Fish fertilizer is very popular. It is reported to be a good source of nutrients and a good source of proteins, amino acids, and oils—for your plants. Can plants use fish proteins and oils? Is fish fertilizer a good source of nutrients?
Before I go any further, let me say that there is nothing wrong with using fish fertilizer. It will help make your plants grow. I have two problems with fish fertilizer: it is extremely expensive compared to other sources of fertilizer, and many of the claims for it have no basis.
Fish Emulsion vs Fish Hydrolysate
What is the difference between fish emulsion and fish hydrolysate? The difference from a plant’s point of view is minor, but if you are trying to sell product, there are big differences.
Fish emulsion and fish hydrolysate start with dead fish. In some cases this is leftover bits from the fish industry, and in other cases, this is whole fish specifically caught to make fertilizer. These are then treated with various chemicals and enzymes to break down larger organic molecules into nutrients and other small organic molecules. Further treatment can take one of two paths; it is either heated or cold processed. Fish emulsion is the end product if the heating process is used. Fish hydrolysate is the result of using cold processing.
There is great debate between the benefits of emulsion vs. hydrolysate—which is better? The reality is that plants can’t use most of the large or even small organic molecules from either process. Normally microbes in the soil degrade these to nutrients plants can use. So the argument that heat in the emulsion process is detrimental makes no sense. It is true that heat will denature proteins, but they need to be denatured for the plants to use them.
I think the arguments for or against either process are just marketing hype. I have seen no scientific evidence to support the superiority of either process.
Fish Fertilizer Benefits
Fish fertilizer is an organic product—for the most part. So it does have the benefits other organic soil additives have. It feeds plants and microbes and improves soil structure.
But proponents of fish fertilizer make claims that do not apply to other organic fertilizers. Most seem to be centered around the fact that the liquid fertilizer contains proteins and oils. We all know fish oils are very important for our health, so they must be good for plants, right? Wrong!
Plants can’t make use of large molecules such as oils and proteins; see Organic Fertilizer—What Is Its Real Value? for more details. When these molecules are added to soil, microbes digest them and turn them into small molecules like nitrate and phosphate. It is only then that plants can make use of these molecules.
Since the large molecules need to be degraded before plants can use them, there is little difference—to the plant—between proteins and oils from fish, cows (manure), or even plants. I have found no support for the claim that fish fertilizer is better than any other organic fertilizer.
The main thing plants need from fertilizer is a source of nitrogen. Garden soils usually have enough P and K and the other minor nutrients. Nitrogen is the thing that is missing in soils. Given this fact, fish fertilizer is no better or worse than other types of fertilizer.
Fish fertilizer has about 2% nitrogen, which is the same as most organic fertilizers: compost, manure, and coffee grounds.
Is Fish Fertilizer Organic?
This probably seems like a dumb question—fish are organic, so why would fish extracts not be organic? Here’s why. In the process of turning fish scraps into fertilizer, companies add a number of chemicals, including phosphoric acid and odor inhibitors. Apparently, as long as these ingredients form less than 1% of the finished product, the product can still be called organic. Who knew—organic fertilizer only needs to be 99% organic!
Cost of Nitrogen
I checked several fish fertilizers, and a common analysis is 2-4-2, and if you buy in large containers, you can get 9 lb (3.8 kg) for $25. Small quantities are even more expensive. This fertilizer has 2% nitrogen, and so the cost for the nitrogen is $33 for 100 g of nitrogen. Wow! Even fresh-caught Atlantic salmon doesn’t cost that much!!
What is the cost of 100 g of nitrogen if you buy a commercial fertilizer? Scotts sells a 30-0-9 at $17 for 6.2 kg, or $0.91 for 100 g.
Fish fertilizer is 35 times more expensive than commercial fertilizer, and plants can’t tell the difference between the two sources of nitrogen.
I can hear your objection, BUT … fish fertilizer is organic. That is true, and organic fertilizers do more than just provide nutrients. They also help build better soil by feeding microbes. Fish fertilizer is about 14% protein, which is the same as manure. A 30 lb bag of manure will cost you $4 compared to $75 for the same amount of fish protein. Manure bought in bulk is even cheaper.
I really can’t think of any good reason to buy fish fertilizer if other sources of fertilizer are available.
References:
1) Photo Source: Cheryl’s Garden Goodies
I was wondering if there is a way to get rid of the fish smell in my fertiliser?, If so I would love to know… either way a solution to reduce the odour.
Thank you!
I don’t think so.
Yes , you can add 1tbs of lactobacillus serum and after around 30 mins the smell will be gone
I noticed that after being given fish fertilizer, the leaves of my avocado experienced a high level of “salt tip burn.” Avocado is very sensitive to salt. Given the expense and the other considerations in your fine article I plan to go back to pure ammonium sulfate.
Your problem has nothing to do with fish fertilizer. You probably just added too much. This will happen with any fertilizer. for sensitive plants, always use half of what is recommended, or even less.
Although useful for many human purposes, ammonium sulfate poses some health risks to humans and animals and requires careful handling. The primary use of ammonium sulfate is in commercial pesticides and fertilizers. This substance dissolves rapidly in water, but not in alcohol and other synthetic mixtures, making it a solid addition for stabilizing fertilizers. Ammonium releases upon exposure to water and can make its way into the air in the form of ammonia gas.
After application to damp soil, ammonium particles escape, causing an increase in the acidity level of surrounding soil. The rising acidity creates a lower pH level in the soil, increasing growth of plants and crops. The introduction of ammonium sulfate to soil also produces nitrogen, which encourages rapid growth of plants.
Ammonium sulfate dissolves less readily than many other natural and synthetic compounds, making it an economical choice for a cheap fertilizer ingredient. This compound also serves as an herbicide by searing and ultimately killing the leaves of plants, making their removal easy. Ammonium sulfate also appears in processed breads and acts as an additive in many foods.
REF: https://www.reference.com/science/ammonium-sulfate-uses-1c26495629b2a8d5
I had 3 ace’s of jackfruit and l’m using fish emulsion fertilizer for the past 4 years.lt have help me solved a lot of problems such as insects ,dry branches,small fruit,quality of fruit that like rusty and very hard soil.lt cheap to use,1liter l can mix 200liters of water and it cost only RM 212.00 for 20 liters
Imagine how much cheaper real fertilizer would be?
Depends on what country. Chemical fertilizers in Asia can be FAKE and also controlled by CARTELLS and become 4x more than fish.
Chemical Fertilizer also hardens the soil over time and lowers the PH.. The man is talking about a FARM not a garden.
Chemical fertilizer does not harden the soil. Nor will it lower pH unless it contains a lot of acidifying ions like sulfates.
While it is technically correct that chemical fertilizer probably does not harden soil, chemical fertilizer does not add humus which is critical for many soils to prevent hardening. It is also true that our vegetables have between 30 and 50 percent less nutrients since we have been relying on chemical fertilizers.
I have always said organic fertilizer is better than synthetic – but not for the reasons most people claim. Organic matter will prevent hardening of soil by allowing nature to create soil aggregates.
Food today may be less nutritious, but it does not contain anywhere near 40 % less nutrients. The reason for a drop in nutrition complex and variable, but it is not due to the use of synthetic fertilizers.
It is easy enough to do a search. I got 800,000 results for “do vegetables have 40% less nutrients than they used to?” There is a lot of variance but I counted on the USDA figures. Nutrient analysis has been done since the 1920’s so they do know when it changed. The car replacing the horse and the rise of petro-chemical fertilizer are the 2 most obvious reasons.
Just because you get a lot of hits on google means nothing.
Re: “The car replacing the horse and the rise of petro-chemical fertilizer are the 2 most obvious reasons.” – they are only obvious because you think they are obvious.
Well, it has nothing to do with my opinion, I did tell you how to find out what the people who study this think. Maybe you could make a case for what is causing the loss of nutrients since you are so sure of what it is not. The very basis for organic growing is healthy soil for healthy crops. If our crops are 40% less nutritious we are starting to have a problem.
Greetings, I enjoyed reading about your comparison of fish hydrolysate to other forms of fertilizer, the N produced and uptake by plants. A concern for me is in producing homemade FH, oil remains. You state (correctly so), oil must break down via bacterial conversion and it is a task in soil to do so. The bugs hate to expend unnecessary energy. Have you heard of a way to remove or in-process break down the oil in creating a FH, cold versus cooked?
Try looking for some Youtube videos. I don’t do it myself.
Living in Ontario, we always use our local CoOp to buy our organic soil supplies. Kelp(K), molasses(carbs), Alfalfa(N), corn(N), Floating fish food Atlantic Ocean sourced(N)$55 for 50lbs and of course Epsom Salts! We brew our cut grasses, nettles and comfrey during the season and finish off with fallen rotten Apple and over sweet Bannana brew for a finishing kick into high gear for the microbial life to really shine in the art of living soil! yee haw!
Is $55 for 50 lbs a good price? unless you convert this to a $/lb of nitrogen you have no way to know.
Is the fish fertilizer made from fresh caught fish? See Fish fertilizer – Is it Damaging the Environment? for more details on this important point.
I also thought that those who argue that organic fertilizer is better might like to know that 1/2 of the nitrogen introduced by fertilizer produced by the Haber process is not assimilated by plants, and therefore ends up somewhere else in the water cycle. Often this can result in eutrophication of ponds, lakes, and even oceans which can result in fish kills and other aquatic plants dying off.
There is also a unique problem known as “blue-baby syndrome” which results from infants consuming water containing excess nitrogen that binds to hemoglobin and restricts oxygen uptake by red blood cells.
Here’s a link to a great TedTalk that explains the Haber process and mentions the problem of incomplete nitrogen uptake by plants.
http://ed.ted.com/lessons/the-chemical-reaction-that-feeds-the-world-daniel-d-dulek
The incomplete use of nitrogen is not just a problem with commercial fertilizer. The same thing happens with organic fertilizer. Any nitrogen that is not consumed by plants will also be washed through the soil into water systems.
Some of the excess nitrogen also ends up being converted back to N2 gas.
This is one reason to develop a good soil with enough organic matter, which in turn provides the conditions needed by microbes, which can use excess nitrogen not used by plants.
ok, here is one for you, and please dont judge the author of the post regarding this interesting concept of using ocean water as fertilizer
http://www.smilinggardener.com/sale/sea-minerals-fertilizer?awt_l=KMlHc&awt_m=3asaAHSl0B2DE1m&utm_source=aweber&utm_medium=email&utm_content=20160716&utm_campaign=broadcast
I have three problems with the reference:
1) It is just an ad to sell stuff – so it is highly suspect.
2) It gives no scientific references of published information to support their claim.
3) They don’t seem to mention the fact that sodium in the sea salt is toxic to plants.
Most soils re not deficient on the minor minerals – plants need very little of these.
Sodium is a macro nutrient…a cation. Granted soil structure needs less of it than other cation macronutrients (Calcium, Potassium and Magnesium). Plants need it to function properly…along with all the co-factors of micronutrients and anions to make it all work.
Your philosophies espoused here lead to additional Fungicide sales…which in turn lead to more fungicide sales. Fungicides lead to pythium, rhizoctonium, fusarium and a host of other bad guys that cause SDS, Goss’, mildew, rust, anthracnos, etc. In my decades, I’ve found there’s more to a biological system than pure chemistry and/or biology.
Give mother nature a bit of what she wants and get the heck out of the way. Work against her and she will still win…eventually.
Not sure what your point is? As far as plants are concerned sodium is not a macro nutrient, in fact it can be quite toxic.
None of my philosophies promote the use of fungacides?
Thanks you for sticking to science. No amount of sea water is going to help increase production of growth, fruits, grains and flowers.
Mimi’s question about other nutrients that plants need besides those provided by organic material brings up a point that I need some clarification on. Native mineral based soils and their importance to plant cultivation in the home garden.
I and my sister live in California (born and raised thank you very much), notorious for heavy clay soils with high pH. By one website’s assessment (based on web postings), we must be the coffee ground amendment capital of the US.
I live in the Sacramento Valley, she lives in the Mt. Tehema volcanic zone, almost in the shadow of Mt. Lassen. Our soils are very different, but have the same problem in both soils being heavy clays. Hers are volcanic (dacite, andesite), mine are chiefly granitic (washed down from the Sierras mostly). They are high in trace nutrients and metals (but in different proportions), and are well weathered so these nutrients should be available, but aren’t really.
I had a problem with iron chlorosis and some research showed that I needed to decrease the pH of my soil in order to make the iron available—the iron is there, it just isn’t being taken up by the plant roots. Hence the coffee grounds, which seemed to work actually. I also added more organic amendment since it was clear that I hadn’t added enough when I first prepared the soil for planting, and that cured the problem. The coffee grounds were a stop gap (though I still keep some around in a separate compost just in case).
My sister seems to have a different problem—low potassium. Her vegetables and other plants fail to flower or only put on a few weak flowers. She uses compost she made herself blended with the native soil. Her soils contain potassium (moderate levels), but the plants aren’t taking it up. It might be that her soils aren’t sufficiently weathered to make the K available, but I’m wondering if she needs to do something else to help with K uptake. Might her soils also be too alkaline, as in my problem with iron uptake?
Myth? I have had people tell me that the native soil is unnecessary and if it is a problem soil, like here, then I should dispense with it altogether and use nothing but potting soil and compost in raised beds. I don’t buy that. Nature seems to do okay with mineral-based soils as long as there is some organic matter in the mix. I feel it is important to use the native mineral soil. Yes? No?
First of all, although coffee grounds are a good organic addition to soil, they don’t lower the pH – that is a myth.
https://www.gardenmyths.com/coffee-grounds-acidifies-soil/
In everything you say, I did not hear you say you had your soil tested? If you did not test your soil, your conclusions about what is low or high may be wrong. Start with a soil test.
Chlorosis is actually NOT a sign of iron deficiency. When the plant can’t get enough iron it will show something called interveinal chlorosis – they are not the same thing. Even if you had interveinal chlorosis, it does not mean you had an iron deficiency. High levels of other nutrients can tie up the iron and keep it from plants.
Looking at leaves is a popular way to identify a nutrient deficiency – but this does not work. There is almost no nutrient deficiency you can identify this way.
A pH under about 7.8 will grow most plants just fine. The exception are some acid loving plants. I grow almost everything in 7.4 clay.
Even if you made raised beds, the recommended addition to those beds would be native soil. You might add extra organics, but it should still be soil based, especially in your climate. Potting soil drys much faster than clay soils.
Adding organics will buffer things in soil. It buffers pH and it buffers the availability of nutrients. Keep adding organics. If a soil test shows a deficiency – correct it with fertilizer.
I am a supplier of liquid fish fertiliser in Darwin Australia to all the big scale farmers. Do u reckon $2 per litre for a perfect quality fertiliser is good?! Just need to know whether my costing is good.
Without knowing what is in the 1 litre – no one can answer your question.
In regards to the sustainability and sourcing of fish fertilizer products, I like the model that Carpe Carpum out of Idaho uses, i.e., capturing invasive European carp that have infiltrated the local eco system and turning it into fertilizer. The method they use is cold-hydrolysis, which seems to me a better option then emulsion methods.
Here is an article from Sunset magazine. As an interesting sidenote, the company harvests fish from Malheur Lake (recently in the news) as one of the approaches to cleaning it up.
http://westphoria.sunset.com/2015/07/09/the-best-organic-fertilizer-its-made-from-fish/
The idea is a good one. Removing an invasive species and using it productively is excellent.
I do have a problem with the company. They provide no information on their web site about what is in the product so you can’t evaluate the product and the cost. Secondly, the little they do say on their web site shows they don’t know much about fertilizer and plants. Hopefully this will improve as the company matures.