Anorganic Fertilizer

Lenny Sri Nopriani, SP.MP

Jargon

Fertilizer ≠ Synthetic

Fertilizers can be organic or inorganic

Organic: from living material, contains C-C bonds; does not imply organic certification (e.g. biosolids)

Inorganic: not from living material (e.g. rock phosphate) and/or manufactured/synthetic (e.g. anhydrous ammonia)

Soil Nutrients and Fertilizers

Macro vs Micro Nutrients

Macro nutrients are required by the plant in relatively large amounts

Micro nutrients are required only in small amounts

minor or trace elements

Macro nutrients

Non-mineral elements

carbon (C)

hydrogen (H)

oxygen (O)

Primary Nutrients

Nitrogen (N)

Phosphorus (P)

Potassium (K)

Secondary Nutrients

calcium (Ca)

magnesium (Mg)

sulfur (S)

Micro nutrients

Iron (Fe)

Copper (Cu)

Zinc (Zn)

Boron (B)

Molybdenum (Mo)

Manganese (Mn)

Chlorine (Cl)

Fertilizers

Types of Fertilizers

Complete

Incomplete

Organic

Inorganic

Soluble

Insoluble

Complete vs. Incomplete

Complete has all three primary nutrients-nitrogen phosphorous & potassium

Examples: 10-10-10, 15-30-15, 20-5-20

Incomplete DOES NOT have all three primary nutrients

Examples: 20-0-0, 0-20-0, 12-0-44

Organic Fertilizers

Comes from plant or animal matter and contains carbon compounds

Examples: urea, sludge and animal tankage

Advantages of Organic

Slow release of nutrients

Not easily leached from the soil

Add organic components to growing media

Disadvantages of Organic

Hard to get

Not sterile

Low nutrient content

Expensive

Inorganic Fertilizers

Comes from sources other than animals or plants

Chemical products

Advantages of Inorganic

Can make the desired ratio of nutrients

easy to get

lower cost

Disadvantages of Inorganic

No organic material

possible chemical building up in growing media

Soluble Fertilizer

Dissolve in water and are applied as a liquid solution

Fertigation

fertilizing through irrigation water

big advantage

Insoluble Fertilizer

Includes granular and slow release applied to the growing media

Granular vs. Slow Release

Granular

relatively inexpensive

easy to find

Slow Release

more expensive because it is coated

more uniform release of nutrients over time period

Fertilizer Analysis

Fertilizer analysis expresses weight as a percent of nitrogen, phosphorus and potassium

20-10-20

Fertilizer Analysis

For Example

A 100 Kg bag of fertilizer has an analysis of 15-5-15. How many pounds of nitrogen, phosphorus and potassium are in the bag?

Nitrogen: 100Kg X 15%=15Kg

Phosphorus: 100Kg X 5%=5Kg

Potassium: 100Kg X 15%=15Kg

Fertilizer Ratios

A fertilizer with a 10-10-10 analysis would have a 1:1:1 ratio

A fertilizer with a 24-8-16 analysis would have a 3:1:2 ratio

What would be the ratio for a fertilizer with an analysis of 36-18-27?

4:2:3

Inorganic Nitrogen Fertilizers

Created through Haber-Bosch process

Combine N2 and H2 under high temperature and pressure to create NH3 gas

Anhydrous ammonia will boil & volatilize under normal atmospheric conditions

Compression and refrigeration turn it to liquid

Applied by injection into to soil to minimize losses into the air

Benefits & Drawbacks

Very high concentration of N (82%)

Readily absorbed by human tissue— requires use of protective gear

Public safety—explosive & used in drug production

Toxic to microorganisms—will kill the bugs in your soil for a few weeks

Anhydrous Ammonia

Other Inorganic N Sources

Ammonium nitrate, sulfate, and phosphate are commonly used because they form soluble white crystalline solids that are easy to handle

Phosphorus

Main source is rock phosphate

Mined from ancient marine sediments that contain apatite—70% is from US & Asia

Minimal processing—– Beneficiation (remove clay, carbonate, or silica contents through sieving and flotation)– Grind finely

May treat with sulfuric acid to dissolve apatite, increase P solubility (creates superphosphate)

Rock Phosphate Mining in India

Forms of Inorganic Phosphorus

Potassium

Mined from sedimentary or salt lake deposits of KCl or K2SO4 (e.g. Utah & Dead Sea)

Separate K salts from Na salts

US imports 80% of its K fertilizers

Commonly available as: – KNO3(saltpeter)- KCl – K2O (potash)- K2SO4

Mining Potash in Utah

Sulfur

Usually applied as gypsum (CaSO4)

Source is sedimentary rocks

Minimal processing—soluble and good source of Ca and S with only grinding

Other applications include superphosphate (H2SO4) and elemental sulfur

Collecting Sulfur

Benefits and Drawbacks

Highly concentrated

Concentrations of nutrients are specific and predictable

Fast release

Can apply exactly what’s needed

Overdoing it may result in conditions toxic to plants and/or soil microbes (from nutrient ions or secondary ingredients)

Incomplete source of nutrients

Application Procedures

Banding

Sidedressing

Topdressing

Perforating

Broadcasting

Foliar spraying

Fertigation

Banding

Placing a band of fertilizer about two inches to the sides and about two inches below seed depth.

DO NOT place below the seeds because fertilizer will burn the roots.

Sidedressing

Placing a band of fertilizer near the soil surface and to the sides after seedlings emerge from the soil.

Topdressing

Mixing fertilizer uniformly into the top one to two inches of growing media around the plant.

Perforating

Placing fertilizer in 12”-18” holes drilled 18” to 24” around the canopy drip line of fruit trees. Cover the holes and fertilizer slowly dissolves.

Broadcasting

Spreading fertilizer to cover the entire production area

Foliar Spraying

Spraying micronutrients in a solution directly on plant leaves.

Quickly corrects nutrient deficiencies

Fertilizer concentration should not be too high or leaf burning will occur.

Fertigation

Incorporating water-soluble fertilizer into the irrigation system of greenhouse and nursery crops.

Concentrated solutions usually pass through proportioners or injectors to dilute to the correct ratio.

Venturi-type

Positive-displacement

Venturi-type

Simple and inexpensive

less accurate

depends on water pressure in the hose and in the smaller tube to proportion

Example: H ozon

Positive-displacement

More expensive

very accurate

physically inject and mix specific amounts of concentrated solution and water

Examples: commander proportioners, and Smith injectors

Rules for applying fertilizers

Method used should be practical, effective and cost efficient

Method used affects nutrient availability for plant use

Fertilizer must be dissolved and reach plant roots

Choose the Right One...

In order to pick a good fertilizer, ask yourself:

① Does it have the needed nutrients?

② Will it release them at the right time?

③ Is it affordable?

④ Is it convenient enough to use?

⑤ Are its side effects acceptable?