Organic fertilizer

Naturally occurring organic fertilizers include manure, slurry, worm castings, peat, seaweed, sewage, and guano. Green manure crops are also grown to add nutrients to the soil. Naturally occurring minerals such as mine rock phosphate, sulfate of potash and limestone are also considered organic fertilizers.

Manufactured organic fertilizers include compost, bloodmeal, bone meal and seaweed extracts. Other examples are natural enzyme digested proteins, fish meal, and feather meal. The decomposing crop residue from prior years is another source of fertility. Though not strictly considered "fertilizer", the distinction seems more a matter of words than reality.

Discussion of the use of the term 'Organic'

Some ambiguity in the usage of the term organic exists; this is because in the chemical discipline, organic denotes molecules containing one or more atoms of carbon. Because synthetic fertilizers, (such as urea) contain carbon, they are by this definition 'organic'. However, when describing organic fertilizer, 'organic' is used in the same sense as it is used in organic food; that is, "produced through natural processes".

Synthetic Organic molecules

Because synthetic fertilizers, such as urea and urea formaldehyde are able to synthesize chemically for mass production, and exist in nature, it would be difficult or impossible to chemically distinguish between pure urea of biological origin and pure urea produced synthetically.

Although it is widely thought^{[according to whom?]} that organic fertilizer is better than inorganic fertilizer, balanced responsible use either/or can be just as good for the soil, according to the PPI institute website.^[1].

Natural inorganic Organic chemicals

Some fertilizer materials commonly approved for organic agriculture are powdered limestone, mined rock phosphate and Chilean saltpeter, but are inorganic chemicals in terms of use by chemistry.

For further clarification, see organic.

Advantages and Disadvantages

Advantages

Although the density of nutrients in organic material is comparatively modest, they have many advantages. The majority of nitrogen supplying organic fertilizers contain insoluble nitrogen and act as a slow-release fertilizer.

According to a 32-year Swedish study into crop yields comparing organic and synthetic fertilization, yield increased in all treatments (organic and synthetic) in concordance with the overall trend of the Swedish agriculture, but the increase was highest in the organic treatments (65 % in the biodynamic in comparison with 50 % in the conventional)^[2]

Additionally, data analysis for soil physical properties, soil chemistry and soil biology collected after 19, 28 and 32 years of soil data showed that nearly all chemical (pH, P, K, Mg, C and N) and biological parameters (respiration, DHA, urease, earthworms) assessed were improved by organic fertilization whereas no such improvements were observed following the application of mineral fertilizer.

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.^[3]

Modern organic agriculture admits the truth of Liebig's theory of plant macronutrients, but stress that there are serious limitations to the current methods of implementing it via chemical fertilization^{[citation needed]}.

They 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, leading to eutrophication of bodies of water (which causes fish kills^[4])
Costs are lower for if fertilizer is locally available^{[citation needed]}

Disadvantages

Organic fertilizers can have disadvantages:

As a dilute source of nutrients when compared to inorganic fertilizers, transporting large amount of fertilizer will incur higher costs. Especially with slurry and manure ^[5]
The composition of organic fertilizers tends to be more complex and variable than a standardized inorganic product.
Improperly-processed organic fertilizers may contain pathogens from plant or animal matter that are harmful to humans or plants. However, proper composting should remove them.^[6]

Application

In non-organic farming a compromise between the use of artificial and organic fertilizers is common, often using inorganic fertilizers supplemented with the application of organics that are readily available such as the return of crop residues or the application of manure.

External links

Organic Fertilizer - explore.org

References

[1] ttp://www.ppi-ppic.org/ppiweb/ppibase.nsf/$webindex/article=2BEC38F385256C76005A2A9405D02997

[2] ttp://www.jdb.se/sbfi/publ/boston/boston7.html

[3] ttp://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TC7-4GDBRNX-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=10&md5=1e3f29ab6806e11cc63cd648dcb5a13d

[4] ttp://www.eoearth.org/article/Eutrophication

[5] ttp://www.extension.org/pages/Costs_of_Slurry_Manure_Application_and_Transport

[ciwmb-6] wmb.ca.gov - organics document

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