Originally Posted by Kiril
Can someone tell me why a visual response is required for a plant to put an applied nutrient to beneficial use?
I have posted this several times over the years. It might not be 100% actuate but it is close and IMHO is still very valuable. It also answers your question.
Below is a Copy & paste from my website. It is COPYRIGHTED Copyright (C) 2001 by Ric all rights reserved. There are 17 elements essential to plant growth. They include Oxygen, Hydrogen, Carbon and the 13 listed below. Now for the $ 0.05 question which element did I not list and Why??
Nitrogen, N, causes cell elongation and division (growth). It is important for the development of all tissue in a plant, but it is most important for leaf growth Nitrogen fully translocates systemically within the plant and leaches readily from the soil. Pound for pound it is one of the cheapest fertilizer chemicals to produce and shows the greatest response (green) in plants. For this reason fertilizer manufacturers overuse this product.
Nitrogen Deficiencies, cause reduced growth rate of the entire plant, then loss of color on the older leaves. Then older leaves turn yellow and a general decline occurs on the entire plant.
Phosphorus, P, is important in root development, flowering, fruiting, and germination. Phosphorus fully translocates systemically within the plant and is subject to leaching in the soil depending on its form. The Jacksonville area of Florida. has a problem with phosphorus contamination. Our area is rich in phosphorus and it has been mined here since the 1890s to the present. Most fertilizer blends sold in our area are low in phosphorus. The need for high phosphorus blend fertilizer is new sod, sod plugs, gardenias, and bird of paradise plants.
Phosphorus Deficiencies, cause purpling of lower leaves first, then move on up the plant and reduce flower production.
Potassium, K, develops vascular flow, which is important for flowering, stem strength, vigor, disease resistance and overall hardiness. Its most important contribution is root development for drought stress resistance. Potassium fully translocates systemically in the plant. Potassium leaches readily from the soil. I personally like to use potassium on a one to one ratio with nitrogen even though it is a more expensive fertilizer.
Potassium Deficiencies, first cause yellowing between veins of older leaves, then yellow specks in the veins. Leaves finally turn brown on the outside margin.
Calcium, Ca, is essential for plant strength. Calcium does not translocate within a plant, nor does it leach from the soil. Luckily our soil has more than its share of calcium. Calcium nitrite is the cure for weak flushes of growth and fruit rotting at blossom end. It helps high traffic area turf.
Calcium Deficiencies, cause weak stem growth or growth of soft leaves.
Sulfur, S. functions with nitrogen to produce growth and photosynthesis. Sulfur compounds helps to reduce pH. Acid forming fertilizers are important in our area and use sulfur or sulfur combined material. The label on fertilizer will state whether sulfur is free or combined. Sulfur does not translocate in the plant but does leach out of the soil.
Sulfur Deficiencies, first cause yellowing on new growth then the entire plants slows its growth. Finally the plant goes into decline. If you have ever put fertilizer on turf and had areas grow but turn yellow, you have seen what a sulfur deficiency can do. Sometimes if we leave these areas alone they green up. The reason is that nitrogen breaks down in the soil first and is in useable form before sulfur.
Magnesium, Mg. Commonly available as Epson's salt is more important in maintaining green on older leaves but also helps new tissue. It helps in photosynthesis and helps to green up plants. Magnesium is mobile in the plant or translocates. It also readily leaches from the soil I have personally found it to make strawberries sweeter but cannot prove that.
Magnesium Deficiencies, cause older leaves to show yellowing between the veins. It looks like yellow triangles if you step back. On palm trees older fronds will yellow or brown early. Palm trees that have long ground sweeping green fronds do not have Magnesium or Manganese deficiencies.
Iron, Fe. Plays a major role in photosynthesis and helps keep our plants green. Iron does not translocate in the plant. Iron will become soil bound in high pH soils and unavailable to the plant. Iron does not leach from the soil.
Iron Deficiencies, first signs are lack of dark green color on new leaves. Lack of iron causes yellowing between veins of the newest leaves first, and the green veins appear narrow. Soils with pH of 6.5 or higher lock up iron and it is unavailable to the plant.
Manganese, Mn. is used in photosynthesis and helps to keep our plants green. It is essential for new tissue development. It does not translocate in the plant and is stable in the soil. It does not leach.
Manganese Deficiencies, also cause yellowing between the veins of new leafs. Veins appear wider than iron deficiencies. On palm trees frizzle top or yellowing on new fronds is the result of Manganese deficiencies.
Boron, B, is essential to development of new tissues. It does not translocate in the plant. and does not readily leach from the soil.
Boron Deficiencies, cause interveinal or tip and marginal yellowing on new leaves as well as distorted and brittle, small leathery leaves.
Copper, Cu. is essential to development of new tissues. It does not translocate in the plant and it does not readily leach from the soil.
Copper Deficiencies, cause young leaves to become cupped, wrinkled or roughened. New leaves yellow overall or between veins and tip burn can be present. New twigs die back.
Zinc, Zn. is essential to development of new tissue. It does not trans-locate in the plant and it does not readily leach from the soil. Yes, this is word for word the same as B Cu and Mo.
Zinc Deficiencies, cause yellowing between veins on newest leaves first. New growth is tiny pointed narrow leaves.
Molybdenum, Mo. is essential for development of new tissue. It does not translocate in the plant and it does not readily leach from the soil.
Molybdenum Deficiencies, lead to distorted new leaves and stems. B., Cu., Zn., and Mo. all show the same or similar signs of deficiencies. These elements are generally sold as a minor element package, either liquid, water soluble power or granular. It is not important to know which element is deficient. Only to, treat the signs with minor elements.
Chlorine Cl. has only recently been found to be essential for plant life. Its primary function and how it works is not known. So we do not know what the signs of a deficiency are. Chlorine is a byproduct of the chemical manufacturing of fertilizer. Too much chlorine can poison the soil and burn plants. If you ever spill swimming pool chlorine on your yard you will see this for yourself. If you do not treat this with gypsum it might be a long time before you have grass. The lower the percent of chlorine in a bag of fertilizer, the better.
it is one thing to do a off label applications. It is total stupidity to post it on the world wide web and expect people to approve.
You can lead a Donkey to water but you can't make the Jackass Drink