The majority of nitrogen-supplying organic fertilizers contain insoluble
nitrogen and act as a slow-release fertilizer. By their nature, organic
fertilizers increase physical and biological nutrient storage mechanisms
in soils, mitigating risks of over-fertilization. Organic fertilizer nutrient
content, solubility, and nutrient release rates are typically much lower than
mineral (inorganic) fertilizers. A University of North Carolina study found that
potential mineralizable nitrogen (PMN) in the soil was 182–285% higher
in organic mulched systems than in the synthetics control. Organic fertilizers
also re-emphasize the role of humus and other organic components of soil,
which are believed to play several important roles:Mobilizing existing soil
nutrients, so that good growth is achieved with lower nutrient densities while
wasting less Releasing nutrients at a slower, more consistent rate, helping to
avoid a boom-and-bust pattern Helping to retain soil moisture, reducing the
stress due to temporary moisture stress Improving the soil structure Helping
to prevent topsoil erosion (responsible for desertfication and the Dust bowl
Organic fertilizers also have the advantage of avoiding certain problems
associated with the regular heavy use of artificial fertilizers:The necessity
of reapplying artificial fertilizers regularly (and perhaps in increasing quantities)
to maintain fertility Extensive runoff of soluble nitrogen and phosphorus,
citation needed] leading to eutrophication of bodies of water (which causes
fish kills) Costs are lower for if fertilizer is locally available
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