What Breaks Down Fertilizer?

Temperature

• Fertilizers are made up of a variety of chemicals and nutrients that supply plants with nitrogen, phosphorous and potassium -- three of the macronutrients essential to healthy plant life. Urea is a manufactured ingredient found in a variety of fertilizers. Warm weather is instrumental in breaking down urea. As urea breaks down it releases nitrates that encourage shoot and foliar growth.

  Nitrogen fertilizers are usually applied to lawns during the fall. The fertilizer is relatively inactive, but once temperatures begin to warm, the nitrogen becomes available to the lawn just as the initial growth flush begins. Warm soils, those within the 60 degree Fahrenheit range, also hold active organisms which further help break down nitrogen.

Irrigation

• Some fertilizers are water soluble. They are applied via foliar spray directly onto the plant's foliage and roots. These fertilizers will not break down unless they are diluted. Foliar sprays contain essential micronutrients like iron and zinc. They also provide phosphorous and potassium, elements that are essential for shoot and root development. Foliar fertilizers break down rapidly because their nutrients are absorbed through plant leaves. Plants take in the nutrients and break them down. These types of fertilizers are useful in situations where the ground is still cool and unable to break down traditional fertilizers. Granular fertilizers, as well as composts and other amendments, also require moist mediums to facilitate the chemical reactions that are responsible for nutrient breakdown and uptake.

Microorganisms

• Soil is replete with microorganisms. These creatures are responsible for cycling minerals and nutrients. Many fertilizers contain substances rich in nitrogen, phosphorous and potassium but the nutrients are "locked" within the substance. Only when microorganisms digest and process the materials are these nutrients released into the soil in a form capable of being taken in by plants. Fungi, bacteria, protozoa and algae ingest fertilizers and also enrich soils in organic matter. Larger organisms, like nematodes and earthworms, till soil as well as ingest fertilizers. By tilling soil they aid in air circulation. Oxygen aids in breaking down fertilizers. In anaerobic conditions, fertilizers, especially those high in organic matter, will not decompose. This leads to poor soil conditions and sulfuric odors.

Slow-release Fertilizers

• Synthetic fertilizers break down rapidly when soil conditions are warm and moist. Non-synthetic, organic and inorganic fertilizers release nutrients slowly and are highly dependent upon microorganisms for decomposition. Blood meal is an organic fertilizer that supplies nitrogen. Bone meal is high in phosphorous and cotton meal breaks down quickly in soil, which is advantageous early in a growing season. Other substances, like manure, must be aged prior to being interred in a garden. Aged manure releases nitrogen and other nutrients slowly. It may take an entire growing season for this fertilizer to break down.