A Simple Comparison

What is our cost per acre of equivalent commercial fertilizer plant nutrient? Most fertilizer dealers carry either DAP (18-46-0) or MAP (11-52-0). If we used MAP as an example, it has 11% N and 52% P205. Cost of potash (0-0-60) is $590 per ton.  The following is the basic cost comparison:

Organic Soil Amendment Cost per Acre: $501

Amendment Supplier Cost per Unit Application Rate Cost per Acre
Aragonite Fertrell $440.00 per ton 660 pounds per acre $145
Gold Super Starter, 2-4-2 Fertrell $17 for #50 bag 220 pounds per acre $85
Super K, 3-4-7 Fertrell $18.35 for #50 bag 440 pounds per acre $165
Off-Farm Bulk Manure Compost Moon’s Farm Yard, Ulysses, PA $26.60 per ton 4 ton per acre $106

Commercial Fertilizer Cost per Acre: $331

Amendment Supplier Cost per Unit Application Rate Cost per Acre
Dolomitic Lime Cornell Brothers, Middlebury Center, PA $53.95 per ton 2 ton per acre $107
MAP (11-52-0) Cornell Brothers, Middlebury Center, PA $527 per ton 509 pounds per acre $134
Potash (0-0-60) Cornell Brothers, Middlebury Center, PA $590 per ton 275 pounds per acre $81
Ammonium Sulfate (21-0-0-24S) Cornell Brothers, Middlebury Center, PA $150 per ton 120 pounds per acre $9

Commercial fertilizer cost would be $331/acre which is about one-half of the cost of the equivalent organic cost. Using only cost as the determining factor have led many farmers to the use of commercial fertilizer instead of organic practices.

Before making a fertilizing choice, consider the following important soil care considerations. What are commercial fertilizers and what happens to them after application and what about future soil care costs? Here are the some basic things to consider [1] .

Monoammonium Phosphate (MAP) is formed when a solution of phosphoric acid is added to ammonia until the solution is distinctly acidic. Monoammonium phosphate is often used in the blending of dry agricultural fertilizers. It supplies soil with the elements nitrogen and phosphorus in a form which is usable by plants. Diammonium Phosphate (DAP) is one of a series of water-soluble ammonium phosphate salts which can be produced when ammonia reacts with phosphoric acid. Potash is the common name for various mined and manufactured salts that contain potassium in water-soluble form. In some rare cases, potash can be formed with traces of organic materials such as plant remains. Ammonium sulfate is an inorganic salt commonly used as a soil fertilizer. It contains 21% nitrogen as ammonium cations, and 24% sulfur as sulfate anions.

Organic fertilizers are naturally occurring fertilizers (e.g. compost, manure), or naturally occurring mineral deposits (e.g. Rock phosphate, Green Potash derived from kelp, Jersey Greensand for trace minerals). Some “Processed” organic fertilizers include blood meal, bone meal, feather meal, and seaweed extracts.

Commercial fertilizers are highly soluble making them immediately available to the feeder roots of the plants. For the same reason, these chemical salts quickly leach out of the soil into groundwater. Also, these chemical salts have negative effects on the topsoil foodweb leading to a steady degrading of the soil season after season. Organic fertilizers give up their mineral content slowly and steadily rather than in a single, highly soluble burst. As a result, they do no harm to soil life, and do not leach out into the groundwater.

In the long-term, organic is clearly the better choice. In future planting years, commercial fertilizers will need to be re-applied at the above rates. The initial organic fertilizer application will continue to be available to plants for many years to come. Over time, smaller organic fertilizer application amounts will be needed to achieve the desired soil fertility. Therefore, it is easy to conclude that organic is the more cost-effective choice.

[1] From Wikipedia, the free encyclopedia

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Garlic Farmer
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