NPK Fertilizer Numbers - what they really mean
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- Опубликовано: 5 авг 2024
- Most online gardening information get this wrong. Find out what NPK fertilizer numbers really mean.
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NPK Fertilizer Numbers - what they really mean
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Images:
All slides and videos belong to GardenFundamentals.com or are public domain images, except for the following:
burning phosphorus: www.angelo.edu/faculty/kboudr...
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potassium in water : commons.wikimedia.org/wiki/Fi... 
Хобби
I love gardening and chemistry so this video was like an early birthday present for me! I saw this video first so now I'm off to watch the one you recommended at the end. Thank you so much!
Thanks for pointing out the obvious we all overlooked. Now it’s time for me to watch your other videos.
Well well 5 10 10 etc they are best understood as proportions of compound rather than elemental weight
Really good information. Really knowledgeable and clearly explained. Thank you
Absolutely love your channel! Your presentation reminds me of my botany professor from years ago. Sharing and liking thank you,
Good video. I never knew this before. Thanks for enlightening me.
This is a great video. I have been trying to understand plants more and this helped a ton. Extremely clear and simple.
I'm sure others have pointed it out but at 4:23 you said phosphorus but you meant potassium. I mix them up when I talk all the time.
I personally appreciate learning what's true vs what's easy to understand. Knowledge is power, and knowledge builds upon itself. The more you more, the more you will know.
Thank you for providing factual info.
Keeping it real! Love this dude.
Whoa! I didnt even think about it like that! 🤩
But I do have a question:
This is greatly assuming that the proportions of the NPK containing molecules are all equal in the fertilizer, e.g. a 3lb bag of fertilizer contains 1lb of N containing molecules, 1lb P containing molecules and so on.
So here's my question:
Do fertilizer companies not balance the NPK molecules so that their product can reflect the NPK numbers they claim?
Just came across your video and have to admit that I was surprised that all those prestigious companies and especially universities are getting it so wrong. An excellent explanation and the net figures are spot on. Happy that I watched the video. Thank you.
i respectfully disagree with you on this. as an engineer and a farmer myself i dont see any problem with the way they sell fertilizer. This guy just to the gardening into a chemical lab. He simply said that if you buy a bag of 120lb fertilizer with 10-10-10 you will not get 10% of nitrogen which equates to 12lb of "pure nitrogen". Of course everyone knows it, in that 12lb of "nitrogen" will be mix of a few elements that have nitrogen element in it. He went on doing chemical equation calculating "exact" nitrogen amount it has. Even with that he is still very wrong because 10% advertisement could depend of lots of things like quality of the fertilizer and what kind of mixture that is. if he wanted "precision" he should go to chemical lab to buy pure chemical to put on :). it is very irrelevant to me :)
Very informative video. Thank you for the clarification of the numbers. Knowing the difference is so beneficial. Chemistry is important too. I recently found out that using dolomite garden lime can be detrimental to calcium absorption in tomato and pepper plants. A home gardener who has a Ph.D. in Genetics and Plant Breeding mentioned using calcium nitrate for his tomatoes and pepper plants. I asked him about BER, blossom end rot, and mentioned what amendments I use in my homemade potting mix, which dolomite lime was one of them to reduce the acidity of peat moss. His reply was that dolomitic lime contains magnesium. Mg is a metal similar to calcium but has a stronger charge than calcium. It can replace the calcium and cause BER. I am going to add calcium nitrate to my tomato and pepper plants to see if it will help with BER.
Have used 10-10-10 all my life in my vegetable garden, no issues so far. No soil test done either.
This is why if you keep fish using your water change on your plants is so helpful. All the bad stuff in your tank is great stuff in your garden or potted plants.
When the Ag Extension Service says add X pounds of K per 1000 sq ft. is that the compound or adjusted number?
Pavlis knows what he is talking about. Thank you Sir.
thank you for covering this, i learned this at A&M but completely forgot. that being said of course they didn't make a big deal about it as they should have and should be, most of those professors have the mentality of just replace the plant rather than really be able to save the plant. more money worse teaching apparently. but i digress.
Hello just discovered your channel. I have already learned a great deal especially in relation to soil and fertilization. Your arguments have allowed myself to be open to the use of synthetic fertilizers where in the past I was primarily organic in my approach. While I do raise vegetables and flowers I am very interested in improving my lawn. Been investigating Jonathan Green products as they are readily available and their philosophy with respect to lawns is also a combination of both approaches with the eventual goal of mostly organic inputs. This seems in agreement with your approach as well. So I am wondering would you ever do an episode on the establishment, care and feeding of lawns?
I have been thinking about that - not done yet.
This convention varies with countries the US is as you say, some other countries use the direct elements This make it a nightmare buying fertilizers from abroad
Thanks for this info. Happy growing from Detroit. 👍
Thank you for this. So when we use Miracle grow on our potted plants and say it has the correct 3-1-2 ratio of NPK that plants need is that correct? Are the plants using the phosphate and potash in that ratio or does the ratio actually apply to the amount of phosphorus and potassium?
Klaus
If the numbers are written as a ratio, then they are P2O5 and K2O. So a 3-1-2 is P2O5 and K2O.
@@Gardenfundamentals1 thank you, that has been troubling me for a while now!
Thank you Mr. P. 🌺💚🙃
Nice video. Thanks!
wow I wish I could attend a class like your videos... It is probably hard to assimilate with just viewing. This would have to be immersed completely to realize the benefits.
The country where I live has a regulation that fertilizer "grading", or labelling, must include the concentration of elemental NPK in an additional number in brackets after the ratio.
For example 3:1:5 (18), which would mean 18% of the product weight is pure NPK.
In the above example 1kg fertilizer would have 180g pure elemental NPK, which is divided into 9 parts (3+1+5). This means 1 part is 20g, which works out to 60g N (3 parts x 20g), 20g P (1 part x 20g) and 100g K (5 parts x 20g) per 1kg product.
Still takes some calculation, but at least the average person is able to work it out without needing to know the molar masses or atomic weights of compounds and elements.
This also help to gauge at a glance how "strong" the fertilizer is, a 3:1:5 (36) would be twice as concentrated as a 3:1:5 (18) and should be used in a halved dosage.
what country is that?
Worthless info. Wasted some of my time only because I realized non of content had info of value for my gardening success.
What an excellent video
So I recall in another video uou say the ideal fertilizer ratio for plants is 3-1-2. Given the 10-10-10 is really close to the 3-1-2, is it ideal for plants as a general fertilizer? I’m a bit confused now.
i think all that matters to consumers is to follow fertilization advice , if the packet says to use xyz then xyz is used .
What? No mention of Avogadro’s number?? 😅 Great video with great explanation! Thank you!
Hello, I have a query, what I can understand you are not calculating N value in molecular weight as it is already in N form, but, what if I have a fertilizer which has nitrogen in Nitrate (NO3-) or Ammonia (NH3) form, do I need to convert the N value then by the same method you have shown in this video? e.x. for Ammonia to get correct N value do I need to deduct molecular weight of 4 Hydrogen atoms from NH3 to get correct number of N value in Ammonia?
no - the value on the fertilizer is already a Nitrogen number - not a nitrate number.
Why we don't correct Nitrogen too, since it is in form NO3 or NH4? Could you show us how you correct P and K? The mathematics?
actually he explains it in reply to another comment. Basically the N number represnt the actual nitrogen , so they did the calcualtion for you for nitrogen only.
Brilliant!
That’s knowledge!
OK
Basically: 6:38
but are those completely bio available as such or are it just recalculated chemical equilibria
Thx
Telling it like it is and it's the way I like it, thank you it makes me smile 😁
In southern Florida, the soil is naturally high in phosphate. So I need a fertilizer of the form X-0-X. It is difficult to find a fertilizer that is not for lawns(high nitrogen) with zero phosphate. I am growing vegetables. I had to go online to find something close to what I need. I found 10-0-6 which is the best fit for my soil. This fertilizer is still called for lawn applications. Seems low in Nitrogen for lawns.
This video is a very good introduction of pure inorganic chemistry to an understanding of fertilizer content. One might ask why to the fertilizer companies sell bags containing 10:10:10 in addition to bags containing 16:16:16, NPK
not really sure - it does not make sense.
Thanks for clarifying.
The problem then becomes, since most people get soil tests through their extension agency, which is usually (always?) affiliated with universities such as the ones you called out as incorrectly explaining fertilizer content, should a gardener assume that their soil test recommendations use the terms "phosphorus" and "potassium" correctly? I suspect (but don't know for sure) that the recommendations continue to use the terms incorrectly, and so there's no need to do a conversion. It's truly unfortunate that these institutions haven't standardized this terminology.
All soil tests should clearly state what they are recommending. If it is not clear - ask.
I just looked up some sample test reports on Google and some say: use X lb/acre P2O5, and others say use X lb/acre P.
Speaking generally, I could see how something this routine could slip someone's mind over time. People probably get used to short hand and procedures where there isn't a lot of utility in explaining it over and over.
Nice information. Why the ratio of N is 10 % even used in the form of NO3 ion or NH4+ ion?
I’d like to know this too. Additionally some fertilizers have three forms of Nitrogen ( urea )
Thank you
Have you heard of REV? It is a company promoting an Omni approved liquid fertilizer. Wanted to know if it is a legitimate claim to the product.
Interesting video (I enjoy the info you provide on your channel). I decided to ask Chat-GPT and it initially told me that the N-P-K were indeed weight percentages of those atoms. When I pressed for more, it responded as below. Now, Chat-GPT is often wrong, but I wonder what you think of this possible explanation?
I asked it: "Does the P actually represent phosphorus or phosphorus pentoxide? And does the potassium represent potassium or potash?"
Chat-GPT: "The P in the N-P-K ratio of fertilizers does indeed represent phosphorus, not phosphorus pentoxide. Similarly, the K represents potassium, not potash.
Phosphorus is a key nutrient for plant growth, particularly in terms of root development, flowering, and fruiting. In fertilizer labels, phosphorus is typically listed as P2O5 (phosphorus pentoxide) because historically, phosphorus was extracted from phosphate rock, which contains phosphorus in the form of phosphorus pentoxide. However, the P2O5 value is converted to its elemental form of phosphorus for the N-P-K ratio calculation. For example, a fertilizer with a label of 10-10-10 contains 10% elemental phosphorus.
Potassium, similarly, is an essential nutrient for plant growth, contributing to overall plant health, disease resistance, and stress tolerance. It is typically listed as K2O (potassium oxide) on fertilizer labels because it was historically extracted from potassium salts, which contain potassium in the form of potassium oxide. The K2O value is converted to its elemental form of potassium for the N-P-K ratio calculation."
What's your thoughts of supersoilfertilizar
So I just watched one of your video's saying never to buy 10-10-10 because we need 3-1-2 -- and based on this video, it sounds like 10-10-10 is not far off of that (if it's 10 - 4.4 - 8.3). Am I missing something?
Makes perfect sense.
Why do we not convert the three different forms of Nitrogen % into the elemental form of N, like we do for P and K ?
BUT, arn't recommended application rates based upon the SAME understanding of the compounds proportions?
They are.
I’m going to argue with the people at the garden center. Most of them are clueless.
build your soil with natural amendments and compost and you can forget about the chemistry. Cheers!
Not True. For example too much manure will make your soil toxic with too much phosphorus.
ruclips.net/video/lo7Smm2-mDI/видео.html
Yeah, that's like shooting fish in a barrel. You'll be sure to get a few but then things won't be looking so well!
I choose to compost the hot stuff like chicken manure before putting it in the ground. Have a process that works and stick to it. You'll have lush plants. @@Gardenfundamentals1
So what is the rest of the bag? 10-10-10 adds to be 30 percent. What about the rest or 70%? is it soil?
Carrier material.
70% of trash 😢😢😢
Inert material
Most states took the Middle ingredient out of Turf Fertilizer, that’s what keeps grass roots healthy. Now have bare spots, as the grass dies. County can Cite me for this, luckily so far they can’t fine me.
You have an error at around 4:20. You were talking about potassium, but said "if you drop phosphorus into water it would burn". Phosphorus is stored in water to keep it from burning. But if potassium is dropped in water, it will release hydrogen from the water, combine with the freed oxygen to generate enough heat to ignite the hydrogen. FYI.
Otherwise, you did make a very good point about fertilized numbers. Thanks.
Correct - I misspoke.
@@Gardenfundamentals1 No worries. It happens. And the sneaky things get past editing sometimes.
It's not that those publications don't know what they are doing, but that they use a convention that we need to be aware of. We aren't the only ones who have a clue.
Ik In ag soil test are calculated with the pounds adjust in there reconditions. I don’t think any of your examples are wrong they are just assuming ppl reading are familiar with this
Now I get it, I was reading a label and something didn't figure. Or so I thought. The label said what he said if you really studied it. Probably why I was having a hard time getting to what the numbers on the label said it was.
Fertilizer recommendations are often based on the industry standard which is K2O and P2O5 molecules you're referencing, not actual element measurements. If people follow your recommendation, they may over apply.
you're saying not to use a balanced fertilizer but the video is about how 10-10-10 is more like 10-4.4-8 so isn't this close to what you want? assuming your soil needs all 3 or your soil tests show you don't already have too much of one and not the other? can you please clarify or do a video explaining what percents you do want, assuming your soil tests don't show a deficiency or surplus of one or the other
The video does not say "10-10-10 is more like 10-4.4-8". A 10-10-10 is always a 10-10-10 or if you just want the reduced ratio it is 1-1-1. The 4.4 and 8 values should not be used in a ratio.
If the soil test does not show a deficiency - you should not be fertilizing.
If the soil test shows a deficiency you should add only what is needed and the soil test will tell you that.
What form of nitrogen is in 10-10-10 typically. If it’s in a nitrate form wouldn’t the first number be the ratio of the atomic weight of the Nitrogen and Oxygen or the other molecule components? Nitrogen doesn’t exist in solid form but as a gas as N2.
Nitrate nitrogen is an oxidizer and it needs careful storage as it is a fire hazard.
Ammonium sulphate and a variety of urea products are common.
Other nitrogen sources might be blood, feather and seed meals.
The seed meals are the left overs after oil is removed from seeds like canola or soy.
I never assumed that these proportions reflected pure elements. Obviously it's the ratio of bioavailable compounds. That's why many bags clarify the content with with "as ammonia sulfate" or whatever chemical composite this element comes in. You are overthinking it. Looks almost like a clickbait to me.
I was told it’s the best for fruit trees ??? Is that true ???
I am not sure this is right. 10-10-10 means 10% of each. The rest 70% consist of the other substances mainly oxygen?
But doesnt the "balanced" formula come pretty close to a NPK ratio of 3:1:2?
No - If we are using the term balanced the way most gardeners use it, the formula has a ratio of 1-1-1.
👍👍👍.Thanks
Thanks for the video. I really like what you present. At 2:42 you talk about N2. But it is made up of two nitrogen atoms, not two molecules. At 4:24 you don't want to talk about phosphorus, you want to talk about potassium.
Hello question, what PH helps keep weeds away? 👍👍
1
Nice, but that would also keep my vegetables away. 😂
These screenshots says a lot about education system.
I have no idea 10 whats exactly but it doesnt say percent or pounds so its not. Its 10 thingys.
just grabbed my mono phosphor fertilizer and its 0 - 17 - 0 but it contains 16,6% p2 o5
I also do not understand why Nitrogen is correct (10%) in spite of being in a molecule normally N03. (That is 10 kg N and >30 kg O because O is heavier than N )
10% is the percentage in the bag of Nitrogen. Divide bag weight by 10% to get actual weight of nitrogen. 10% of a 35 lb bag = 3.5 lds of PRODUCT containning 10% Nitrogen. A lawn needing 1 lb per 1000 sq feet a month needs 3.5 lbs of product per 1000 sq foot a month. Thanks for the explanation on the rest of the mix and how the other numbers are misleading.
if fertilizer is only made up of 22.7% of NPK what is the the other 77.3%?
filler - something that adds bulk but no real value.
I’m a retired chemist who formulated fertilizers and provided technical advice for labels. The other 77.3% is oxygen, and other part of the fertilizer salt. For instance potassium chloride, potassium sulfate, ammonium sulfate contain sizable amounts of Sulfur or Chloride. Usually they don’t use fillers in soluble fertilizers because soluble fillers can be as expensive as the nutrients.
N2 is a gas at room temperature - so wouldn't nitrogen in fertilizer be stored as nitrate/ite N03-, urea CO(NH2)2, and/or ammonia NH3. Wouldn't that affect the actual weight of nitrogen in the fertilizer?
I don't understand the question. The weight of the fertilizer ingredients does depend on the form used in the fertilizer.
All usable nitrogen, including proteins in organic fertilizers, has been converted to the equivalence of N for comparison. Therefore, the form of nitrogen does not affect the actual weight of nitrogen in the fertilizer.
Soil test result recommendations are written to the manufacturer’s labeling.
This is pi$$ on a fire hydrant
4:55 - if you understand chemistry & chemical formulas, the punchline of the background knowledge comes in here. Very interesting!
As someone working off of a soil test on my own land this just helped me out. In cases of deficiencies, this surely leads people to think their fertilizer regimen isn't working when in reality they may not be applying enough, outside of Nitrogen.
We write what we do for simplicity. And for over 100 years it has worked perfectly. Doing exactly what we ask of it. Why do we write it the way we do? Simple really. I will leave that response out so snowflakes don't get pissy. Here is all people need to know. We provide the ratio of utilizable nutrients per weight of the bag. Nothing more. Nothing nefarious.
I will never get the time spent watching this back.
Your website has a 503 error and cant be seen
Had a problem last week - should all be working now.
@@Gardenfundamentals1 It's work now. Thank you lots of good information to explore
Well tell us??
Great video but still don't know how much to use.
In gardens you add what is missing from the soil. If you don't know what is missing you won't know what to add, so add nothing. In containers use a 3-1-2 ratio.
I hate when marketing folks mess up with numbers despite what chemist and science are telling them.
A sack of potassium nitrate is 100% potassium nitrate. Its fertilizer rating is 13-0-46. Please explain.
Explain what? It has potassium and nitrogen in it.
Robert's a sasquatch and myth buster.
🤣
🤣
he just pwned all the fertiliser companies and websites.
It's still all the same in practice, just throw a little on and go
Interesting but hard to watch because of all the glitches in the video
Aren’t you supposed to get a soil test done and then add what is needed? 🤔
That is better than just using 10-10-10 or any fertilizer. But even better is not to fertilize and see if stuff grows. If it grows you don't need to add any fertilizer.
I’ve been using 10-10-10 at the start of the season to wake up my tttf and my lawn looks awesome. Don’t care what you think you know. When someone says everyone else is wrong and they are right I tend not to believe a word they say
🇪🇬🤝🥭
Trust the SCIENCE!
Organic agriculture usually disdains the NPK numbers because they are a tool developed for chemical farming and agribusiness. Focus on soil tests suffers from the same disconnect. This all goes back to von Liebig and his materialist, reductionist paradigm. If you adopt a wholistic and balance-based paradigm, the whole discussion is moot.
So spit it out already !
I had a nitrogen back up one time in my Willy didn’t endwell
so what you just said is that a 2-2-2 is actually a 0-0-0
Now I am very confused!
Get ur county agent!!
Id be careful sir. I beleve in some countries its %P...
So a 101010 is a 10-4.4-8.3 Thats probably ok for Florida.
No. A 10-10-10 is just a 10-10-10. But it is not 10% P and 10%K
Ok then tell me why walmarts 10 10 10 is different then a local gardeners 10 10 10?
so basically what your saying is that the fertilizer we buy has what our plants need , because if they had the actual element , it would be bad , thanks for being over pedantic about it
While you’re correct, you’re splitting hairs and making it more complicated for the average user. When you get soil test results they are listed in units of P2O5 and K2O that are needed, thus why the fertilizer bags list them as such. The average person can use those numbers to easily apply what the soil test recommends. Don’t make it more complicated just to get views.
Thanks for clarifying this!
100
Not too complicated 😅
4 percent vs 10 percent is not splitting hairs, I’m my mind. That’s a huge difference and must be accounted for in your fertilization routine.
Well that statement from CIL doesn't seem inaccurate they didn't specifically say they were talking about percentages in terms of weight for a 10-10-10.....oh wait yeah still inaccurate because then you would only get 30% in total and nobody has ever purchased 30% of a bag of anything at least not the way that works.... Sorry I realized while I was typing my gotcha comment that I'm just an idiot but the comments still gives you some good for the numbers and all that the algorithm I think they call it viewer interaction or something like that or viewer engagement
Unfortunately, most people don’t like chemistry and as soon as they passed (or failed) the exam, they wiped it out of their brains. The media, particular pepper journalists, are hilarious as they mansplain science to us, usually getting it 180° from the correct answer.