what is the soil like? if you have added compost/OM/ anything in significant amounts, you only need 10/0/0. Excess P has a number of bad consequences, most notably blocking iron absorption.

You won't find any studies saying that 10-10-10 is bad. But the belief that such fertilizers are "balanced" because the numbers are the same is just nuts. Plants need all of those constituents, and if your soil already has plenty of one, 10-10-10 won't hurt, unless you're using a tremendous amount of it. You can take a "balanced" vitamin pill every day that your body really doesn't need because you get all you need in food. Won't hurt you. If what your plants need is N for better foliage, 10-10-10 is not the optimal choice, but won't do any harm, and will help some. For half-decent soil, fertilizer is an "amendment" to the soil, not a defining property that makes it good or bad.

10-10-10 is fairly potent, and possibly water soluble chemical fertilizer, which can burn your plants if used incorrectly (which isn't really all that difficult to do.) What exactly is this fertilizer?

Also taking too much of a vitamin you don't need can hurt you.

I would prefer the 10 for N, to be smaller than the other two. And K to be higher than both N and P. I use FoxFarm Big Bloom (0.01-0.3-0.7) [organic] and I think it's a pretty good one.

foxfarm big bloom $44.00 a gallon vs a 50# bag of 13-13-13 for $20.00. I will stick with what makes more economic sense.

Nope, if I take five One-a-Day vitamin tablets every day, it sure isn't going to hurt me. If I take a hundred, I'd probably get an upset stomach.

Also, pretty much any decent fertilizer can burn your plants if you use too much of it. So that can't be used to criticize 10-10-10. Fertilizers with very low nutrient numbers are certainly highly benign, but they're also pretty useless.

In the absence of a soil test, there is nothing wrong with 10-10-10.

Non-water soluble fertilizers can't burn your plants AFAIK. It is when salts dissolve in water that your plants roots get burned. There is a huge difference between routine use of slow release organic fertilizer, which you can more freely use, and chemical fertilizer which needs to be used properly and carefully. These are apples and oranges to me, and the same advice can't be given for both IMHO. We are talking about a hypothetical 'using 10:10:10' with no other information whatsoever and IMHO it is not sufficient.

And if you take a hundred vitamin tablets (which would be a more apt comparison to 10:10:10 fertilizer as it is potent and far more nutrients than your plants need in a single day), you absolutely could do serious harm to yourself. There are many vitamins/minerals that are toxic when use in excess, and some vitamins/minerals when used in excess can block other vitamins/minerals from being absorbed/utilized - especially when in pure chemical form.... and the same is true of plants.

The organic vs. synthetic issues aside, much of the negative press about both 10-10-10 and 13-13-13 is only directed at the middle number, the phosphorous, because of all the phos run-off problems that have developed over the last decade. Algae blooms, ground water, lake and river contamination, fish kills, etc. caused by all the excess phosphorous used in fertilizers that isn't really needed or used by the plants.

Low phos soils are quite rare and both 10-0-10 and 13-0-13 are both now available if you want to use granular fertilizers, and many do with no problems whatsoever. But many also tend to abuse their use because under-informed gardeners tend to think "if a little is good, a lot is even better" when just the opposite is true and "if I put a lot of this in now I won't have to feed them again later", also untrue.

Dave

I first learned to garden with 10-10-10, and still carry the amounts to use around in my head though I use a regionally-produced organic product that's 5-4-3. Yesterday while setting out fall cabbage, which needs fertilizer in my climate and soil, I realized that I target the location of the fertilizer to the root zone of the species more and more.

Other than possibly being a waste of money, can one conclude that the right amount of 10-10-10 does no harm to any plant?

<Other than possibly being a waste of money, can one conclude that the right amount of 10-10-10 does no harm to any plant?>

Harm to the plant? Some as there are nutrient toxicity symptoms that can be displayed by plants. But they are usually associated with either the binding properties of the various nutrients (eg. excess N can bind and prevent the absorption of calcium or interfere with the plant's ability to absorb phosphorous) or with the metals and micronutrient effects.

Harm to the environment from run-off of phosphorus and excess nitrogen is something else. So yes, there are consequences other than a waste of money. And this begs the question of what is the "right amount"? Does every garden need the same amount of N-P-K? No. There is no way to know the right amount for your garden without a professional soil test. Without that base of knowledge any fertilizer added could easily be the "wrong amount".

Depending on where you live browse through the local news on run-off contamination problems in your area. It has become a serious problem for most of the larger lakes and rivers throughout the country. Wisconsin, the Great Lake states, Ohio, the Mississippi, Colorado, and Missouri river bound states, the Everglades and Gulf of Mexico, Florida, are often in the news with this issue but even smaller lakes and streams often test with overly high levels.

Dave

I know for a fact that my property has no "run-off" although the water company taxes me for it when I water my gardens. However, I specified that I am using the correct amount of 10-10-10 if not using a lower concentration than what in the directions. I question that just by the mere fact that it is 10-10-10, can that hurt any plants?

Any one can put too much of anything on any plant enough to do damage. This is not what I am talking about.

My point is that I hear and read about the horrors of using 10-10-10 and that "no plant wants 10-10-10" yet they never suggest anything except anecdotes.

"But they are usually associated with either the binding properties of
the various nutrients (eg. excess N can bind and prevent the absorption
of calcium or interfere with the plant's ability to absorb phosphorous)
or with the metals and micronutrient effects." as is with all other conditions in gardening but does 10-10-10 have a direct effect on this?

I am going to presume that, aside from over use, which can be done with any additive, that 10-10-10 is not the harbinger of horror that is professed by all these white-coat gardeners. It may not be the best fit, but it is not going to kill off my gardens.

<I question that just by the mere fact that it is 10-10-10, can that hurt any plants?>

If it is used in a vacuum, no. But you aren't doing that. Let's say for example that your native soil is already high in potassium and phosphorous (many are) and to that soil you add the bag label instructions amount of 10-10-10. You now have excessively high levels of both nutrients.

As a result you might begin to see the symptoms of zinc, boron, iron, and manganese deficiency. These may include interveinal chlorosis in various stages, netted veins, yellow to orange tinting in middle and older leaves, leaf roll and curl. leaves and stems may become brittle and split, distorted fruit, etc.

Is that a direct result of the 10-10-10? No. But it a secondary effect on the plants of applying the 10-10-10 to soil that doesn't need it.

If someone who has low phos and K in their native soil, which is rare, and they add the 10-10-10 then the only issues they may encounter that could be attributed to the 10-10-10 is overly lush green growth with minimal fruit production from the excess nitrogen in the mix.

So the problem IMO isn't the 10-10-10 per se. Aside from the run-off problems (and we all have those if only to ground water), the problem is the way in which it is used inappropriately and the claim by the manufacturer that the label applications rates are not only ideal but are the same for all soils. That's like saying we should all drive 55 mph anywhere in the country. The responsibility falls to the individual gardener to know the local speed limits and to know exactly what his soil and plants need and to apply only that amount rather than blindly follow the manufacturer's recommendations.

Dave

Face it, Em, everyone needs to expound their vast wisdom and knowledge (or is it half vast) and cannot seem to answer your question.

I have been using 10-10-10 now for many years and spread it twice a year at about 25% to 50% from the suggestion in the directions. Is it doing any damage? Not that I can see. Is it doing any good? Well, I rarely use any other fertilizer or additive and I am extremely happy with the results. My soil test returns that I have good soil content and recommends a light general fertilizer without really specifying and NPK rating.

In short, anything in moderation.
FWIK, 10-10-10 does not deserve the bad reputation.

"(which would be a more apt comparison to 10:10:10 fertilizer as it is
potent and far more nutrients than your plants need in a single day)"

10-10-10 does not determine how much nutrient a plant gets in a single day. That's governed by the application rate.

And yes, I'd get a bad stomach ache if I took a load of One-A-Day vitamins, But they are water soluble, and would pass relatively freely. Many vitamin supplements are 10x over the MDA, and people seem to survive those just fine. They don't seem to have a bad reputation. Overdosing on vitamins is certainly a bad idea for humans, but it's going to be hard to hurt yourself permanently by doing so.

Anyone who says that 10-10-10 is a harbinger of horror needs to be ignored.
Now, if you do dumb stuff with it, it can do bad things. If I do dumb stuff with 20-0-0 lawn fertilizer, it'll do bad things.

I have to wonder how people know what is the right amount of fertilizer. I moved in 2008, started a veg. garden again in 2009, first soil test showed 7ppm P (extremely low). Three years later, through organic matter only, it was 80 ppm (above optimal). It is surely above 100 now, even though I cut back to 40 bags of leaves a year for 23 beds since the 2012 soil test .

The same goes for K, although to a lesser extent. Yes it is mobile in soils, but never as mobile as nitrogen. My K is now well over 300 ppm (well above optimal). Really, there are almost no cases where you amend with abundant organic matter, and you are low in P or K, except maybe gravel soils. Keep in mind that compost is at the start a balanced food for plants, but then half the nitrogen is lost to the atmosphere. All the original P and K stay put, effectively creating an unbalanced food for plants.

Oh, what the voles must know. I have no idea why some of my beds are way better for some crops. There is definite variation between my 20 permanent beds that can't be explained through their history. Maybe gardeners who use a lot of fertilizers don't see it, because nitrogen is such a great equalizer, but when you run things lean it's a puzzler.

The meaning of the word "optimum" in soil tests is not entirely clear. For at least P and K, there is no concentration that is actually toxic to plants, though highly elevated levels of those can interfere with absorption of other nutrients. I know people who get soil tests showing P and K 4-5 times over "optimum", and they have no troubles at all. But there are people who bend over backwards to keep those levels within ten percent of "optimum". I am told that the relationship of at least P and K to plant health is very broad, in that although there are happy medians, plants can easily tolerate large differences from those "optimum" values. There is an "optimum" amount of water I should drink every day, and it's not going to hurt me a lot to drink half or twice that amount.

When we hear about garden problems with N, P, and K problems, we're almost always hearing about very large deficiencies.

If anyone has a reference to research on how large a swing from "optimum" values are tolerated well by plants, it would be nice to see it.

Just for information. Black Kow (composted cow manure) is 0.5-0.5-05 . which is the same ratio as 10-10-10. Basicly you have to use 20 bags of Black Kow to to get the same nutrients as 1 bag of 10-10-10. Not only is going to cost directly 10 times as much to use Black Kow, think of all the petoleum used in hauling that bulk to its destination. Most Compost will have somewhat similar numbers to Black Kow. Sometimes we get too penny wise and lb fooless. Certainly you can use a concentrated fertilizer to excess, but it is rare for anyone who is willing to take direction. There is a time and place for everything if we can put aside our prejudices and search for the more reasonable results for our resources.

Yes, that's what I was referring to earlier when I said that "some fertilizers with very low nutrient numbers are certainly highly benign, but they're also pretty useless." Now, that being said, composted manure offers a lot more than nutrients. I use such stuff less for nutrients and more for soil structure.

In my neck of the woods, the sale of 10-10-10 is prohibited, in fact its not possible to buy phosphorous on its own....it has to be accompanied by nitrogen with a ratio of at least 4-1. A balanced fertiliser here is considered something like 5-1-3 with a 'bloom buster' being around 3-1-4. The reason we are given is that research shows that plants use much more N than P and also the consequences of P on the environment. I'm not putting down 10-10-10, just repeating what the law makers say here.

Yes, the N/P needs vary from about 3/1 (fruiting plants like tomatoes) to 4/1(leafy plants like collards). Dan, I agree that optimum is a fuzzy concept. But why go above optimum? and spend money in doing it? and pollute the environment in the process?

Healthy plant leaves typically contain roughly from 2.5 to 3.5% nitrogen (on a dry weight basis), 0.2 to 0.35% phosphorus, and 1.5 to 3% potassium. We often don't apply them in these relative quantities, partially because uptake efficiency varies. Nitrogen, particularly, is easily lost from soil, and target plants absorb between 30 to 75% of applied nitrogen.

The ratio of your fertilizer is relatively unimportant. Apply as much nitrogen, phosphorus, and potassium as is needed. Find a fertilizer that fits your needs. This applies to organic and synthetic nutrient sources.