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oxboy555

If the optimal fert ratio is 3-1-2...

oxboy555
9 years ago

....for all plants according to science, how come so few fertilizers incorporate this ratio?

Are fert producers just slow to react? Or do they all know it but just disregard so they can feed marketing hype?

Comments (15)

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    It may not be exactly optimal for every plant, but it's dead center in the not too wide range of nutrients used by all plants. Here's the comparative chart with fertilizer usage listed in comparison to 100 parts of N.I gave Nitrogen, because it is the largest nutrient component, the value of 100. Other nutrients are listed as a weight percentage of N.
    N 100
    P 13-19 (16) 1/6
    K 45-80 (62) 3/5
    S 6-9 (8) 1/12
    Mg 5-15 (10) 1/10
    Ca 5-15 (10) 1/10
    Fe 0.7
    Mn 0.4
    B(oron) 0.2
    Zn 0.06
    Cu 0.03
    Cl 0.03
    M(olybden) 0.003

    To read the chart: P - plants use 13-19 parts of P or an average of about 16 parts for every 100 parts of N, or 6 times more N than P. Plants use about 45-80 parts of K or an average of about 62 parts for every 100 parts of N, or about 3/5 as much K as N, and so on.

    Fertilizer companies produce so many fertilizers because of the market created for them by uninformed growers. As long as 1 manufacturer is getting a slice of the market pie, all the other producers will follow suit, giving you what you want (after reading the advertising hype) but not necessarily what you need. Fertilizers in the 3:1:2 ratio labeled as "All-Purpose" (like MG, Scott's, Jack's 24-8-16)have been around as long as I can remember and probably long before.

    Al

  • drew51 SE MI Z5b/6a
    9 years ago

    Some of it is what is used. For example organic ferts...Cottonseed meal cannot change it's ratio. Another difference too is that most organics you use all of it. It doesn't leach out. Also 3-1-2 is far from universal each plant group has different needs. Pointed out time and again by various university studies and recommendations. Plus if you use soluble best use 9-3-6 as more than half goes right out of the pot.
    To give you another example, of why this is not universal. We have plants animals and fungi. All animals are certainly not the same, and the suggestion that plants are is ridiculous. Dogs do not need vitamin C, well they do, but they make it themselves. I would highly suggest not to feed anything with fruit in it to dogs. Yet many products do have fruit, Dogs and people are fairly close, both mammals, yet our nutritional needs vary greatly, same with plants. Even closely related plants.
    Legumes fix nitrogen, obviously your premise is incorrect for legumes. Blueberries have a hard time metabolizing nitrates, levels can become toxic. Foliage Pro can kill blueberries. These are not exceptions to the rule, these are the rules. Each plant group is different, thus now you understand the various ratios offered, mostly for a certain plant group. Based on science.
    The idea that they all use the food the same way tells us little. Most animals also digest food the same way, the basic mechanisms are similar, and the idea all plants have the same need are based on these types of basic metabolism models. Which is extremely misleading. It's just not that simple. How you feed plants that digest meat matters, and again does not fit this model.
    The reason we have so many different fertilizers is because we have so many different kind of plants, each with it's own needs, and methods of adapting that matter when feeding.

  • oxboy555
    Original Author
    9 years ago

    Al, do you grow roses in the ground? If so, I'm curious about your fertilization schedule.

  • oxboy555
    Original Author
    9 years ago

    Drew, what would be your feeding routine for roses in the ground?

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    Drew - any fertilizer can kill blueberries. I agree that on blueberries, FP is not a good choice, and I've said that many dozens of times. BTW - if there are a few plants here & there that don't tolerate Nitrate forms of N well, they ARE the exceptions, and singling out an exception and presenting it as the norm is intentionally misleading, but you're no stranger to that - just so you get that axe ground.

    What IS ridiculous is comparing plants to animals. They are Very different organisms.

    Yes, you can learn the very specific needs of every plant and buy dozens of different fertilizers that probably won't come any closer to exactly what a plant needs than FP for 85% of the plants we grow. No one ever said it is or should be a one size fits all, that's you talking and talking and talking. The fact is, hundreds and hundreds of growers here at GW and elsewhere use FP 9-3-6 combined with 9-3-6 and enjoy better results than they've ever had before. My wish isn't that everyone does things MY WAY, I simply try to get people to a sound platform at the early stages of their growing so they have a sound foundation to build on. Occasionally I run into someone like you who is more interested in making me look stupid than their own credibility. I've seen you ridiculously twist things over and over again, and say things I know you know aren't accurate, all for no reason other than you don't like the things I say/do.

    OB - I don't grow roses, but I have a couple of large gardens with lots of bones. No fertilizer is the right fertilizer for plants in the ground unless its basis is a soil test. There is no way to tell what your plants need more of, or how to reduce availability of a particular nutrient w/o testing the soil.

    Al

  • Ernie
    9 years ago

    Here's an old thread that I found very informative...

    The Uselessness of High P Fertilizers

    As Al noted above, it's about marketing, marketing, marketing.

  • oxboy555
    Original Author
    9 years ago

    A related question I have is:

    We see the nitrogen number on N-P-K labels as anywhere from 1 or 2 all the way up to 25+. Obviously 1 is low and 25 is root-scorching high. But how do you know if a particular plant NEEDS a 2 or a 5 rating or a 9 like Foliage Pro per application?

    Our Dynamite CRF is 15. Why? Why not 7 or 11? How did they arrive at 15?

    Is there a sweet spot of say the 4-9 range that just 'feels' right for most plants?

    Curious...

  • nil13
    9 years ago

    "We see the nitrogen number on N-P-K labels as anywhere from 1 or 2 all the way up to 25+. Obviously 1 is low and 25 is root-scorching high. But how do you know if a particular plant NEEDS a 2 or a 5 rating or a 9 like Foliage Pro per application?"

    No, no, no.
    25 is not root scorching high. Whether the number is 1 or 100 has little relevance when it comes to fertilizer burn. What matters is the application rate used. Something with 25 N just means that you have to use less of it to mix up a batch of fertilizer with say 100ppm of Nitrogen than you would if it were 5 N. So if you like buying, storing, and hauling a bunch of fertilizer use the 1. If you would rather buy, store, and haul fertilizer less frequently use the 25.

    Stop just dumping 1 tsp/gal of whatever fertilizer you are using people and learn how to calculate proper concentrations. It's easy. 100mg/L = 100ppm. Now that assumes a 100 percent concentration that we don't get in our dry ferts so we have to adjust for that. If the dry fertilizer is 25N that means 25% nitrogen. So... 100mg x .25/ 1L = 25ppm

  • nil13
    9 years ago

    "Another difference too is that most organics you use all of it. It doesn't leach out."

    This is not accurate. Organic fertilizers need to become available to the plants before they can be used. Once the nutrients are available to plants, they also have the potential to leach out of the container. Some organic ferts like bloodmeal are quite water soluble and can easily leach out. Others like bonemeal are quite water insoluble and thus less susceptible to leaching. But once that water insoluble nutrient has been made available it can leach as well if it doesn't get used up before the water carries it away.

  • oxboy555
    Original Author
    9 years ago

    Sorry, I was talking about mainly in-ground, not container. Should've clarified or gone to another forum.

    Still though...I'm still majorly lost. I guess I need a workshop or something.

    My question is more about the N nutrient need of plants, not burn avoidance. If I'm standing here looking at a potted geranium, and I have both 9-3-6 and 30-10-20 liquid ferts in front of me, how do I know which is best for the plant??

  • nil13
    9 years ago

    Without being able to look at the ingredient list to see where the nutes come from, they are identical in composition. One is just more concentrated than the other.

    Now one might have more urea and the other more nitrate and that can make a difference depending on what you are fertilizing. However if we are talking about in ground that is most likely nothing to worry about.

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    The numbers like 9-3-6, 12-4-8 and 24-8-15 are the % by weight of N, P, and K respectively in the product. Those numbers are actually not too important, other than as a means by which you can determine the fertilizers RATIO, which is much more important and in this case would be 3:1:2. Note that the fertilizers %s are written with dashes between the numbers and the ratios with colons. Fertilizers like 20-20-20, 14-14-14, and 10-10-10 are all 1:1:1 ratios.

    Miracle grow makes 24-8-16 and 12-4-8. Both are 3:1:2 ratios. The instructions on the label will direct you to use half as much 24-8-16 as 12-4-8 (by weight), so in the end, you will be making a solution of the same strength. If you were comparing FP 9-3-6 to the 12-4-8, you'll find you're using about 1/3 more 9-3-6 as you would 12-4-8, and 2.75 more 9-3-6 as 24-8-16. IOW - when you're done mixing, if you followed the directions the solution strength will be very close for all soluble fertilizers.

    For granular slow release fertilizers (not controlled release), you would be directed on the package to use 50% more 10-10-10 per given volume as you would be directed to use 15-15-15; so again, the rate at which you fertilize would be exactly the same.

    It's not the numbers 9-3-6 that determines how close to being in the sweet spot FP is, it's the 3:1:2 ratio, and any other fertilizer with a 3:1:2 ratio would be its equal if all you consider is NPK content. I like FP because it supplies all the nutrients plants need from the soil at a ratio that hits dead in the center of the average of what all plants use. Plus, it doesn't get it's N from urea, which is a definite plus unless you're growing blueberries, in which case something with urea is desirable.

    Most CRFs supply individual nutrients somewhere in the 6-20% range. I don't know why, but suspect that with the weight of the coating and even using nutrients as concentrated as they can make them, it might be difficult to make the actual weight of all nutrients combined higher than 50-60% of the total weight of the product. Just a guess.

    Al

  • tapla (mid-Michigan, USDA z5b-6a)
    9 years ago

    If I'm standing here looking at a potted geranium, and I have both 9-3-6 and 30-10-20 liquid ferts in front of me, how do I know which is best for the plant??

    If you limit the focus to the fertilizers N or NPK content, the 30-10-10 has about 3.33X more of each nutrient, but since you'll be directed to use about 3.33X more 9-3-6 than 30-10-20, the solution strength you're applying will be the same. If you want to determine which 3:1:2 ratio is better for your plants, you'll need to look at things OTHER than NKP %s or ratios, because those 2 aspects offer no significant difference in the end.

    What seals the deal for me is the fact that FP has ALL the essential nutrients plants normally take from the soil, in soluble form. There are precious few fertilizers that can make that claim. I also like the fact that FP doesn't get its N from urea, which promotes coarser growth - longer internodes and large leaves.

    Following?

    Al

  • nil13
    9 years ago

    I thought the longer internode length was found to be from excessive P not from urea.

  • oxboy555
    Original Author
    9 years ago

    I'm getting it. Thanks for the info, guys.

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