What is an Iron Fertilizer?

Iron fertilizer is a type of plant fertilizer, which is most often used on golf course grasses and for plants growing in alkaline soils. Plants need iron in trace amounts in order to maintain green leaves, and iron fertilizer is used to make more iron accessible to plants when it is not readily available in the soil. It is also theorized that using iron fertilizer on ocean phytoplankton will help decrease global warming.

The majority of plant fertilizers provide nitrogen, phosphorous, or potassium, because plants obtain those nutrients from the soil in the greatest quantities. Plants receive many additional nutrients, such as iron, from soil in much smaller quantities. Lack of iron will cause a plant to have yellowed leaves.

In many places, there is enough iron present in soil to supply plants with their minimal needs. Alkaline soils, however, which are often found in arid climates, are acidic and tend to bind iron before plants can absorb the nutrient. Although some plants do well in alkaline soils, many plants suffer iron deficiencies. When this occurs, iron fertilizer is used.

In addition to providing iron to plants in alkaline soils, iron fertilizer is often used in areas where the grass must be brilliantly green. For example, golf courses often apply iron fertilizer to make sure the grass has as much iron as needed to maintain a lush green growth. Homeowners may also use iron fertilizer to obtain a more vibrant green for their yards.

There are two types of iron fertilizers: iron sulfate and chelated iron. Iron sulfate fertilizers are less expensive than their chelated counterparts, but chelated iron resists binding by the soil before the plants can absorb it. These fertilizers can also be obtained in liquid or granule form. Although liquid forms can stain paved areas, they generally provide plants with more easily obtainable iron.

Possibly the most interesting use of iron fertilizer is in global warming research. This research is based on the premise that carbon dioxide, CO₂, makes up much of the greenhouse gases contributing to global warming. Phytoplankton, algae which is abundant in areas of the open ocean, pulls carbon dioxide from the air and uses the carbon to build plant tissue. When the algae dies, it, and the carbon it contains, sinks to the bottom of the ocean, trapping the carbon and removing it semi-permanently from the atmosphere.

Researchers theorize that by providing the ocean's algae with iron fertilizer, more phytoplankton can grow and more carbon dioxide can be eliminated from the atmosphere. This idea comes from studies which show that algae live and grow until certain micronutrients, most often iron, are used up. Therefore, by increasing the iron available, researchers may increase the amount of carbon used by the plants, thus eliminating it from the atmosphere.