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. HOPKiNSCaFe, CuB, Mn, C.l. MoNiZnsky, Mgr
 

NUTRIENT MOBILITY
Two directions of movement in plants
1) acropetal - means towards the apex; transport up in the 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 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

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.

FERTILIZER RATIO

ratio - the relative proportion of N to P₂0₅ to K₂0 in a fertilizer.

USING FERTILIZER RATIOS TO MANIPULATE PLANT 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) 

• 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) 

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

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

C:N of Organic Matter 30:1 approx cut-off for net N release or depletion
Organic Matter	C:N	Effect on N
chicken manure	7:1	Low C:N Ratio Net nitrogen release into the soil Acts as an organic N fertilizer
bat guano	10:1
alfalfa fresh cut	12:1
mushroom compost	13:1
cow manure	15:1
grass clippings	20:1
horse manure	25:1
rye grass cover crop	26:1
leaves	60:1	High C:N Ratio Net nitrogen depletion Acts as a N un-fertilizer
pine needles	80:1
bark uncomposted	223:1
saw dust or wood chips	200-500:1