"Implications for Organic Agriculture

Foliar applications of water-soluble nutrients are highly unlikely to supply the macronutrient needs (N, P, K, Ca, Mg, S) of plants. Nutrients locked up in the organic form are not readily soluble in the soil solution, and are also highly unlikely to be carried into the cells of the root. Over time, these organic nutrients become mineralised (inorganic) as microbes and soil animals degrade them. However whilst plants may not utilise organic nutrients directly, indirectly organic matter is essential for maintaining a healthy soil (refer to Âcan do sheet 4: What is a Healthy Soil). "

Here is a link that might be useful: source

I am highly doubtful that foliar feeding accomplishes much, if anything.

I have never seen anyone recomend foliar feeding as the -sole- means of fertilizing a plant. If it works efficiently then why not?

I suspect that to the extent some of the nutrients are in plant usable forms some plants may be able to use the nutrients that way, but not most at least not to any significant degree.

I don't know any of the above to be true, it is just what I suspect is true based upon what I have seen/heard/read.

Of course there are significant exceptions like the bromeliads.

Foliar feeding is not myth, but there are so many precautions in place, new OMRI certified neutrally charged amino-acid based chelated mineral formulations improving penetration and efficacy, (as well as the needful collaboration with plant tissue labs), I think it might be wise just to acknowledge this as one misapplication can ruin one's crop without doing the homework and having the appropriate equiptment... Any updated plant physiology text based upon nutritional physiology might shed additional light.

Chelates are very readily absorbed through the foliage, as is my experience with iron. I have often resorted to the quick fix of foliar feeding many kinds of plants, but would never consider it the optimum method of providing elements to plants.

We have an orchid grower nearby who competes with a grower in Taiwan. He has looked at the Taiwanese orchids and found that they have almost no roots, apparently due to foliar feeding. I don't think it is a myth.

Couple this with the idea that there are 10 to 20 layers of microbes living on the outside surfaces of the plants, and you have a lot of variation possible in the way plants take up and use nutrients.

There is a large body o research out there that indicates that the research done to support foliar feeding was erroneous. Apparently the people that thought foliar feeding did work forgot that plants leaves manufacture nutrients by photosynthesis.

There is a large body o research out there that indicates that the research done to support foliar feeding was erroneous.
is this like getting a 2nd opinion?
or is this double or nuttin?
"large body" - real or imagined - no reference to who/what "they" are or call themselves?
sorry I just get a kick out readin these things

All of the previous posters have a firmer grasp of soil science than I do. My experience this year is what I will share. I am making 32 gallons of aerated compost tea (fermented with molasses, sugar, and grass clippings) in a plastic trash can once or twice a week and pouring about 1/2 gallon a week (undiluted) on each of my vegetable plants as a primarily foliar feed, although in that quantity there is a some which runs striaght onto the soil. They are healthier, bigger, greener, setting more fruit, and more disease resistant than any of my previous organic vegetables. Of course, I have a very rich soil as well, but I had that last year and it didn't do what this year's crop is doing.

I thought I read somewhere that research showed that foliar feeding worked best at 72 deg. F and that at this temp., the leaf pores were more prone to open.

...there may be certain situations where foliar feeds might warrant consideration as a supplemental approach...does not suggest a replacement for soil-based nutrition..
ref:Mineral Nutrition of Higher Plants 2nd.ed(2002);Horst Marschner;Chapter 4;(4.3);
...minor correction referencing "OMRI Certified" The above reference
of the amino-acid based mineral formulations - approved for Organic Production under the Washington State Department of Agriculture verified to comply with 7 CFR,Part 205 USDA /National Organic Program...(Current status unknown...)

A quick request for of the search engine resulted in 45,000 plus pages of stuff on "Foliar Feeding" and a look at some of that showed that the vast majority of those were written by people with some kind of foliar plant food to sell. However I have read many research papers in the last 5 years that do show this foliar feeding simply does not work and they should be available. It may take patience to find them.

Sonic Bloom works partly with foliar application but if I remember right they say that they have a special formulation that dissolves the waxy cuticle

try:"Scirus for scientific information only"
http://www.scirus.com/srsapp/

keywords:"mineral foliar sprays"
or such....

Here is a link that might be useful: scirus search engine

I do enjoy intelligent discussion.
--Apparently the people that thought foliar feeding did work forgot that plants leaves manufacture nutrients by photosynthesis. Think so?
--A quick request for of the search engine resulted in 45,000 plus pages of stuff on "Foliar Feeding" and a look at some of that showed that the vast majority of those were written by people with some kind of foliar plant food to sell. However I have read many research papers in the last 5 years that do show this foliar feeding simply does not work and they should be available. It may take patience to find them. Now are we recruiting?

Let me summarize -
Ok so you don't agree with the subject of the post. So you post to say you disagree. Nothing wrong with that. That is how we learn - from each other.
So then people post to attest to their positive results.
--you post again to say A quick request for of the search engine... no clues given to the search 'request' of his choice. But hey Google has "Results 1 - 10 of about 233,000 English pages for Foliar Feeding." So hey try Google.

So you decide to post back to say "45,000 plus pages of stuff on "Foliar Feeding...", however none of them support your claim. And then you close by "It may take patience to find them." asking someone else to find your unsupported claim?

roflmao... but when I get up off the floor, hey I'll get right on that for YOU.

Please promise me that if I go into a coma, someone WILL unplug my keyboard, PROMISE ME.
Thanks

A google on 'foliar feeding' shows me a university article and a private article claiming that foliar feeding is more efficient than soil feeding for fast corrections of nutrient imbalances.

Interesting.

http://www.ext.vt.edu/news/periodicals/commhort/2002-11/2002-11-03.html

thank you for a succinct post and very good reference,username...(new formulations,neutral in charge,adjuvents and compatable molecular configurations to improve penetration and efficacy at lower rates...

"Although most plant nutrients are absorbed through the roots, plants can also absorbe nutrients through the leaves, apparently via the stomates. Sometimes this happens in nature-rain water, particulary during thunderstormes, contains small amounts of dissolved nitrates and other nutrients readily absorbed by plant leaves. Gardners can foliar-feed by spraying leaves with dilute solutions of fish emulsion, seaweed extract, manure tea, or other fertilizers. Plants respond rapidly to such treatments, looking greener and healthier within days."
RODALE'S ALL-NEW ENCYCLOPEDIA OF ORGANIC GARDENING copyright 1992
This topic has been discussed at length on the "Organic Gardening Magazine" forum and some responce to the above quote had been that the informating is no good as the copyright is 1992. So there is currently ongoing research in the OGM gardens, results pending. However, the magazine printed an article recently in which the scientist/researchers did note several phases of plant life in which foliar feeding appeared to have positive results. Next time I'm at the library I'll try and copy the article so I can provide more accurate and detailed information. My personal experience using foliar sprays for the last 10+ years concur with the above quoted material.

"...there is currenty research in the OMG gardens,results pending...." please excuse, what do you mean by "pending" then...The Q/A and my participation is that the administration of formulated mineral foliar sprays is not myth....and furthermore,despite advances in new plant absorption technology, this method has been used for quite a number of years....

...if you are off to the library, try to procure the second edition of Mineral Nutrition of Higher Plants,(Horst Marschner) through your inter-library loan system ...See references above and use the index to address foliar applications of Boron,Molybdenum deficiencies (for examples) pertaining to proper seed set/viability at least.......The index will also provide further suggestions of what else should be considered prior to reading product labels; proper equiptment;MSDS factsheets; Worker Safety Protection Standards and so forth....

Pickwick, pending as in the crops are currently growing. The following is from Scott Meyer, of ORGANIC GARDENING MAGAZINE, concerning research currently being conducted at the Rodale's gardens. This is from a forum discussion on foliar feeding:

Posts: 179
Registered: 2/11/02
Re: Scott Meyer: Foliar Spray update please
Posted: May 2, 2006 12:31 AM Reply

"We are testing foliar feeding this year, Peggy, but it is way too early to report any results. We have been feeding seedlings in the greenhouse with different formulas - compost tea (regular and aerated), fish and seaweed, fish emulsion, kelp, and that very easy to apply product known in Spanish as "nada."

We can see some slight variations in the growth of the seedlings, but I don't think that's enough to draw meaningful conclusions. I want to see if there are differences in productivity and performance through the whole season to determine if foliar feeding has a significant affect. We won't be planting out our tomatoes and peppers for another two weeks - we have had a threat of frost here in southeastern Pennsylvania for the last 3 nights.

We'll see what the test results are..."

Thanks for the book suggestion Pickwick.

Miracle gro seems to do pretty good as a foliage feed. I don't need scientific study for something I can see with my own eye's!! If plants are wilting in the heat and you spray a little water on them they perk right up. The water, and nutrients, must be getting in somehow.
Before you jump on me for the miracle gro. I have not used any since I started reading the organic forum. But still trying to find something to replace it that works as well. New lasagna beds, still breaking down,could use a little boost. And no one here seems to know how to apply compost tea or stinging nettle tea with a hose end sprayer.

Lee

As far as myth goes I would say no way. It has been used by many growers of ag crops for way too many years for them to use it with out seeing useful and productive results. The waxy cuticle is a hinderance and the only time to foliar feed these types of plant effectively is during new growth cycles. The new growth has readliy transpires water as seen by wilting of new growth from lack of water. Less evident without new growth. I had a nursery in Hawaii for 10 year and used seaweed and other chemical products with excellent results when foliar feeding during new growth cycles on avocado and mango both of which have a waxy cuticle than inhibits transpiration. It was very effective in curing micronuturient induced chlorosis problems with zinc, iron, boron, and manganese. Leaf samples taken at various intervals throughout the year supported this practice. It has been common to foliar feed citrus and avocado in California for many of these same problems and again the science behind it at that time (1986-1996) supported this practice. I will admit I have not used the internet to track down any of that research that I was familiar with long ago before the internet and most of it was through ag trade magazines at that time.
The biggest drawback in my humble opinion is the extra labor input as opposed to feeding through irrigation lines makes the cost too high unless it is the only way you can supply those given nutrients because of inbalance of ph or other factors existant in the soil or growing medium.
I have used seaweed to great effect since moving to Texas and generally time my spraying to the 6-7 am window during the summer months. Tomatoes have worked very well for me and I may do a control for fall just to how much more productive I can make the same variety under equal treatment except for foliar feeding. Question the practice all you want but do some real ag related research before you discard this as useful technique.
David a garden center manager at Canyon Lake

Foliar Feeding,

Would someone present a paper on how the nutrients penetrate the leaf epidurmes(sp) and then the systemic flow from the leaf to the roots and then back to that plant parts that need the nutrients.

I have seen the vascular flow of nutrients in a dicot, everything flows from the roots to leaf or fruit tips.

Sugars from photosynthesis flow from the leaves.

A Dr Mary Peet, NCSU, did a study several years ago and said that only nitrogen could be passed thru the leaves but not enough to make it economicaly feasable for a commercial grower.

I suggest a textbook based on nutritional physiology... Run a search of my suggested reference and see how this scientist is evaluated on the internet....

"Would someone present a paper on how the nutrients penetrate the leaf epidurmes(sp) and then the systemic flow from the leaf to the roots and then back to that plant parts that need the nutrients."

Here is a link that might be useful: full2004-24spec.pdf

dilbert

I read thw whole thing.

A couple thoughts, most of the work was done with fruit trees, Special formulations are needed like K was mixed
with a citrate. Calcium was either calcium chloride or calcium nitrate, not calcium carbonate. Most of the minerals were chelated. This means that the study was NOT done with mirical grow.

Fruit trees are not dicots, like peppers and tomatoes.

I also think that the Conclusion, says it all.

Well,

one way to determine if foliar feeding would work would be to grow whatever plant from seed or cutting in vermiculite and provide only water until it shows obvious symptoms of nutrient deficiencies.

Then, spray with whatever nutrient sourceone prefers taking care to cover the vermiculite and see what happens.

Cheap, easy, backyard experiment for those interested in foliar feeding of their plants.

I would think corn would be interesting since it is so cheap and such a heavy feeder.

If nothing else, this discussion has prompted me to go give my baby okra, grown in a raised bed with all the compost, soil amendments,mulch, etc. that I have been able to provide over the last 10+ years, a nice foliar and soil drench of fish emulsion and seaweed extract. This time of year in my Fl. garden the rest of the garden is over. I'd plant southern peas, but have grown tired of the cowpea curculio ruining most of the crop. I hope to foliar spray the tomatoes and peppers tomorrow which often results in an additional fruit set, but the high temps are hard to overcome. Time to get seeds going for the fall planting. Hope all of you had a nice 4th.

Fruit trees are not dicots, like peppers and tomatoes.
Fruit trees are dicots, infact, most non-gymnosperm trees are dicots. The only non-dicot tree that could even be considered a fruit tree is a ginko. Dicot simply reffers to the number of cotoledons (sp) on the seed, when you plant say an apple tree the first two fleshy leaves would be the cotoledons, just like in a bean or a tomato. Perhaps what you meant to ask is for some evidence to show how nutrients are moved through herbaceous dicots.

The fact is that you probably know that some nutrients are moved from leaf to leaf, some nutrient defficiencies only show up in older leaves, ones that are already established and contain all of the nutrients that they need, this is because the plant directs nutrients towards the newer growth and all that direction drains them from the older growth, so if you have nutrients in a form that the plant can transfer and you manage to get them in to the leaves the plant can move them were it needs them Every plant has tubes running in both directions, barring mechanical damage or desease that can do what they need to do most of the time.

...suggest precautions....Chapter 11(Marschner)(Relationships between Mineral Nutrition and Plant Deseases and Pests), correlated with the same theme presented in Plant Pathology;George N.Agrios (see nitrogen/ (nitrogen forms) excesses)... One can easily cause nutrient imbalances from applying excesses(in this case:foliar feeds) of particular nutrients and set the stage for subsequent attacks of pests and diseases...
keywords:luxury consumption; nutrient toxicity yielding nutrient imbalances
goodluck

"Apparently the people that thought foliar feeding did work forgot that plants leaves manufacture nutrients by photosynthesis."

What does the photosynthesis of one nutrient--sugar--in the leaves have to do with whether plants can use other nutrients, like minerals, applied to the leaves?

Some of the older biology says that the phloem was unidirectioonal, now some studies claim that the it is bidirectional. At this point I am not sure what to believe ..

Maybe the way to find out is to get a bottle of sudsy ammonia, put some in a hose end sprayer and spray a small area of your yard and see what happen. I was speaking with a golf course manager and he said that he spays the course with liquid iron before a major tournament, he also mentioned that it was to make the grass a deeper shade of green, but it was not long lasting, how long I don't know. I also don't know if he adds anything to the iron or not, I saw the product and I was surprised to see it was from Germany, I don't remember the name of this product but the color was black and it stained my hands. He also mention something about molasses as well, but I have forgotten how he used it. I believe ammonia is liquid nitrogen, if not someone let me know. I have learned a lot from reading this post, I have save all the links for later reading. I want to thank you all for such an engaged discussion. I did not see one post that was not interesting, and that is rare. I guess my post is the least interesting one, sorry.

"Some of the older biology says that the phloem was unidirectioonal, now some studies claim that the it is bidirectional. At this point I am not sure what to believe .. "

Possibly, plants evolved the capability to transfer some nutrients down the phloem in order to recycle nutrients from senescent leaves before the leaves die. It is well known that such leaves have a high amino acid concentration. This is probably the result of an effort to transfer nitrogen to new growth.

"Some of the older biology says that the phloem was unidirectioonal, now some studies claim that the it is bidirectional. At this point I am not sure what to believe .."

Even if phloem were unidirectional, that direction would be FROM the leaves TOWARDS the roots (glucose created in the leaves through photosynthesis travels through phloem to the rest of the plant--this is the main function of phloem). But phloem transport is generally believed to work by diffusion, which means wherever you introduce nutrients into the phloem, they will spread to the rest of the plant. Some nutrients are known to be phloem-mobile--I believe they include calcium and manganese.

I have never heard of phloem being unidirectional. I have always read that xylem is unidirectional because it works by capillary action--from the roots up--and phloem isn't really "directional" at all.

At what point do nutrients going down a phloem in one leaf, cross over to a xylem to go up into another leaf? Or, is it down one phloem followed by up another phloem?

dilbert, that's a good question. I remember when I was reading about this earlier that there was some evidence of nutrients crossing over from phloem to xylem. But diffusion would cause the nutrients to spread throughout the plant's whole phloem system--they would keep spreading until they reached a constant level throughout the plant.

Does foliar feeding happen in nature for plants as a whole (the special case of tropical plants not rooted in soil is accepted) ? If so, whence the nutrients? dust? air-borne fungi? Not, obviously, the custom blends that are crafted by agribusiness. I am conviced that it works; many organic farmers attest to that. But I hesitate to use something that might have no natural equivalent. Regards, Peter.

"I hesitate to use something that might have no natural equivalent."

Why?

boxbeast: a very good question for which I don't have a thoroughly rational answer. But here goes. When I'm in two minds about a process, practice, or such things as soil additives, I always provide myself with a provisional answer by asking if it's natural. Now I know full well that gardening is a very unnatural process. Just compare how domestiated plants fall prey to disease and insect pests, for instance, wheras weeds resist them all the time with no trouble. (Here's wonderful scope for study of plant's natural resistance, and how we might restore it to domestic plants).

But at least what is natural has been tested by literally hundreds of million years of evolution (including co-evolution) so has the wisdom of eons of trial and error and the success of survival. So that's why 'natural' is my touchstone in a pinch. In other words, if - on any issue - a gardener thinks he has a better answer than Mother Nature, he/she had better be very, very sure of the reasoning. This is doubly so when we consider how little we know about what goes on in plants and in the soil. If we tinker with one thing, we should consider the ten consequences that we are unaware of. Regards, Peter.

Natural equivalent?

Rain water wets entire plants not just roots.
Rainwater is mysteriously more effective than normal fertilization. Rainwater is usually ionized through lightning.

You are thinking in terms of liquids. Leaves have evolved to be able to extract oxygen, nitrogen and C02 from air directly. Water was its first domain and most of the plants still have the ability to do so. Green algae have no roots. Aquatic plants or halophytes have roots but nutrients in the form of ionic solutions donÂt need to reach the roots to be absorbed. In aquatic plant keeping you will learn that you don't need to circulate your water (that has nutrients added) through the substrate, even if the substrate has no nutrient base at all. The plants sucks nutrients out of the water equally as fast, there is no difference.

Some halophytes you find in aquatic plant keeping you wonÂt find growing in water when you go look for them in the wild. The only differences between a halophyte and a non halophyte plant is that their skins are adapted not to dry above water or to be able to access dissolved gasses below water. The one adaptation messes up the other ability.

So in my opinion, plant foliar feeding will vary between plant species. Tough waxy plants will be less effective while soft fast growing, higher humidity or "higher plants" will be more effective at utilizing foliar feeds.

Controlled studies exists but is probably so old you won't find them on the net. It's common knowledge in my opinion.
Maybe someone should post some fresh studies.

I was reminded the recently by a program on LINK, I think, of the cactus in the cloud forests in the high deserts Andes where there is rarely any measurable precipitation but clouds almost all the time. Some areas have quite lush cactus and succulent vegetation.

When you "foliar feed" at home, it also runs off on the ground, therefore, I doubt you can use results as evidence that it works by that mechanism. Having said that, Roundup sure works well when "foliarly" fed! And I also think it makes it down to the roots from the leaves.