Tree Fruit Soils and Nutrition


13 Essential Nutrients

Primary Nutrients

Nitrogen (N)
Phosphorus (P)
Potassium (K)


Zinc (Zn)
Iron (Fe)
Copper (Cu)
Manganese (Mn)
Boron (B)
Molybdenum (Mo)
Chlorine (Cl)

Secondary Nutrients

Sulfur (S)
Calcium (Ca)
Magnesium (Mg)

Trick to remember nutrients:

“See (C) HOPKiNS (name) CaFe Managed By Mine CuZins, Mo and Claude”
C H O P K N S CaFe Mg B Mn CuZn Mo Cl

Plants receive Carbon, Hydrogen and Oxygen from water and air.

Nutrient Deficiencies

  • N, P, and K are required in the largest amounts and are commonly deficient (especially, N)
  • Deficiency symptoms for any element depend primarily on two factors:
    – the functions of the element
    – whether or not the element is readily translocated from older leaves to younger leaves

Nutrient Toxicities

  • Nutrients applied as a result of over fertilization or at the wrong time can have deleterious affects on plant growth.
  • Want to balance fertilizer application with plant needs and environmental concerns
  • Excess N, for example, can harm plants and contaminate surface and ground water possibly making drinking water unsafe.

Types of Fertilizers

  • Organic: natural materials with little to no processing
  • Processed fertilizers: manufactured or extracted from natural materials often undergoes extensive processing
  • Organic fertilizers usually release nutrients slower than processed forms
  • Nutrient content in organic products is typically lower than processed forms

Reading a Fertilizer Label

Fertilizer is usually labeled with just numbers such as 5-10-10. This always refers to the amount of N, P, and K, respectively. Therefore, it contains 5% N, 10% P (as P2O5), and 10% K (as K2O).

P is expressed as phosphate P2O5. Conversion is 1 lb P = 2.3 lb P2O5

K is expressed as K2O. Conversion is 1 lb K = 1.2 lb K2O


Common Processed Fertilizers
– Urea (46-0-0)
– Ammonium sulfate
– Ammonium nitrate (33-0-0)
– Calcium nitrate (15-0-0)
– Sulfur-coated urea
Phosphorus and Potassium
– Triple superphosphate
– Monoammonium phosphate (11-52-0)
– Potassium chloride
– Potassium magnesium sulfate (0-0-22-18S)

Unblended organic sources

    From “Fertilizing Your Garden”,
  1. Wood ash: good K source and may increase pH
    (1 cord of oak ash meets K needs of 4200ft2 and Douglas-fir ash good for 900 ft2)
  2. Grass clippings: good source of K; avoid weedy lawns (6- to 8-inch layer)
  3. Manure: improves structure and WHC; variable N contents; avoid fresh manure in veggie gardens
  4. Blood meal: good source of N (1.5-2 lbs per 100ft2)

Common forms of N for garden management


Form of nitrogen Source Availablity to plants Remarks
Organic nitrogen
(Proteins, amino acids)
• Animal manure
• Compost
• Plant residues
• Blood meal
• Many others
Not available until broken down--weeks to years Immobile in soil. Slowly converted to NH4+ in soil.
Urea • Commercial fertilizer
• Fresh manure
Available fairly quickly as ammonium.* Rapidly converted to NH4+ in soil.
Ammonium (NH4+) • Chemical fertilizers such as ammonium nitrate & ammonium sulfate
• Fresh manure
• Breakdown of organic matter in soil
Used directly by some plants; more so under acidic conditions.* Can adsorb to clay or organic matter, reducing leaching. Converted to NO3- by soil organisms.
Nitrate (NO3-) • Chemical fertilizers such as ammonium nitrate & potassium nitrate Used directly by most plants.* Highly mobile in water. Easily leached to ground-water.
Nitrogen gas (N2) • About 80% of air within soil spaces Only available to plants with nitrogen-fixing bacteria, such as legumes. Organic nitrogen and NH4+ are added to soil from legumes.
*Slow-release formulations are available that prolong availability to plants.


Eastern WA Fertilizer Formulas

Per 100 ft.2 garden, general N recommendations:

  • Vegetables and flowers: 1 lb N
    – (ex. apply 5 lbs ammonium sulfate or 3 lbs ammonium nitrate).
  • Woody plants: more vigorous growth, apply _ lb N.
  • If plants are as large as desirable and have healthy-looking foliage, fertilizer is not necessary.

Soil Tests

  • Can confirm whether a nutrient or amendment needs to be applied
  • Take a representative sample by compositing 10 samples at the 0-6in depth, mix, and subsample.
  • Use stainless steel or plastic tools
  • Label and transport or ship to lab ASAP


Next page:gardening on lead and arsenic soils



Updated July 15, 2004


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