ESSENTIAL ELEMENTS, MOBILITY AND pH EFFECT

ESSENTIAL ELEMENTS, MOBILITY AND pH EFFECT

essential element - an element required by plants for normal growth, development and completion                                 of its life cycle, and which cannot be substituted for by other chemical                                 compounds.   17 ELEMENTS ARE REQUIRED BY PLANTS     3 supplied naturally by air and water - comprise the bulk of the plant        C, H, 0       6 macronutrients - required at 0.1 to 6% of the dry weight of plants        N, P, K, S, Ca, Mg      8 micronutrients - required at 1 to 300 ppm of the dry weight of plants        Fe, Zn, Cu, Mo, B, Mn, Cl, Ni         Cl and Ni are ubiquitous - hence, will not be addressed in detail    The essential elements can be easily remembered by a catch phrase such as    C. HOPKiNS CaFe, CuB, Mn, C.l. MoNiZnsky, Mgr       NUTRIENT MOBILITY   Two directions of movement in plants    1) acropetal - means towards the apex; transport up the in xylem    2) basipetal - means towards the base; transport down in the phloem    Two classifications of nutrient mobility    1) mobile - moves both up and down the plant by both acropetal and basipetal  transport (in both                     the xylem and the phloem).        Deficiency appears on older leaves first.        N, P, K, Mg, S      2) immobile -  moves up the plant by only acropetal (in the xylem) transport        Deficiency appears on new leaves first.        Ca, Fe, Zn, Mo, B, Cu, Mn       EFFECT OF pH     The pH determines solubility in the soil   1) more available at low pH (below 5.5), and less available at high pH.         Fe, Zn, Cu, Mn, B     2) more available at high pH (above 6.5), and less available at low pH.        N, K, Mg, Ca, S, Mo      3) more available at intermediate pH (6-7)          P       Ideal pH   slightly acid:    a) around 6.5 for field soil    b) around 5.5-6.0 for artificial growing media made with peat moss or composted bark

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FERTILIZER ANALYSIS AND RATIO

FERTILIZER ANALYSIS   analysis - sequence of 3 numbers on the fertilizer label that gives the percent composition of                   N-P205-K20 in a fertilizer; required by law to be on the label of every fertilizer sold.    Example: 8-8-8 means the fertilizer contains:    8% N    8% P205    8% K20    24% total nutrient content        Buy fertilizers by price per pound of fertilizer, not price per bag.    100 lb. of 8-8-8 @ $4.99 100 lb. @ 24% = 24 lb. of nutrients @ $4.99 = 20.8 cents per lb 100 lb. of 13-13-13 @ $5.99 100 lb @ 39% = 39 lb. of nutrients @ $5.99 = 15.3 cents per lb.     FERTILIZER RATIO    ratio - the relative proportion of N to P205 to K20 in a fertilizer. Analysis 8-8-8 20-20-20 10-20-10 18-6-12 Ratio 1-1-1 1-1-1 1-2-1 3-1-2      USING FERTILIZER RATIOS TO MANIPULATE GROWTH    a) to favor vegetative growth     use a high N, low P and K fertilizer  for example, use a 2-1-1 or 3-1-1 ratio fertilizer (higher 1st number)  b) to favor flowering, root and underground storage organ growth    use a low N, high P and/or K fertilizer  for example, use a 1-2-2 or 1-3-2 ratio fertilizer (higher 2nd and/or 3rd number)

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FUNCTION OF NUTRIENTS

Nutrient  Symbol Function nitrogen N 1) Component of chlorophyll; amino acids, proteins and enzymes;       nucleic acids (RNA and DNA); some auxins and cytokinins.  phosphorus P 1) Component of the high energy compounds ATP, NADPH and        NADP; nucleic acids (DNA and RNA); and phospholipids.  potassium K 1) Needed for protein and enzyme synthesis and activation.     2) Involved in maintaining proper water balance     3) Needed for photosynthesis.  magnesium Mg 1) Component of chlorophyll.     2) Activates many enzymes.  calcium Ca 1) Ca pectates in middle lamella of cell wall cement cells together.     2) Required for normal cell division and meristem growth.     3) Stabilizes membranes sulfur S 1) Component of several amino acids (methionine, cystine, cysteine). iron Fe 1) Required for chlorophyll synthesis.     2) Component of many enzymes and carriers, especially those of        electron transport chain. zinc Zn 1) Required for tryptophan, hence auxin (IAA), synthesis. manganese Mn 1) Required for chlorophyll synthesis.     2) Activates many enzymes. copper Cu 1) Required for chlorophyll synthesis.     2) Component of many enzymes and carriers, especially those of        electron transport chain. boron B 1) Required for complete flowering and fruit development.     2) Involved in translocation of carbohydrates and hormones.  molybdenum Mo 1) Component of enzymes in N metabolism (nitrate to organic N)     2) Component of enzymes in nitrogen fixation (N gas to ammonia) chlorine Cl 1) Oxygen evolution in photosynthesis     2) Stomatal functioning  nickel Ni 1) Component of several enzymes, especially urease (breaks down urea)

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TISSUE CONCENTRATION, DEFICIENCY SYMPTOMS AND FERTILIZER SOURCES

Nutrient Tissue Concentration Characteristic Deficiency Symptom* Fertilizer Sources    MACRONUTRIENTS N 2-6% older leaves - overall chlorosis NH4 nitrate, sulfate, phosphate;      K, Na, or Ca nitrate; urea  P 0.2-1.2% older leaves - deep green, purple coloration of petioles superphosphate; NH4 or K phosphate; phosphoric acid  K 1-6% (luxury consumption) older leaves - interveinal chlorosis with marginal and tip necrosis K nitrate, chloride, phosphate, or sulfate; K frit  Mg  0.2-1% older leaves - interveinal chlorosis and bronze coloration dolomite (Ca/Mg carbonate),    Mg sulfate (Epsom salt) Ca 0.5-2%  stem tips - die, small leaves limes (Ca carbonate/hydroxide);      Ca sulfate (gypsum) or nitrate;    superphosphate S 0.3-0.7% all leaves overall chlorosis, on young leaves 1st then progresses to old leaves sulfate carriers; elemental S;    air pollution; superphosphate    MICRONUTRIENTS**  Fe 50-300 ppm young leaves - severe interveinal chlorosis  Fe chelate; Fe sulfate; some pesticides  Zn 5-75 ppm new growth - rosetted growth & small leaves Zn chelate; Zn sulfate;      some pesticides Mn 30-300 ppm young leaves - interveinal chlorosis with necrosis when severe Mn chelate; Mn sulfate;    some pesticides Cu 5-30 ppm stem tips - die, stunted; leaves small; multiple buds formed Cu chelate; Cu sulfate;    some pesticides B 30-200 ppm stem tips - internodes short, thick; leaves thick, brittle, with necrosis borax; boric acid Mo 1 ppm similar to N deficiency, except occurs on young leaves. Na or NH4 molybdate  Cl & Ni ? virtually never seen in nature ubiquitous *chlorosis = yellowing;  necrosis = browning;  interveinal = between the veins   **micronutrients are often applied as a multi-micronutrient mix; ex. STEM, PERK, Micromax

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NUTRIENTS WITH SIMILAR DEFICIENCY SYMPTOMS

Nutrients That Cause Interveinal Chlorosis Deficiency Of  Interveinal Chlorosis Occurs On  With No Necrosis  Plus Necrosis Young Leaves Fe Mn Old Leaves Mg K

Nutrients That Cause Overall Chlorosis Overall Chlorosis Occurs on Deficiency Of Old Leaves N New Leaves Mo New Leaves, Then Spreading to Old Leaves S

Nutrients That Effect the Shoot Tip Various Deficiency Symptoms on Growing Point, Emerging Leaves or Shoot Tip  Deficiency Of Small New Leaves and Rosetted New Growth Zn Thick and Brittle New Leaves B New Leaves Distorted and Necrotic Ca Vague Symptoms: New Leaves Small, Wilted, Translucent or Necrotic Cu

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NITROGEN CYCLE

WAYS IN WHICH NITROGEN IS LOST FROM THE SOIL    1) leaching (especially nitrate which is negatively charged)    2) plant absorption    3) microorganisms consume (see C:N ratio next page)    4) denitrification

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NITROGEN CONVERSIONS

NITROGEN REACTIONS   mineralization or ammonification -the conversion of organic nitrogen (in the -NH2 form) to                                                          inorganic nitrogen (in the NH4 form).                                                        - the speed of conversion depends on the C:N ratio (see below).   nitrification - a two step process converting ammonium to nitrite, then nitrite to nitrate.                       - the soil bacterium Nitrosomonas converts ammonium to nitrite                      - the soil bacterium Nitrobacter converts nitrite to nitrate                      - this occurs very quickly so little ammonium (which can be toxic if high) and                        virtually no nitrite (which is highly toxic) accumulates in the soil.   denitrification - the conversion of nitrate in the soil to gaseous nitrogen that escapes into the                            atmosphere.    nitrogen fixation - the conversion of gaseous nitrogen to ammonia.                               - only nitrogen fixing microorganisms can cause nitrogen fixation;                                 some form symbiotic relationships with plants (see table below)      CARBON:NITROGEN (C:N) RATIOS IN ORGANIC MATTER   C:N Ratio - proportion  of carbon to nitrogen present in organic matter.    a) high C:N ratio - wood, sawdust, uncomposted bark        - microbes use up all nitrogen in organic matter when consuming carbon,       - then the microbes use up the nitrogen in the soil    b) low C:N ratio - manure, bone meal, fish emulsion, organic fertilizers        - microbes consume carbon,        - then release excess nitrogen from the organic matter into the soil       - thus, low C:N organic matter acts as an organic nitrogen fertilizer

MICROORGANISMS THAT CAN FIX NITROGEN   Type Microorganism Nitrogen-Fixing Microorganism Forms Symbiotic Relationship With 1) Bacteria  Rhizobium Legumes (soybean, clover, mesquite) 2) Bacteria Azotobacter Clostridium free living only 3) Filamentous Bacteria some Actinomycetes Some woody plants, (Alnus and Elaeagnus) 4) Blue-green algae   Anabaena Azolla and Cycads (can also be free living)