
    18 μM Fe-Na-EDTA
    8.1 μM H 3 BO 3
    1.5 μM MnCl2 _
     
    Culture medium according to Epstein
    One liter of finished solution contains
    1 mM KNO 3
    1 mM Ca(NO 3 ) 2
    1 mM NH 4 H 2 PO 4
    1 mM (NH 4 ) 2 HPO 4
    1 mM MgSO 4
    0.02 mM Fe-EDTA
    0.025 mM H 3 BO 3
    0.05 mM KCl
    0.002 mM MnSO 4
    Trace elements:
    0.002 mM ZnSO 4
    0.0005 mM CuSO 4
    0.0005 mM MoO 3
     
    Trace element additive according to DR Hoagland (1884–1949)
    One liter of finished solution contains
    55 mg Al 2 (SO 4 ) 2
    28 mg KJ 28 mg
    KBr
    55 mg TiO 2
    28 mg SnCl 2  · 2 H 2 O
    28 mg LiCl
    389 mg MnCl 2  · 4 H 2 O
    614 mg B(OH ) 3
    55 mg ZnSO 4
    55 mg CuSO 4  · 5 H 2 O
    59 mg NiSO 4  · 7 H 2 O
    55 mg Co(NO 3 ) 2  · 6 H 2 O
     
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  • Nutrient solution: The simplest Solution

    Here is a recipe for small systems that supply tomatoes, peppers and leafy vegetables:
     
    Ingredients
    Base with micronutrients/trace elements: Masterblend 4-18-38 Hydroponic Fertilizer: this is still missing magnesium sulfate and calcium nitrate.
    One kilo costs about 30 to 49 euros and is enough for about 1500 liters of nutrient solution
     
    Magnesium sulfate: Epsom Salt
    One kilo costs about 5 euros 
     
    Calcium nitrate: PowerGrow Calzium Nitrate 15.5-0-0
    One kilo costs about 24 euros 
    Recipe
    Mix the ingredients in the following ratios: (2:1:3). You must not mix all the ingredients together .
    To do this, take two containers (bottles) of 500 ml each. This will prevent the calcium nitrate from reacting with the phosphate and precipitating.
     
    Fill the first bottle with 120 grams of NPK fertilizer and 60 grams of magnesium sulfate. If you use warm water (preferably deionized or distilled), the components dissolve better. Remember that tap water already contains calcium and magnesium. Depending on the water hardness, you should reduce the amount of calcium and magnesium. One °dH corresponds to 10 mg CaO (calcium oxide) per liter of water.
     
    Contents  division
     120 grams of Masterblend 4-18-38 (about 1/2 cup and a tablespoon) 
     60 grams of magnesium sulfate (about 4 tablespoons)
    		  Solution 1: mix with 500 ml water
     180 grams of calcium nitrate (about 3/4 cup)  Solution 2: mix with 500 ml water
     
     
    Use / Concentration
     Plant  concentration 
     Fruit-bearing bedding plants
     Solution 1: 3 ml per liter of water: for 10 liters take 30 ml, for 1 gallon = 12 ml
     Solution 2: 3 ml per liter of water: for 10 liters take 30 ml, for 1 gallon = 12 ml
     Green leafy vegetables  Solution 1: 2.5 ml per liter of water: for 10 liters take 25 ml, for 1 gallon = 8 ml
     Solution 2: 2.5 ml per liter of water: for 10 liters take 25 ml, for 1 gallon = 8 ml
     
    When mixing the nutrients, pay attention to whether the plants show any signs of deficiency. Read more here: Signs of deficiency.
    If you have an EC or TDS meter, the concentration should be between 1.5 and 2.0 EC. Read more here: EC and pH values ​​of plants.
     
    * ) Conversion
    1 US gallon = 3.78541 liters = 231 cubic inches (inch³)
    1 liter = 0.26417 US gallons
    1 American gallon = 4 American quarts = 8 American pints = 3.785411784 liters
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    ID: 595
     

  • pH and Ec: Cannabis

    Nutrients that cannabis needs can be divided into three categories: Primary macro-nutrients, secondary macro-nutrients and micro-nutrients. This division is based on how much of each nutrient the plant needs.

    Nitrogen, for example, is categorised as a primary nutrient because the plant needs more of it than calcium or sulphur, for example.  Cannabis has different nutrient requirements in different phases. Nitrogen, for example, is mainly needed in the growth phase, but much less in the flowering phase.

    On the other hand, the need for other nutrients, such as phosphorus, increases. In the growth and flowering fertilisers from well-known manufacturers, the nutrients are already optimally adapted in each case. (You can find more about the correct fertilising depending on the phase of life further down in the text).

     

     

    You can find a more comprehensive and filterable overview in the pH & Ec Finder here...

     

    Phase PPM (Hannah) EC (mS/cm2) PPM (Hannah) EC (mS/cm2)
    Early Growth 350 - 400 ppm 0,7 - 0,8 400 - 500 ppm 0,8 - 1
    Seedling 400 - 500 ppm 1 - 1,2 500 - 600 ppm 1 - 1,3
    Transition 550 - 650 ppm 1,3 - 1,5 600 - 750 ppm 1,2 - 1,5
    Vegetative Stage 1 650 - 750 ppm 1,6 - 1,7 800 - 850 ppm 1,6 - 1,7
    Vegetative Stage 2 750 - 800 ppm 1,7 - 1,8 850 - 900 ppm 1,7 - 1,8
    Vegetative Stage 3 850 - 900 ppm 1,8 - 1,9 900 - 950 ppm 1,8 - 1,9
    Flowering Stage 1 900 - 950 ppm 1,9 - 2 950 - 1000 ppm 1,9 - 2
    Flowering Stage 2 950 - 1050 ppm 2 - 2,2 1000 - 1050 ppm 2 - 2,1
    Flowering Stage 3 1050 - 1100 ppm 2,2 - 2,3 1050 - 1100 ppm 2,1 - 2,2
    Flowering Stage 4 1100 - 1150 ppm 2,3 - 2,4 1100 - 1150 ppm 2,2 - 2,3
    Flushing 0 - 400 ppm 0 - 0,8 0 - 400 ppm 0 - 0,8

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    ID: 145 

  • Photometry

    Ruby transmittance
    Von FDominec, CC BY-SA 4.0    
    UV-VIS-NIR-Transmissionsspectrum
    of a one cm thick Rubin-Cristall

    Photometry

    Context: in aqua- and hydroponics there is no getting around measurements of nutrients as well as "pollutants". Photometry is the cheapest and most precise solution to this problem. It is actually only useful for professional use, as the acquisition costs are between 2,500 and 16,000 euros. A suitable device such as the Hach DR 6000 photometer costs about 13,000 euros (as of 2022-10). The cost of a measurement is between 2 and 15 euros, depending on the substance. However, this device is one of the most sophisticated measuring devices, it is already considered a "Porsche" among measuring devices - especially in terms of the speed of analysis.
     
     
    Photometry refers to all light-based measurement procedures that are carried out with a photometer (a light source with clearly defined values).
    photometer (a light source with clearly defined values).
    Photometry is based on the principle that each dye absorbs specifically at a certain wavelength depending on the concentration and the layer thickness.This relationship is described in Lambert-Beer's law.

     

     

     
    A photometer always has the same structure:
     
    • Light source
    • Monochromator
    • Sample in cuvette
    • Detector

    The sample
    The light now passes through our sample with a certain initial intensity I0. This is in a cuvette. A cuvette is a sample container that is transparent to allow the measurement. Substances always appear in the complementary colour to the absorbed colour. There are the following requirements for the sample:
     
    • The solution containing the sample must be homogeneous: it must be clear and not milky.
    • The sample should absorb light at the measured wavelength.
    • The concentration should be low, because at high concentrations Lambert-Beer's law no longer applies.
    • Now the light passes through the sample, loses intensity and therefore only has intensity I.

     

     

    Extinction as a central value

    What is extinction?

    The absorbance is the decadal logarithm of the ratio of the initial intensity and the intensity after sampling. The concentration can be determined by the loss of intensity.

    Extinction should not be confused with absorption. Extinction includes all light-attenuating events. The following light-attenuating events can occur in our sample:

    • The absorption of the wavelength by the molecules of the sample in the solution,
    • the refraction of light in an inhomogeneous, milky solution on the particles of the sample,
    • the reflection on the liquid surface or the cuvette.

    Preparation of the sample

    In order to specifically measure absorption, the following things must be taken into account:

    • The sample must be well dissolved: There should be no more particles floating around that would make the sample milky or inhomogeneous.
    • A calibration measurement must be carried out with the cuvette and the solvent. This means that the solvent (usually water) and the cuvette must be placed in the photometer and calibrated. (Press the Calibrate button).

    The photometer now measures the extinction again. However, since no dye is included, only the reflection on the water and on the cuvette is measured, which is subtracted from the extinction in the subsequent measurements. If these steps are followed, you can successfully measure the absorbance together with the extinction.

    Photometry and Lambert-Beer's law

    What does extinction tell us? Lambert-Beer's law applies here. This represents the extinction in connection with our substance, its concentration and the layer thickness of the optical medium. The layer thickness is, so to speak, the width of the cuvette, which is usually standardized to 1 cm. If the layer thickness remains constant, as does the molar, decadal extinction coefficient (absorption of the corresponding wavelength), there is a linear function here. This line increases as the concentration of the sample in the solution increases.

    This allows the concentration of the substance being sought to be determined. Note: Lambert-Beer's law only applies at low concentrations of the "dye". Thus there is a natural upper limit for the extinction. As an example, let's assume our solution is completely black, so no more light comes through. If you add more dye, the concentration increases, but no light comes through the solution for measurements anyway.

    In reality, there is no material that exactly fulfills Lambert's law. In particular, the radiance of any surface has a directional dependence and this changes as the direction from which the surface is illuminated changes. Even standards that are used to calibrate measuring devices can only be well described by Lambert's law in certain reflection directions and wavelength ranges. At wavelengths outside the visible spectral range and at reflection or illumination directions of more than a few 10° to the vertical, deviations of several 100% from Lambert's law can occur, even with normal ones. [1]

     

    Creating a spectrum with a photometer

    As a rule, to determine the concentration of an analyte in the sample, it is sufficient to measure the extinction or absorption of the solution. However, if you want to characterize your analyte more precisely, you may have to record a spectrum.

    As a rule, the extinction is measured individually for each wavelength at a specified concentration and layer thickness. However, since one does not want to carry out a calibration for every wavelength, modern spectrometers are used today that take on this task independently. Spectral analysis is an important method for identifying and/or determining the concentration of unknown substances.

     

    UV/VIS spectroscopy

    When we talk about spectra, we are no longer talking about photometry, but rather about spectroscopy or, more precisely, UV/VIS spectroscopy. The name comes from the fact that these spectra are recorded from the UV (Ultra Violet) to the visible (Visible) range of light.

    UV/VIS spectroscopy is based on measuring the absorbance of visible and ultraviolet light by the sample. The spectral, ie wavelength-dependent, information can be obtained either by selecting and scanning the wavelength of the incident light in front of the sample (see dual-beam spectrometer) or by separating the wavelengths of the transmitted light after the sample (diode array spectrometer). The ratio of the spectral intensity of the transmitted and incident light provides the transmission spectrum. The logarithmic reciprocal of the transmission gives the extinction spectrum.

    Basically, extinction provides information about absorption, scattering, diffraction and reflection on and in the sample. Phenomena of radiation absorption are often evaluated in UV/VIS spectroscopy, since the photon energy of visible and ultraviolet light corresponds to the transition energy of the states of outer electrons of many atoms and molecules. By absorbing photons in the visible and ultraviolet spectral range, valence electrons (e.g. those in the p and d orbitals) can be excited, that is, transformed into a state of higher energy. The transmission or extinction spectrum therefore allows the identification and quantitative determination of analytes. 

    Here is an overview of spectrophotometers and HowTo's.

    [1]  Andreas Höpe, Kai-Olaf Hauer: Three-dimensional appearance characterization of diffuse standard reflection materials. In: Metrologia. Band 47, Nr. 3, April 2010, S. 295–304, doi:10.1088/0026-1394/47/3/021.

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