Soil Nutrients &
Fertilizers
Plant Nutrients
 Substances that are primary (macro) and
secondary requirements for growth and
development of plants.
 Macronutrient plants get from air and water:
 carbon, oxygen, hydrogen
 Macronutrients plants get from the soil:
 Nitrogen (N)
 Phosphorus (P)
 Potassium (K)
 Secondary Nutrients found in soil
 Calcium, Magnesium, Sulfur
Nitrogen (N)
 Most important nutrient
 Required for proper growth and green
color of stems and leaves
 Determines fruit size
 Comes from organic matter humus
(nitrogen cycle)
 Lack of nitrogen results in
 slow growth and yellow leaves
 Too much nitrogen
 creates weak stems and plants are
more susceptible to disease
 Too much nitrogen in food can
 cause nitrogen poisoning in animals
(cattle)
Leaf Lacking Nitrogen
Phosphorus (P)
 Necessary for root,
flower and seed
development
 Found only in certain
rocks and may
become limited
 Lack of phosphorus
causes slow growth
and purple leaves
Potassium (K)
 necessary for the
development of strong
stems and resistance to
disease
 needed for the development
and ripening of fruit
 found in many rocks so the
supply is less limited than
phosphorus
 lack of potassium causes
browning of leaf edges
pH
 The measure of acidity and alkalinity of a soil >
extremely important!
 If the pH is too acidic or basic for a plant,
nutrients will not be absorbed by the roots
 Most plants prefer 6.0 – 7.0
Fertilizer
 Any substance added to the soil
to supply plants with nutrients.
 Two types:
 Synthetic (man-made)
 Organic (found naturally)
So now you’re a farmer…
 How do you use N-P-K values to fertilize your crops?
 Look up fertilizers and how you might “pick” the right fertilizer
based on NPK of the bag…what do the NPK values mean?
 On your farms, you notice you have slightly purple leaves on
your corn, VERY small sized fruit and it takes a VERY long time
for your fruit to ripen. Find me a fertilizer that will work for your
farm to maybe solve your problems.
Each has their advantages
 List Advantages and Disadvantages of
each from page 244-247 (worksheet
table)