How to create my own organic fertilizer

[bombcat]

Hi everyone, I have been on this forum for a while now, finally made my first time posting, not sure if I post it in the correct forum. I have a question on making our own organic fertilizer, I have been using Dr Earth for a long time, and it is getting to be a bit expensive for a large garden (fruit trees, roses, veggie garden and etc...). I am wondering if any know if I am mixing them correctly to get the ration I need. We also started composting, but it is not generating enough for our garden.

I am looking to make a all purpose that means N-P-K is about the same, By using fish bone meal, alfalfa meal, Feather meal, Potash (KMag), Kelp meal and Cottonseed meal. It might sound a lot to purchase to begin with, but we are spending like $300+ on Dr Earth.... Mine as well mix my own.

What I have come up is their N-P-K value in 100 square feet.
2.5 lbs fish bone meal - 2-10-0
2.5lbs alfalfa meal - 3-2-2
2.5 lbs feather meal - 7-0-0
1 ozs potash (K-Mag) - 0-0-7
2.5 lbs kelp meal - 0.8-0.4-1.6
2.5 lbs cottonseed meal - 3-1-.5

So if I add all of the ingredients together, I should have N-P-K of around 13-13.4-12.1? Am I correct or am I adding it wrong?

Thank you in advance

[CharlieBear]

Organic "fertilizer" is a little more tricky than chemical. Those values you are using are estimates or average values. The actual product you obtain may not conform to those values unless they are lab certified at those values. The immediate usefulness of the nutrients in those organic supplements may not be released for quite a while, depending on where they got the produce, how it was stored, grown and under what conditions. Also you don't say where you got those values from are they on the bags of products you are planning to buy or out of some generalized garden reference. Also many organic fertilizers also contain other trace elements that chemical fertilizers don't, so will this mix also contain calcium, boron and so forth as well. If you had asked if my values are correct can I expect that this mixture will give me something roughly as good as 10-10-10 and with luck a little better than that, probably

[rainbowgardener]

Sorry, but you can't just add it like that. The numbers represent the percent by weight of the fertilizer that is N (or P or K).

So just looking at the N, you have 2.5 # fish meal that is 2% N, so 2.5x.02 = .05# N. 2.5# alfalfa meal that is 3% N =.075# N, 2.5# feather meal that is 7% N = .175# N, no N in the potash, 2.5 # kelp that is .008 N = .02# N, plus another .075# N from the cottonseed meal. So now you can add the amounts of N: .05 + .075 + .175 + .02 + .075 = .395 # of N. Multiply that by 16 and total you are adding 6.32 oz of pure N. But just as the amount of N got bigger, so did the amount of material. So to find what your N number (percentage of N) is you have to divide by the total weight of the combined material. That is 12.56 # or 200.96 oz. So 6.32 oz N divided by 200.96 total oz = .031 or an N number of 3.

Essentially you aren't adding, you are averaging the amount of N in each. The numbers are the concentration. By adding more materials, you didn't make it more concentrated, you just made it a bigger amount. So the total amount (oz) of N or whatever is larger, but the concentration isn't. Just in case this isn't clear, think of a bottle of beer that is 5% alcohol. If you pour two bottles of beer into a pitcher, it is still 5% alcohol. It did not suddenly become 10%. It is twice as much alcohol, but still the same concentration, because the alcohol and the water and other stuff all got bigger. To take in the twice as much alcohol, you would have to take in twice as much water with it.

Doing the math for the other nutrients, your combined mix comes out to be 3- 2.7 - 0.8.

That is fine. Compost often has NPK values of 1-1-1 or so. The thing about using compost and organic stuff is that you can use as much as you want. It is slow release and won't burn your plants.

[bombcat]

Thank you for a detailed reply. I was thinking something is not correct with the formula and you pointed to the error right away! I will try to redo the numbers.

I got those n-p-k values from the product i purchased. They listed their values. But like you said, it might be an average not the actual number.

[imafan26]

You know, I give you credit for trying to make your own fertilizer.
I take a different approach. I'd get a soil test first.

Ask for organic recommendations.

They will tell you how much manure, bone meal, etc your soil needs. Hopefully they give it to you per 100 sq ft not in acres, but you can request that too.

http://www.extension.umn.edu/garden/yar ... anagement/

While you are trying to make a balanced fertilizer, it is much harder to do with organic sources since few of them are pure and as Rainbow said their numbers are low. Low numbers are not a bad thing. But remember the numbers represent total N-P-K, and with organics compounds it is a far cry from what is readily available to plants. Good news they become available slowly over time but it may take up to two years for total release. However, even with organic fertilizers, if you apply more than you need to, it can be harmful to the environment,.

You also need to consider because the sources are not pure, you end up with other things as well. Bone meal and chicken manure you get calcium too, which you may not want if you have alkaline soil.

Add only what you need and keep it simple.

Fish emulsion works for me and compost tea as supplements.

[rainbowgardener]

"I got those n-p-k values from the product i purchased. They listed their values. But like you said, it might be an average not the actual number."

That is not what I said. Even if the numbers for nutrient concentration in each ingredient are precise, what you are doing when you add all the ingredients together is adding the total amount of nutrients, but ending up with an average of the concentrations. So if you have one seed packet with 30 seeds, one with 40, one with 50, if you throw them all together you have a total of 120 seeds. But per seed packet (which is the equivalent of concentration) you have 40.

Look at the beer example again. So lets say you have a bottle of beer with 3% alcohol and a bottle with 5% and you pour them together, your pitcher does NOT magically have 8% alcohol (which is more than any of the ingredients had). Your pitcher of beer has 4% alcohol, which is the average of the alcohol concentrations of the ingredients. So when you mix your ingredients together, you are increasing the total amount of nutrients (just as the total amount of alcohol in the pitcher is more than the total amount of alcohol in one of the bottles), but you are not increasing the concentration of the nutrients, which is what the NPK measures, you are averaging it.

Capisch?

And you don't need to redo the numbers, I did them for you. The NPK value of the mixture you describe would be
3- 2.7 - 0.8. No uncertainty, it is straight arithmetic.

[bombcat]

Thanks rainbowgardener, that
"I got those n-p-k values from the product i purchased. They listed their values. But like you said, it might be an average not the actual number." was to answer CharlieBear 's question for "Also you don't say where you got those values from are they on the bags of products you are planning to buy or out of some generalized garden reference." I should be more specific on that.

rainbowgardener, Yes, the number and formula you provided is excellent example (3 - 2.7 - 0.8.). when I say I need to rework my number, I mean I need to redo my spreadsheet to get a more close All purpose number. I actually want a bit higher K, so the 0.8 is a bit low compare to the N and P. Either I will lower the other 2 or increase K to get a more even N-P-K #. I don't mind if it is 1 - 1 - 1.

imafan26, I do understand if I use fertilizers, things might be off sometimes. But it would be the same as adding other brand of fertilizer as well. Atleast doing it myself, it would be cheaper. Sometimes I will have our soil tested. Right now, for the past 2 years, we only use store brought compost, and Dr E. fertilizers, added some garden lime and Azomite. We only use 1/2 or less of the recommended amount. Hopefully it is not too out of wack.
Thank you for the website, I will look into that. But we are not a pro gardener yet. No need to go that extreme.


Thanks again All!

[Susan W]

Bombcat, you are working on an interesting project/mix. If you haven't already, next time you are in a garden center, check the bags of Epsoma brand (plant-tone, garden tone etc) and ready the ingredients and values. I'm trying to use it more as a slow release, plant & soil food.

[bombcat]

Thanks Susan, I wouldnt call it a project. Just trying to save a few bugs here and there. What I did was looked at Dr. E's ingredients and values and tried to figure out what they use.

[CharlieBear]

first I want to apologize for trying to be polite and wondering about the question itself. I think it might have added to the confusion. So, let me be blunt. How much nutrients you need is dependent on what you are growing, the ph of the soil, the soil type and it's tilth. If your soil is acidic you first have to add lime, but if you tend toward alkalinity you don't want to add it. If you are fortunate to have sandy loam then you will need much less additions than if you have sand or clay (the 2 extremes). The very model you are looking at the world through is that of industrialize farming, which strips the ground. If your ground is in good shape, has a reasonable organic content then I am wondering why are you looking at such high NPK values. I thought this might be a prank, $300 on 100 sq. ft. That is only 10by10 (very small area to be dumping that much stuff on). I will tell you what Lee Reich would and he has been doing this for more than 40 years. If your soil is in good shape, you clear it of all old garden debris at the end of the season. Remove diseased plants and water correctly then all you need is 1-2" of good compost every year in a vegetable garden. That can be placed on top of the soil or worked in gently into the top few inches. If you have blueberries be careful of anything not recommended for acid loving plants. If you have cane berries it is best to top the ground right around them with about 2" if composted horse manure or the like in the fall after the berries have been picked and the old canes removes. Fruit trees are a whole other ball game. They need to be taken care of based on their age and size as well as type. But it sounds like you are looking for something organic that acts like time released Miracle Grow. If you really wanted to put that much stuff on 100 sq ft why would you bother mixing it first. I can't imagine using farming equipment to spread it around. Most of the stuff you list in your "formula" are plant materials. These need to compost in the ground before the plants can use what they can provide. Therefore, if you have been adding this much organic matter to the soil every year for 4 or more years. Why do you think you still need this much? Past a certain threshold adding more will not give you healthier plants. In fact, some plant become resistant to high nutrient levels and then require more and more to get the same result. In short they become addicts. As for the compost on top of the ground if it is well composted you can just plant right in it. In fact I have seen people place 4-6" of mushroom compost over a back filled area that only had 2" of good top soil placed on top and have a successful vegetable garden. Over time it rotted down and they simply added other high quality compost to the top and just kept going. (note you don't add mushroom compost year in and year out because it will eventually cause salt related issues). As you can see the actual solution is more complex than you want it to be or simpler than what you are doing, all in how you look at it. The truth is the best organic fertilizer in the world is bat guano (not readily available due to over harvesting). The chemical industry would like organic gardeners to just switch to organic fertilizers and then the industry doesn't lose any money. I agree with "Hawaii" you could just have it tested, but you would have to do every few years to be sure and for 100 sq ft. It isn't worth the money unless you are organic farming. I didn't wade into the math issue, because to do it justice would have taken up far too much space to make it readily understandable. In your case the way to save money, might be as simple as don't over fertilize.

[bombcat]

No, no, no CharlieBear, any input is greatly appreciated!! I thank you again for such a write up. Let me give a bit more information on our garden.

The $300 we spent on fertilizer was not for our 100 sq/ft garden. The 100 sq/ft was used for easier calculation for mixing my own. The $300 was used on different fertilizer like All purpose for veggies for our 1 large (510+ sq/ft) planter, 1 medium (100+ sq/ft) planter, 4 small (21+ sq/ft) planter and a few sections on our land for pumpkins, and many pots my wife has for her indoor plants and flowers. Fruit Tree fertilizers for 5 pear trees, 3 apple trees, 1 persimmon, 6 blue berry bush, 2 black berry bush, some grapes and 2 fig. Rose fertilizers for our 6 roses, I might miss a few items here and there...

Every year we have to buy a few of 40 lbs ($75) fertilizers. And every year their prices goes up. That's why it adds up quickly... Also the instruction on the fertilizers were always a couple of lbs per tree or 100 sq/ft.... once every 6 - 8 weeks or so. That's why I want to mix my own, which can bring the price down.

We also have to buy store band composed cow manure ($5/40 lbs a bag of 0.5-0.5-0.5) because we do not generate enough. So to cut the cost. I would like to mix the fertilizer, but yet only have add a hand full here and there, since the N-P-K would be higher in number and it will be slow release.

This might be over my head and might ended up wasting more $. But if it works out, in the long run, I think I can save some $ on fertilizer. And even if the mix doesn't work, I can still use them separately.

In order to test our soil, we would have to get soil sample all over the place since all the planters, trees and fruits are all over the place. To get reading for all will cost more $....

At one point I did use Bat Guano for our asparagus, but their price has gone up so much this year, I don't think I can use it in my formula. since it will just push the price up.

[rainbowgardener]

To be fair Charlie, re : " I am wondering why are you looking at such high NPK values" it doesn't really sound like bombcat is going for high NPK. Other than the error thinking the NPK's could be added, everything discussed is organic stuff with pretty low NPK's, like the manure and compost, feather meal and other stuff. And s/he did say in the first post "it is getting to be a bit expensive for a large garden (fruit trees, roses, veggie garden and etc...)"

But Charlie has a point about you might be working too hard at it, bombcat. I don't know how many years you have been doing this. If you are starting out new with bad soil, you would need to work hard at lots of amendments. But eventually, you should get to the point where your soil is pretty loose and enriched and you don't have to keep working so hard. I don't use any fertilizers, just compost and mulch. I keep everything well mulched (helps with moisture conservation and weed suppression) and as the mulch starts breaking down, I add more. The mulch breaking down helps feed the soil. And I add compost usually three times a year: at planting, mid-summer, and in the fall. That is it. That is all I do. And I don't pay any attention to NPK. Not only is it pretty low in all the stuff I'm adding, but you can't treat your soil like it is a bunch of chemicals. It is a living organism. Different plants need different nutrient levels/ combinations and the same plant needs different nutrient levels / combinations at different times, depending on whether it is growing, blooming, fruiting, whether it is under heat stress, wet or dry, etc. Adding things like compost and mulch, I am not feeding my plants. I am feeding my soil and the earthworms, microbes and other life of my soil. They will feed my plants, so I don't have to.

One little suggestion, Charlie - If you throw a few paragraph breaks in there, it would make your posts much easier to read on screen. You always have a lot of good stuff to say, but sometimes I really can't deal with reading it that way.

[bombcat]

Thank you rainbowgardener!!

4 years ago, we started our planting, the soil was more like clay, and was bad. We got some harvest, but I have to say its not too good. Each year afterward we add composts, and fertilizers. I think its really like 2 years ago that we started to add organic things. The soil is still pretty hard and pack. but we are able to get more harvest each year.

I read somewhere that mulch will pull Nitrates from the soil when decomposing. So if you add them, wouldnt it lower your Nitrates?

The way my wife plants, it is hard to add compost to the planter 3 times a year. I could only add it before she plants everything. But I can sprinkle fertilizer on the soil around the plants.

But doens't adding organic fertilizers feed your soil too? The fertilizer I got, aren't they mostly plant matters and the earth worms, microbes and other life form can eat it? And it will decompose and feed the soil?

[rainbowgardener]

Sounds like you've been doing a great job and your soil is improving nicely!

RE: "I read somewhere that mulch will pull Nitrates from the soil when decomposing. So if you add them, wouldn't it lower your Nitrates?" Depends on what you mean by "mulch" and what you do with it. Wood chips are mostly Carbon and if they are mixed in to the soil, will definitely pull Nitrogen from it. If they are just on top of the soil and not pressed in to it, won't be as bad, though maybe some effect, where ever it is in contact. But mulch is any organic matter you lay over the top of your soil (actually some people even talk about plastic "mulch," gravel "mulch," but I wouldn't, since those don't break down and feed the soil). So I tend to use a mixed "green" and "brown" mulch - fall leaves and grass clippings, straw and pulled weeds, etc. That way when it all breaks down, it makes a more complete soil amendment, basically composting the stuff in place.

RE: " But doesn't adding organic fertilizers feed your soil too? The fertilizer I got, aren't they mostly plant matters and the earth worms, microbes and other life form can eat it? And it will decompose and feed the soil?" YES, of course to all of that. I wasn't suggesting you were doing anything wrong, just possibly working a little harder at it than you would have to.

RE: "But I can sprinkle fertilizer on the soil around the plants." Better would be to work it in a little bit.

You're doing great!

[Susan W]

Just a note on adding fertilizers and compost. The plants, fruits, veggies etc take out a certain amount of energy, nutrients to grow and produce. If we are harvesting, need to replenish in some way. For a few pots and small garden, one may have enough compost. For larger garden areas, fruit trees and more, need to add. Basic!

If I am reading this right, bombcat is supplementing, replenishing, building the soil. This is the path I am trying to go for also, both containers and ground. What and how added is by needs, convenience and everything else.