Anonymous User
Banned
After the recent debate on wound sealants, King Kong is determined to debate another myth I mentioned in my article, "Debunking the Myths of Bonsai" which is folair feeding.
I'll just cut to the chase and start the discussion with a direct quote on the subject from my article:
"Foliar feeding at first glance seems almost romantic; the thought of delivering nutrients directly to the foliage instead of though the soil, roots, and up the trunk to the foliage seems idea. The soluble fertilizer companies, seeing possibilities of increased sales, since foliar feeding uses far more of their product than traditional feeding practices, are quick to tout such claims as immediate results, prolong bloom times, increased pest and disease resistance, and even increased crop yields.
The problem is that most of these claims are based on some research done by Michigan State University in the 1950's in which, by the use of raidolabeled nutrients, it was determined that the leaf is a very efficient organ for absorption. The amounts absorbed were actually very low but the efficiency was high, leading to false claims that foliar feeding was many times more effective than soil applications.
Linda Chalker-Scott, an Extension Horticulturist and Associate Professor at the Puyallup Research and Extension Center of Washington State University, clarifies this in her article, "The Myth of Foliar Feeding."
"Obviously, materials applied directly to a leaf are more likely to enter the leaf in large quantity than the same materials applied to soil. Leaching, chemical reactions, microbial activity, etc. can decrease what actually reaches the roots and is taken up into the plant. But material applied to the leaf do not necessarily travel throughout the entire plant as effectively as they do through root uptake. The often remain in the same or adjoining tissues but travel no further. This is especially true of those elements recognized as "immobile" within plant tissues (apart from root uptake and xylem transport)."
Linda goes on to state that the nutrients plants need the most of are the very ones that cannot be absorbed in large enough quantities by the leaf to do any good, such as nitrogen, phosphorus, and potassium. She also specifically states some facts based on research that may surprise many bonsaists, such as:
Tree and shrub species differ dramatically in their ability to absorb foliar fertilizers.
Micronutrients are the only minerals that can be effectively applied by foliar feeding and too much of these can damage or kill a plant.
Foliar spraying is only a temporary solution to the larger problem of soil nutrient availability.
Any benefit from foliar spraying of landscape trees or shrubs is minor considering the cost and labor required.
The common myth of foliar feeding is based on misreading and/or misinterpreting research done over 40 years ago. Since that time it has been shown that foliar feeding is ineffective in almost every aspect promoted by the companies that sell products designed for the practice. In fact, foliar feeding has been shown to work the best only in the case of soil with low nutrient availability, in other words, when a plant has no other option for nutrients. As bonsaists, our soil would never reach the level needed for foliar feeding to do any good.
Bonsai need nitrogen, phosphorus, and potassium the most, as do any other plants and these nutrients are the very ones that foliar feeding is the worst at providing.
It is my personal opinion that any success by bonsaists using foliar feeding can be directly attributed to the mixture running off onto the soil, not through absorption through the leaves. The common practice of watering from above and dosing the foliage puts the nutrients into the soil, even though the bonsaist believes they are foliar feeding."
I, as always, would welcome rebuttal that is based on at least the same quality references, sources, and research as presented. As always, I would love being proved wrong as much as I love being proved right, either way, our knowledge and understanding of the subject is increased. No matter the outcome of these debates, we all win.
Will
I'll just cut to the chase and start the discussion with a direct quote on the subject from my article:
"Foliar feeding at first glance seems almost romantic; the thought of delivering nutrients directly to the foliage instead of though the soil, roots, and up the trunk to the foliage seems idea. The soluble fertilizer companies, seeing possibilities of increased sales, since foliar feeding uses far more of their product than traditional feeding practices, are quick to tout such claims as immediate results, prolong bloom times, increased pest and disease resistance, and even increased crop yields.
The problem is that most of these claims are based on some research done by Michigan State University in the 1950's in which, by the use of raidolabeled nutrients, it was determined that the leaf is a very efficient organ for absorption. The amounts absorbed were actually very low but the efficiency was high, leading to false claims that foliar feeding was many times more effective than soil applications.
Linda Chalker-Scott, an Extension Horticulturist and Associate Professor at the Puyallup Research and Extension Center of Washington State University, clarifies this in her article, "The Myth of Foliar Feeding."
"Obviously, materials applied directly to a leaf are more likely to enter the leaf in large quantity than the same materials applied to soil. Leaching, chemical reactions, microbial activity, etc. can decrease what actually reaches the roots and is taken up into the plant. But material applied to the leaf do not necessarily travel throughout the entire plant as effectively as they do through root uptake. The often remain in the same or adjoining tissues but travel no further. This is especially true of those elements recognized as "immobile" within plant tissues (apart from root uptake and xylem transport)."
Linda goes on to state that the nutrients plants need the most of are the very ones that cannot be absorbed in large enough quantities by the leaf to do any good, such as nitrogen, phosphorus, and potassium. She also specifically states some facts based on research that may surprise many bonsaists, such as:
Tree and shrub species differ dramatically in their ability to absorb foliar fertilizers.
Micronutrients are the only minerals that can be effectively applied by foliar feeding and too much of these can damage or kill a plant.
Foliar spraying is only a temporary solution to the larger problem of soil nutrient availability.
Any benefit from foliar spraying of landscape trees or shrubs is minor considering the cost and labor required.
The common myth of foliar feeding is based on misreading and/or misinterpreting research done over 40 years ago. Since that time it has been shown that foliar feeding is ineffective in almost every aspect promoted by the companies that sell products designed for the practice. In fact, foliar feeding has been shown to work the best only in the case of soil with low nutrient availability, in other words, when a plant has no other option for nutrients. As bonsaists, our soil would never reach the level needed for foliar feeding to do any good.
Bonsai need nitrogen, phosphorus, and potassium the most, as do any other plants and these nutrients are the very ones that foliar feeding is the worst at providing.
It is my personal opinion that any success by bonsaists using foliar feeding can be directly attributed to the mixture running off onto the soil, not through absorption through the leaves. The common practice of watering from above and dosing the foliage puts the nutrients into the soil, even though the bonsaist believes they are foliar feeding."
I, as always, would welcome rebuttal that is based on at least the same quality references, sources, and research as presented. As always, I would love being proved wrong as much as I love being proved right, either way, our knowledge and understanding of the subject is increased. No matter the outcome of these debates, we all win.
Will