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