Richard

Among other things, I have spent the last year studying optimal formulations for growing tomatoes in all types of environments. It has been very rewarding from both an analytic and personal standpoint. The results are applicable to nearly all annually grown herbaceous fruiting plants, including members of Solanaceae (tomatoes, peppers, potatoes, eggplants, ...), Cucurbitoids (melons, squash, cucumbers, ...), Beans (kidney bean, lima bean, ...); but not other legumes such as peas -- or for that matter cannabis.

Key point #1: There are presently no single-bottle, single-bag, or single-box solutions. Please don't ask where to buy it.

Many commercial growers have known some or all the formula for decades and if you wish you can go read about it at university agriculture extension web sites, and also at web sites of some commercial suppliers. The "mix" is not available in a single bag for historically practical reasons -- one of which is the difference in mineral content among farmers' water supplies. This is changing due to the increased use and lower prices of reverse-osmosis water filtering systems.

First let's look at the primary nutrients N, P, K. There are several scenarios:
1. Soil grown, determinate types, organic: 4-4-7
2. Soil grown, indeterminate types over a long season, organic: 4-2-7
3. Soil grown, determinate types, water-soluble: 11-12-21
4. Soil grown, indeterminate types, water-soluble: 11-6-21
5. Hydroponic, determinate types, liquid: 4-4-7
6. Hydroponic, determinate types, water-soluble: 11-12-21

Key point #2: All of these are applied during growth phases 1, 2, and 3 so that the concentration of K (potash) is respectively 150ppm, 200ppm, and 250ppm.

Now because my interest in obtaining a tomato food that is suitable for consumers and also acceptable by those interested in organic gardening principles, I am going to focus here on the lower concentration scenario. Why lower? Because it is not possible to have a higher concentration of nitrogen and satisfy USDA certified-organic requirements. I would also like a liquid solution so that the efficiency of fertilizer injection can be employed, both in soil-based and hydroponic applications.

Ok, so having stated all my caveats () here is the scenario for soil-grown:
4% N
4% P
7% K
0.43% S
0.85% Mg
1.70% Ca
0.1% Fe
0.005% Cu
0.02% Mn
0.01% Zn
0.02% B
0.0015% Co
0.0015% Mo
0.4% Alfalfa Extract
0.25% Barley Extract
0.4% Kelp Extract
0.4% Sugars
1.2% Humic Acid

For hydroponics, extra Sul-Cal-Mag is needed. The changes are:
0.9% S
1.75% Mg
3.50% Ca

So in future posts I will explore what it will take to get this mixture from available materials and what it will take to get it produced on a commercial scale.

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fmu65

That would be so appreciated! All the bagged "tomato" foods, as we have discussed on the citrus forum, are not in balance. So frustrating!

nannerfunboi

so true richard ..that "one bag"."one fertilizer" gives what
our tomatoes need to do their best..
i grow my tomatoes in the ground..full sun.all day..
my vegy garden has rabbit manure,straw,and leaves spaded in
every fall..
for me..and im so still learning.. i dig in 1/4 cup epsom salt and
kelp meal into holes
this yr..im going to add alfalfa meal to the holes..ive read its a great
growth hormone source..
then i use mix of my own rabbit manure tea,and a liquid fertilizer
its low on #s.. 6:4:4 i figure the rabbit manure gives an extra boost
on the potash..
i also add every other yr.. agriculture limestone.. helps prevent
blossom end rot..
im also going to try dry molasses this yr too..
ive read good things on that..
last yr was a crappy yr here .. tomatoes were..just ok on production..
but everyone here (utah) did lousy..so.. wasnt just me.. so
i like to tell myself..
hope many others post their experiments..
really grateful to ya richard for your diligence in horticulture !!!!

Richard

I'm sure that many gardeners here have grown great tomatoes outdoors. Basically if you follow good gardening practices, have a soil mixture containing both minerals and organics, grow it in full sun, water adequately, and provide some source of nutrients -- whamo! You get a good crop of delicious tomatoes. So if you are happy with your tomatoes I'm not saying you should do anything differently.

The hydroponic situation is not quite that easy because everything must be provided to the plant. Our knowledge of tomato requirements along with many other vegetables has been extended by studies for production-oriented hydroponics. One very important principle is that it is not enough to have all the nutrients present for optimal performance: they need to be within certain ratios of each other.

Key point: An over- or under-abundance of one ingredient can limit a plant's utilization of another. For optimal crop performance, inorganic and organic compounds need to be present in certain ratios with each other. This is why the formula I'm presenting is a recipe instead of a list of ingredients.

Here are several examples of conflicts among nutrient compounds:

• Excess Aluminum depresses Magnesium, Calcium, Zinc, and Manganese
• Excess Alfalfa Extract over-regulates plant growth unless sufficient Barley extract is present
• Excess Barley Extract depresses Alfalfa Extract
• Excess Cadmium depresses Copper
• Excess Calcium depresses Manganese, Magnesium, and Phosphorus
• Excess Cobalt depresses Iron
• Excess Copper depresses Iron, Zinc, and Phosphorus
• Excess Iron depresses Potassium, Phosphorus, and Copper
• Excess Magnesium depresses Phosphorus and Calcium
• Excess Manganese depresses Iron, Phosphorus, Potassium, and Magnesium
• Excess Phosphorus depresses Zinc, Iron, Calcium, and Magnesium
• Excess Potassium depresses Sodium, Iron, and Manganese
• Excess Sodium depresses Potassium
• Excess Zinc depresses Iron, Copper, Phosphorus, and Cadmium

The first item on this list (effects of Aluminum) is why I am not a fan of Azomite.

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harveyc

Somewhere around here I might still have slides from a hydroponic nutrient deficiency experiment I did at Cal Poly about 35 years ago. My partner (co-experimenter) and I mixed our nutrient solutions using distilled water, etc. and had some useful results. I'm sure information has advanced over the years since then and my memory of things the particulars is pretty limited. The only thing I remember is that iron and nitrogen deficiencies appeared similar.

Edit: Oh, and I remember my roommates appreciated fresh greenhouse tomatoes in the winter!

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Richard

Next I would like to discuss the mixing of fertilizers. To keep it simple, I'll start with just N-P-K. As I've mentioned before, these numbers are percentages by weight. If you mix two fertilizers, the numbers do not add, but instead average by weight.

Example #1: if you add 1-lb of 10-0-0 with 1-lb of 0-10-0 the result is 2-lbs of 5-5-0.

Example #2: if you add 4-lbs of 10-0-0 with 1-lb of 0-10-0 the result is 5-lbs of 8-2-0.

Here is a small Excel spreadsheet that shows an calculation for example #2: N-P-K_Mix_1.xls.

In my next post, I'll show how to mix some standard plant nutrients to obtain an N-P-K with ratios 4:4:7.

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fmu65

Is there a good resource or equation I may use to determine the amount of potash supplement to use? For my lemons, I purchased the only potash supplement my store has, which is 0-0-60. At your recommendation, I want to add some to balance out the nitrogen and phosphate in the proportions you had recommended and also for my tomato plants. I also have a test kit so I will be able to check existing levels (at least in the ballpark) to know where I am starting from. Thanks for your help!

By the way, as an answer to your comment from the other post, I have been surprised how many people either don't measure fertilizer or think "more is better" so that is why the low percentage fertilizers are preferred to keep people from burning the roots of their plants.

Richard

Take it back. That is muriate of potash which is high in chlorine. It is really a pool chemical that some manufacturers also market as a fertilizer.

Two common elements you never want to see in more than trace amounts (less than 0.1%) in a fertilizer: Sodium and Chlorine.

Yes, and since the needs of citrus are different from those of tomatoes, lets talk about it in one of the citrus threads. I will also want to know what you are using for a source of nitrogen.

Note. I have added a link to an excel spreadsheet in my previous post.

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fmu65

Thank you, I will! I just did a little reading up on it, and the product labelling is extremely misleading. It does say muriate of potash, but it gives a chemical symbol of K2O. Wow, and this is from Espoma, who is supposed to be a decent company. I need to get out the chem textbooks and brush up.

Richard

For people who don't want to brush up on chemistry, that's ok -- overall in this thread it won't be necessary!

By law the potash content must be listed as K2O equivalent -- so the label is correct. It would be nice if also somewhere on the bag it gave percentage by weight of Chlorine.

For example, there is an inorganic supplement I use in the spring called monopotassium phosphite which has the chemical formula KH2PO4. On the label however, the potassium content is listed as 20% K2O equivalent.

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sunfish

I hope this is okay I've got 300lb. I need to use up'

Richard

The topic has been "how to mix natural sources of plant nutrients for tomatoes?". The answer is: there are many ways to do it, but ultimately the goal is to have the N, P, and K in certain ratios to each other.

Since we are also having this discussion with regard to citrus, I have created an excel spreadsheet that might help you make decisions on fertilizer mixes for tomatoes, citrus, and other fruiting plants. Well see

Here's a link to the spreadsheet: N-P-K_Mix_Analysis_v02.xls

P.S. great potash supplement you've got there Tony!

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Richard

Some folks asked for dosage information in the spreadsheet, so added that and called it: N-P-K_Mix_Analysis_v02.xls.

As an example for determinant tomatoes, you could mix
1 lb Blood Meal (steer)
0.875 lbs Bone Meal
0.49 lbs Potassium Sulfate or 1.1 lbs Sul-Po-Mag
For a plant outdoors in a 15 gallon container the dosage is about 0.1 lbs per month.

Keep in mind that this is just for the primary nutrients. In follow-up posts I'll start discussing appropriate ratios of minors, micros, and hormones for tomatoes and other fruiting annuals.

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stefano79

try go read more about tomato crop guide here, maeby it will help some of you : Tomato Fertilizer - Haifa Group