Fertilizer Materials and Soil Nutrient Amendment

Plant nutrients are available throught root absorption of ions from soil solution.  Molecules in solution also can be absorbed by roots in some cases.  Thus, a fertilizer must first be dissolved to be used by plants.  Fertilizers are categorized as organic or inorganic.  Inorganic fertilizers are generally composed of simple, mostly water-soluble nutrient salts in granular, slow release or liquid formulations.  A fertilizer qualifies as naturally organic if derived from plant or animal materials or naturally occurring rocks and minerals containing one or more mineral elements that are essential for plant growth.  

The relative content of chemical elements nitrogen (N), phosphorus (P), and potassium (K) commonly used in fertilizers is labeled using NPK rating and any additional chemical labeling follows after that.  The N value is the percentage of elemental nitrogen by weight in the fertilizer.  The values for P and K represent an expression of these elements as oxides in the form of P2O5 and K2O.  This usage derives from the traditional practices of reporting elements as oxides.  

Materials may be used alone or blended with other fertilizers to form a multiple-nutrient fertilizer.  Generally there is no measurable difference in crop response to multiple-nutrient or single-nutrient fertilizers, as long as they supply the same amount of soluble nutrients.  The advantage of multiple-nutrient fertilizers over single-nutrient fertilizers is that only on fertilizer would be needed to supply several elements, rather than having to purchase several fertilizers.  The following tables are quick reference quides to various fertilizer materials that could be used to address soil nutrient defficiencies.  The actual nutrient content may vary from this list depending on the manufacturer and other materials blended with the product. Most values are for the fertilizer-grade product and not the pure chemical.  The chemical formulas are the primary active compound.  

Also included is the fertilizer liming and soil acidifying effect.  Pure calcium carbonate (CaCO3) is considered as the most commonly used liming material (lime) and is assigned a 100% neutralizing effect index also known as calcium carbonate equivalency (CCE).  The effectiveness of a liming matieral is based on the CCE scale where if greater than 100, the material is considered capable of neutralizing more acidity on a weight basis than pure CaCO3.

At the end of the tables there is an explanation with examples on how to calculate the amount of fertilizer to apply to meet agronomic nutrient requirements.  

Table 1: Primary and Secondary Nutrient Sources

E (Percentage)

Nitrogen Sources
Material N P2O5 K2O Ca Mg S †CCE/100 lbs
Ammonium nitrate 34 0 0 0 0 0 -61
Anhydrous ammonium 82 0 0 0 0 0 -148
Ammonium nitrate sulfate 30 0 0 0 0 5 -71
Calcium ammonium nitrate 27 0 0 6 0 0 0
Ammonium nitrate limestone 20 0 0 6 4 0 0
Ammonium sulfate 21 0 0 0 0 24 -110
Aqua ammonium 16-25 0 0 0 0 0 -45
Calcium nitrate/urea (Calurea) 34 0 0 10 0 0 -36
Calcium nitrate 15 0 0 21 0 0 +20
Crotonylidene diurea 32 0 0 0 0 0 none
Isobutylidene diurea 31 0 0 0 0 0 none
Nitrogen solutions (N-SOL or UAN sol (urea/ammonium nitrate):              
    32% UAN (35% urea + 45% A.N.) 32 0 0 0 0 0 -55
    30% UAN (33% urea + 42% A.N.) 30 0 0 0 0 0 -52
    28% UAN (30% urea + 40% A.N.) 28 0 0 0 0 0 -49
    21% AN (60% A.N. + 40% water) 21 0 0 0 0 0 -37
    19% AN (54% A.N. + 46% water) 19 0 0 0 0 0 -33
Potassium nitrate 13 0 44 0 0 0 +26
Sodium nitrate (nitrate of soda) 16 0 0 0 0 0 +29
Urea (sulfur coated) 36-38 0 0 0 0 0 -118
Urea 45 0 0 0 0 0 -81
Ureaform 38 0 0 0 0 0 -68
Phosphorous Sources
Material N P2O5 K2O Ca Mg S CCE/100 lbs
Ammoniated superphosphate 12-17 22-35 0 0 0 0 -7
Ammonium polyphosphate 10 34 0 0 0 0  
Diammonium phosphate (DAP) 18 46 0 0 0 0 -70
Ammonium phosphate nitrate 30 10 0 0 0 0 -54
Monoammonium phosphate (MAP) 11 48 0 1 0 0 -65
Ammonium phosphate sulfate 16 20 0 0 0 15 -80
Basic Slag 0 0-6 0 3-29 0 0 +70
Bone meal 0-2 10-20 0 19-25 0 0 +20
Concentrated superphosphate 0 46 0 14 0 2 0
Nitric phosphate 12-17 22-35 0 0 0 0 -20
Phosphate rock 0 2-35 0 0 0 0 +10
Normal superphosphate 0 20 0 21 0 11 0
Phosphoric acid 0 2-35 0 0 0 0  
    Conc. Wet-process acid 0 40-54 0 0 0 0 -90
    Wet-process acid 0 30 0 0 0 0 -63
    Superphosphoric acid 0 76 0 0 0 0 -110
Urea-ammonium phosphate 25 35 0 0 0 0  
Urea phosphate 17 44 0 0 0 0 -82
Potassium Sources
Material N P2O5 K2O Ca Mg S CCE/100 lbs
Greensand 0 1 6 0 0 0  
Potassium Carbonate Solid 0 0 48 0 0 0 +70
Liquid 0 0 34 0 0 0 +50
Potassium chloride 0 0 60 0 0 0 0
Potassium magnesium sulfate 0 0 21 0 11 23 0
Potassium metaphosphate 0 059 39 0 0    
Potassium nitrate 13 0 44 0 11 23 +26
Potassium sulfate 0 0 52 0 0 16 0
Calcium Sources
Material N P2O5 K2O Ca Mg S CCE/100 lbs
Calcium chloride 0 0 0 36 0 0 0  
Calcitic limestone (ground) 0 0 0 36 0 0 +98  
Burned Lime 0 0 0 70 0 0 +178  
Dolomitic limestone (ground) 0 0 0 24-30 6-12 0 +100  
Gypsum 0 0 0 22 0 18 0  
Selma chalk 0 0 0 32 0 0 +80  
Hydrated lime   0 0 0 50 0 0 +134
Magnesium Sources
Material N P2O5 K2O Ca Mg S CCE/100 lbs
Dolomotic limestone (ground) 0 0 0 24-30 6-12 0 +100
Magnesium oxide 0 0 0 0 45 0 +250
Magnesium ammonium phosphate 8 40 0 0 15 0  
Magnesium sulfate (Kieserite) 0 0 0 0 17 23 0
Magnesium sulfate (Epsom salt) 0 0 0 0 10 13 0
Potassium Magnesium sulfate 0 0 21 0 11 23 0
Sulfur Sources
Material N P2O5 K2O Ca Mg S CCE/100 lbs
Ammonium thiosulfate 12 0 0 0 0 26  
Ammonium sulfate 21 0 0 0 0 24 -110
Elemental sulfur Wettable S 0 0 0 0 0 95 -312
Flowable S 0 0 0 0 0 60 -218
Flowers of S 0 0 0 0 0 95 -312
Potassium sulfate 0 0 52 0 0 16 0
Potassium Magnesium sulfate 0 0 21 0 11 23 0
Gypsum 0 0 0 22 0 18 0
Magnesium sulfate (Epsom) 0 0 0 0 10 13 0
Sulfuric acid 0 0 0 0 0 20-26 -70

† CCE = Approximate calcium carbonate equivalence; Negative value indicates net acidifying effect on soil; positive value indicates net basic reaction in soil (AOAC).

Symbol key: N = Nitrogen; P2O5 = Phosphate; K2O = Potash; Ca = Calcium; Mg = Magnesium; S = Sulfur; CaCO3 = Calcitic Limestone 

Table 2.: Micronutrients Sources

Copper (Cu)
Materials Nutrient Content
Chelated Cu  
    Cu EDTA 13% Cu
    Cu HEDTA 9% Cu
Cupric ammonium phosphate 30% Cu
Copper oxide 60-80% Cu
Copper sulfate 35% Cu
Boron (B)
Materials Nutrient Content
Fertilizer borate  
    Borate granular                              14% B
    Borate 48 (i.e., 48 % B203)          15% B
Borax 11% B
Boric acid 17% B
Sodium borosilicate 6% B
Calcium borate 10% B
Solubor 20% B
Magnesium borate (boracite)                 21% B
Iron (Fe)
Materials Nutrient Content
Basic Slag 10-13% Fe
Ferric sulfate 20% Fe
Ferrous ammonium phosphate 29% Fe
Ferrous ammonium sulfate 14% Fe
Ferrous carbonate 42% Fe
Ferrous sulfate 20% Fe
Ferrous oxalate 30% Fe
Magnesium borate (boracite) 21% B
Zinc (Zn)
Materials Nutrient Content
Chelated Zn 9-14% Zn
Zinc sulfate 22-36% Zn
Zinc ammonium phosphate 34% Zn
Zinc oxide 78-80% Zn
Zinc sulfide 61% Zn
Zinc polyflavonoid 7-10% Zn
Manganese (Mn)
Materials Nutrient Content
Manganese oxide 68-70% Mn
Basic slag 1-3% Mn
Manganese carbonate 31% Mn
Manganese sulfate 24% Mn
Manganese chloride 17% Mn
Manganese ammonium phosphate 28% Mn
Molybdenum (Mo)
Materials Nutrient Content
Sodium molybdate 38-46% Mo
Impurities in superphosphate trace
Molybdenum frits 30% Mo

Table 3: Organic2 Fertilizer Materials

(Approximate Percent Values)

Material N P2O5 K2O Ca Mg S Micro-nutrients
Manure: (dried)              
Horse 0.4 0.2 0.3 * * * *
Cattle 1.5 1.5 1.2 1.1 0.3 * *
Poultry              
    Broiler litter 3.0 3.0 2.0 1.8 0.4 0.3 *
    Hen-caged layers 1.5 1.3 0.5 6 0.4 0.3 *
    Hen-litter 1.8 2.8 1.4 * * * *
Swine 0.6 0.4 0.1 * * * *
Sheep 0.6 0.3 0.2 * * * *
Blood (dried) 12-15 3.0 1.0 * * * *
Bone meal (steamed) 0.2 10-20 0 19-25 0 0 *
Blood meal 15 1.0 1.0 * * * *
Compost (garden) § 1 1 1 * * * *
Cottonseed hull ash 0 27 * * * * *
Cottonseed meal 6-7 2.5 1.5 * * * *
Cotton motes (composted gin wastes) 2 0.5 3 4 0.7 0.6 *
Fish scrap              
    (acidulated) 7-10 1-2 0 * * 2 *
    (dried fish meal) 9 3 6 * * * *
Hay:              
Legume 3.0 1.0 2.4 1.2 0.2 0.3 *
Peat / muck 2.3 0.5 0.7 * * * *
Sawdust 0.2 0 0.2 * * * *
Seaweed (dried) 0.7 0.8 5.0 * * * *
Sewage sludge (dried, municipal) 5 6 0.5 3 1 1 *
Tankage 7 10 7 * * * *
3Wood ashes 0 2 6 20 1 * *

Symbols: N = Nitrogen; P2O5 = Phosphorus; K2O = Potassium; Ca = Calcium; Mg = Magnesium; S = Sulfur

* - Unknown amounts

§ - Depends on raw materials and amendments composition

2 - Note: Organically Certified fertilizers are different from “naturally organic” http://www.omri.org/simple-opl-search/results/fertilizer

3 - Contains > 70% CaCO3 equivalent

Appendix

Appendix 1. Fertilizer Rates Calculations

Before using any fertilizers, it is important to understand how to read a fertilizer label. All fertilizers are labeled with %N - % P2O5 - %K2O by weight.

Example: 80 pounds of Potassium nitrate (13-0-44) would contain 10.4 pounds of N (80 X 0.13), 0 pounds of P2O5 (80 X 0), and 35.2 pounds of K2O (80 X 0.44).

Appendix 2. Amount of solid fertilizer to apply for a specific amount of nutrient

The basic formula for calculating how much fertilizer to apply to a given area for a specific amount of nutrient is:

Pounds of Fertilizer = (Pounds of nutrient needed) / (% nutrient in the fertilizer)

Examples:

  1. How much Potassium nitrate (13-0-44) is needed to apply 80 pounds of potassium (K)?
    It would take 182 pounds (80 ÷ 0.44) of Potassium nitrate to apply 80 pounds of K2O.
  2. What if Potassium chloride (0-0-60) was used instead?
    It would take 133 pounds (80 ÷ 0.60) of Potassium chloride to apply 80 pounds of K2O

Appendix 3. Amount of liquid fertilizer to apply for a specific amount of nutrient

The basic calculation formula for liquid fertilizers is similar to solids, but the density of the liquid fertilizer must be known before calculating the amount of fertilizer to apply.

Example:

How much N, P2O5, and K2O is in a 5 gallon jug of a 9-18-6 liquid fertilizer weighing 11.1 pounds per gallon?

Steps:

  1. How much fertilizer is present in the 5 gallons?
    There would be 55.5 pounds of fertilizer (11.1 lb/gal X 5 gal)
  2. What is the amount of each of N, P2O5, and K2O in the jug?
    There would be:
    5 pounds of N (55.5 X 0.09)
    10 pounds of P2O5 (55.5 X 0.18)
    and 3.3 pounds of K2O (55.5 X 0.06)