1. Plant Nutrients

2. Assessment of Nutrient Needs
Visual inspection of crops for deficiency symptoms
Damage could have occurred already
Symptoms may not be reliable
Soil tests to measure nutrient levels
Growers depend on this method to determine lime and fertilizer needs
Tissue testing for nutrients in plants
May uncover problems that soil test misses

3. Soil Testing Soil sampling Soil testing Soil Interpretation
Recommendation 37

4. to Help Make Good Decisions
Take a Good Soil Sample
to Help Make Good Decisions

5. Taking a Soil Sample Sampling Area Should not exceed 10 acres
For row crops
Sampling Depth
Conventional tillage: 6-9 inches
No till: Use special pH sample in
top 2”
Sod or pasture: 2-3 inches
Tree Crops: inches
Rotation field 1
Permanent
Pasture
Low
Spot
Rotation field 2 38

6. Soil Test Results pH: Acid, Neutral, Alkaline
Soil Test Rating: VL, L, M, H, VH, EH
(How much of a nutrient is available)
Soil Test Index: (How high or how low a nutrient is in the soil) 39

7. Soil Test Explanation Soil Test Rating Index
Very Low (H) Severe deficiency
Low (L) Moderate deficiency
Medium (M) Near optimum: some fertilizer recommended
High (H) Adequate for most crops
Very High (VH) Two to four times the amount considered
adequate; none should be applied
Extremely High (EH) Excessive; none should be applied
Phosphorus, Potassium, Magnesium, calcium 40

8. Additional Resources
(1) Nitrogen Fertilizer Recommendation for Corn in Iowa
(2) Iowa State University Soil Testing Lab
(3) Extension Publications.

9. Plant Food Elements Used in Large Amounts Macronutrients
Used in Small Amounts
Primary Nutrients
Secondary Nutrients
Micronutrients
Nitrogen (N)
Calcium (Ca)
Iron (Fe)
Phosphorus (P)
Magnesium (Mg)
Manganese (Mn)
Potassium (K)
Sulfur (S)
Zinc (Zn)
Copper (Cu)
Boron (Bo)
Chlorine (Cl)
Cobalt (Co) 34

10. Nitrogen Nitrogen is a primary component of proteins and is part of
every living cell.
Functions of Nitrogen
Speeds growth
Vigorous growth, large leaves, and long stem internodes.
Required for the formation of dark green pigment: chlorophyll.
Promotes better production of chlorophyll hence it is required
for better source of forage, feed and human nutrition.
Plants use water best when they have ample nitrogen. 35

11. Excess Nitrogen Soft, weak easily injured growth
Stems are weaker and more easily to lodge
Soft growth is more prone to diseases and insects
Overly rapid growth slows maturity and ripening of many
crops
N promotes vegetative rather than reproductive growth
of flowers and leaves.
Over-fertilized tomato plants promote lush growth
but few fruits

12. Nitrogen deficiency Slow growth and stunting
Plants lack dark green color of well fed plants: Chlorosis 36

13. Phosphorus
Functions
Phosphorus is part of chromosomes and genes and so it is
involved in plant reproduction and cell division.
P spurs early and rapid growth and helps a young plant
develop its roots
P helps plants resist cold and diseases
P speeds up crop maturity
P aids blooming and fruiting
P improves the quality of grains and fruits

14. Phosphorus Deficiency
There is stunted growth but plants could remain green.
Plants have a purple tint to leaves and stems, starting on lower
Older leaves

15. Potassium (Potash) Functions
Activates enzymes needed in the formation of protein, starch
cellulose and lignin.
It is important in the formation of thick cell walls and strong,
rigid plant stems.
Regulates the opening and closing of pores in the leaf through
which water, oxygen and carbon dioxide pass.
Important in the development and ripening of fruits like apples
or tomatoes
Needed for proper growth of root and tuber crops

16. Potassium Deficiencies
Seen less often than the other primary nutrients.
Shortages occur primarily in sandy heavily leached soils.
“Marginal scorch” or burnt edges of lower, older leaves

17. Secondary Nutrients Calcium Functions of Calcium
Required by plants mainly to build cell wall
Crispness of apples come from calcium pectate in the fruit cells
Ca largely controls soil pH and helps in the formation of soil
structure
Calcium plays a role in protein formation and carbohydrate
movement in plants

18. Calcium Deficiencies Commonly appear in fruits and vegetables.
Apple growers prevent “water core” (collapse of cell walls) in
apples by spraying trees with Ca.
This is similar to “blossom end rot” in tomatoes.
Soil dries out and slows movement of Ca to roots during rapid
root development.
Ca deficiency cause misshapen roots on root vegetables.

19. Magnesium Functions of Magnesium
It is an essential ingredient in chlorophyll formation
Each chlorophyll molecule has one magnesium atom at the center
Magnesium activates a number of important enzyme systems
Mg is involved in protein, carbohydrates and fat synthesis

20. Sulfur
Functions of Sulfur
Needed in the formation of proteins and chlorophyll
Aids in the formation of nodules in legumes and seed production
S improves stress tolerance.
Alfalfa, members of the mustard family and members of the onion
family need much sulfur.
The pungent flavors derive from sulfur compounds

21. Sulfur Deficiencies Stunted growth
Older leaves are pale green – similar to N-deficient plants

22. Micronutrients
These form special organic-metal molecules called Enzymes.
Enzymes activate biological reactions in living systems.
The difference between enough and too much can be quite
narrow, sometimes only a few pounds per acre
Please apply elements with caution

23. Effect of pH on nutrient availability

24. Iron
Functions of Iron
Iron is part of many enzymes necessary for the formation of
chlorophyll
It is an abundant element in rocks and soils but it is also one
of the most commonly deficient micronutrient

25. Symptoms of Iron Hunger
“Chlorosis”: Yellowing of interveinal leaves.
Mainly new leaves

26. Manganese Functions of Manganese
Speeds up germination and crop maturity
Helps uptake of several other nutrients
Functions in chlorophyll development

27. Symptoms of Manganese Deficiency
Dwarfing
Chlorosis on new leaves

28. Zinc Functions of Zinc Needed in the metabolism of protein
Involved somehow in the production of chlorophyll

29. Symptoms of Zinc Deficiency
Fruit crops including peaches and citrus are sensitive to zinc
deficiency
Field crops also include corn, soybeans, cotton, and potatoes
Symptoms include spots on leaves
Chlorosis between veins is also
common

31. Fertilizers Fertilizer Material Mixed fertilizer
Added to the soil to provide essential nutrients to plants
Fertilizer Material
Chemical compounds or mixtures
containing nutrient
Mixed fertilizer
Weed and Feed fertilizers
Liquid fertilizers
Fertilizer Spikes
Slow-release fertilizers 41

32. Fertilizer Grade: 13 - 13 - 13 %N % Potash K O 2 % Phosphate (P2 O 5 )42

33. Some Popular Fertilizer Grades Available in Alabama
Fertilizer Grade % of all Grades sold
in Alabama % % % % % %
(diammonium phosphate) 5% % % %
<18% 43

34. Examples of Fertilizer Calculations
Recommendation:
120 Ib N, 60Ib Phosphate, 60 Ibs potash per acre
Fertilizer Grade:
Before Planting
60/13% percent = 461 pounds / acre of
Amount needed
Analysis of source
Size of Garden : 50 x 20 = 1,000 square feet
1 acre = 43, 000 square feet
1,000 square feet = 1,000 / 43,000 = acres
Fertilizer needed = x 461 pounds per acre = 0.6 Ib 44

35. Examples of Fertilizer Calculations
Recommendation:
120 Ib N, 60Ib Phosphate, 60 Ibs potash per acre
Fertilizer Grade:
Sidedressing
Use ammonium nitrate ( )
Amount needed per acre = 60 / 34% = 176 pounds
Size of Garden = acres
Amount required for side dressing = x 176 = 4 pounds

36. “Per 50 ft x 20 ft garden apply 6 pounds of 8 - 8 - 8
Recommendation:
“Per 50 ft x 20 ft garden apply 6 pounds of
at planting and sidedress with 4 pounds of ”
Fertilizer Grade Available:
At Planting
6 Ib (expected) x 8 (required) / 13 (available ) = 3.7
Sidedressing
4 x 8 / 13 = 2.5 Ib, 46