Added by on 2017-09-07

On todays episode we are going to talk about Organic Fertilizers and what and how to calculate NPK. According to Colorado State University an organic fertilizer refers to a soil amendment derived from natural sources that guarantees, at least, the minimum percentages of nitrogen, phosphate, and potash.  Examples include plant and animal by-products, rock powders, seaweed, inoculants, and conditioners. By definition these products have to guarantee at least a known amount of Nitrogen Phosphorus and Potassium or NPK So what is NPK? NPK refers to the percent weight of that Nitrogen Phosphorus and Potassium makeup of the material in question. Generally the industry standard is to consider include the entire weight of the organic molecule as a part of this weight. Using Nitrate as an example the % weight includes the Nitrogen and three Oxygen atoms that make up N03 Nitrogen is available in three forms. Ammonia, Nitrate and Nitrite. NH3 NO3 and NO2 Phosphorus is most commonly found in P2O5 and Potassium in K2O. So if you have results that represent the elemental numbers such as the lab results we have been presenting recently you will have to convert them to generate your NPK numbers so that you can compare then. The first step to do this is to figure what percent the N P and K make up of their organic forms. This is done using the atomic weight of the element in questions. The atomic weight generally represents the weight of the individual of each atom. Each atom on the periodic table has a different weight. Meaning for K2O there is one oxygen and two potassium atoms to total weight of K2O is: Total weight: (39.10*2) + 16 = 94.2 In order to figure out what % the nitrogen is simply divide potassiums combine atomic weight by […]

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20 Comments

  • dennisservaes 1 week ago

    I think I'm getting scared. Do I suffer from homophobia?

  • Hydroponic City 1 week ago

    whats up buddy? i need some advice. i have tomato plants that are just beginning to flower. what is a good npk ratio to use so my tomatoes turn out and i get max fruits? please note i have them growing in coco fiber in a one gallon bucket. i have been using a 7:12:40 hydroponic fertilizer plus cal nitrate and mag sulfate plants look really healthy, should i continue with this or add something else? let me know your suggestions please also veteran advice from others are welcome. thanks all

  • WhatAmI IsItInMe 1 week ago

    im about to start experimenting with bioponics, in replace of fish with compost and worm castings. do you think a NPK tester would be the way to go with monitoring the nutrient levels ?

  • Darshit Vasava 1 week ago

    i have a question i need a calculation nitrogen percentage to kg/akkar  or kg/hactor.
    if a fertilizer contains 2% of nitrogen then what would be the calculation please reply soon as possible

  • David D 1 week ago

    I'm looking forward to next videos thanks Steven.

  • Rob Bob's Backyard Farm & Aquaponics 1 week ago

    Great background clip Stephen..
    Cheers mate.. 

  • Jim S 1 week ago

    Fantastic series. Looking forward to your upcoming analysis's .

  • Growing with Joe 1 week ago

    Stephen, Nice video. This is good information to know. 

  • wildchook (Mary) 1 week ago

    Thank you for sharing the NPK info Stephen. Great vid shared!

  • DonnaldaSmolens 1 week ago

    I love your precision in these videos.  You also make these things a bit more understandable to the non scientist.  Looking forward to the results.  thank you

  • Alberta Urban Garden Simple Organic and Sustainable 1 week ago

    Have you ever wondered what organic fertilizers and NPK are?  Today we take a look at them prior to presenting lab results for used coffee grounds, coffee and comfrey!

    #organic #organicfertilizer #NPK #nitrogen #potassium #phosphorus #usedcoffeegrounds #coffeegrounds #coffee #comfrey

    http://youtu.be/gdcD-G-wBjY

  • HuwsNursery - Grow Organic Produce Inexpensively 1 week ago

    Thanks Stephen for the information I've definitely learnt many things from it! Can't wait to see the results in the upcoming videos 🙂

  • Randall Nortman 1 week ago

    I think your math is slightly off for correcting for the molecular weight vs. the elemental.  To convert from elemental weight to molecular weight, you multiply the elemental weight by the ratio of molecular weight to elemental weight.  In your example, the ratio of molecular weight of K2O to elemental weight of K is 94.2/78.2 = 1.20.  So you should be multiplying by 1.20 instead of 1.1699, so 20,000 mg/kg elemental K would be corrected to 24,000 mk/kg K2O, or 2.4%.  It's a small difference in this case, but the farther that ratio is from an even 1.0, the bigger the difference will turn out to be.

    To put it in roughly algebraic terms:

    MolecularPPM = ElementalPPM * (MolecularWeight / ElementalWeight)

    ElementalPPM = MolecularPPM * (ElementalWeight/MolecularWeight)

    https://en.wikipedia.org/wiki/Labeling_of_fertilizer#Converting_nutrient_analysis_to_composition

  • Chris Towerton 1 week ago

    @ 1:22 Ahrr "Milligrams per Kilograms"… I love that phrase, rolls off the tongue, like peas off a chopstick 😉 Sadly, I'm not clever enough to keep up with you on the rest of this ;-p
    Oh wait! @ 3:22 "Milligrams per Kilograms", there it is again… he,he,he I'm back with you 🙂 At this moment, I have never more fully understood being Homer 😉 oxox 

  • Patrick Meehan 1 week ago

    I have collected many kilos of coffee grounds ,. Being winter and with hard frost ground I have not used to CG yet. I am looking forward to your coffee ground video. Thanks for the sharing the NPK details

  • OYR Frugal & Sustainable Organic Gardening 1 week ago

    Thanks for sharing how you're converting your lab results to standard NPK values. I look forward to seeing the NPK of coffee and comfrey.

  • Double Dog Farm 1 week ago

    Looking forward to the used coffee grounds video. 

  • MrMac5150 1 week ago

    Though a shovel of manure and coffee grounds, leave the rest to nature & god.

  • MrMac5150 1 week ago

    Keep it simple…..loosing you.

  • Keyplayr61 Greenhouse Hydroponics And Gardens 1 week ago

    Looking forward to all the next series on this, Stephen!