Organic vs. Chemical

• Examples of naturally occurring organic fertilizers include manure, slurry, worm castings, urine, peat, seaweed and guano. Green manure crops are also grown to add nutrients to the soil.  Some examples of a winter cover of green manure crops are: winter rye, field peas, ryegrass, crimson clover, and hairy vetch.  These have the benefit of protecting your soil from wind and rain erosion and adding valuable organic matter and humus to the soil for the spring.   Naturally occurring minerals such as mine rock phosphate, sulfate of potash and limestone are also considered Organic Fertilizers.

• Examples of manufactured organic fertilizers include compost, dried blood, bone meal and seaweed extracts. Other examples are natural enzyme digested proteins, fish meal, and feather meal. read more

The decomposing crop residue from prior years is another source of fertility. Though not strictly considered "fertilizer", the distinction seems more a matter of semantics.  Nutrients, organic matter and humus from decomposition of crop residue and green manure crops all play a part in adding fertility back to your soil and feeding the microorganisms that are all a part of a healthy soil.

Some ambiguity in the usage of the term 'organic' exists because some of synthetic fertilizers, such as urea and urea formaldehyde, are fully organic in the sense of organic chemistry. In fact, it would be difficult to chemically distinguish between urea of biological origin and that produced synthetically. On the other hand, some fertilizer materials commonly approved for organic agriculture, such as powdered limestone, mined "rock phosphate" and Chilean saltpeter, are inorganic in the use of the term by chemistry.

Although the amount of nutrients in organic material is low when compared to many synthetic fertilizers, they have some advantages. For one thing organic growers typically produce some or all of their fertilizer on-site, thus lowering operating costs considerably. How effective they are at promoting plant growth, chemical soil test results aside, is encouraging, especially when you consider the impact on the overall health of the environment. Since the majority of nitrogen supplying organic fertilizers contain insoluble nitrogen and are slow release fertilizers their effectiveness can be greater than conventional nitrogen fertilizers with less leaching of excess nitrogen.

Modern theories of organic agriculture 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

Organics also have the advantage of avoiding certain long-term problems associated with the regular heavy use of artificial fertilizers:

• the possibility of "burning" plants with the concentrated chemicals (i.e. an over supply of some nutrients)

• the progressive decrease of real or perceived "soil health", apparent in loss of structure, reduced ability to absorb precipitation, lightening of soil color, etc.

• the necessity of reapplying artificial fertilizers regularly (and perhaps in increasing quantities) to maintain fertility

• the cost (substantial and rising in recent years) and resulting lack of independence

Organic fertilizers also have their disadvantages:

• As acknowledged above, they are typically a dilute source of nutrients compared to inorganic fertilizers, and where significant amounts of nutrients are required for profitable yields, very large amounts of organic fertilizers must be applied. This results in prohibitive transportation and application costs, especially where the agriculture is practiced a long distance from the source of the organic fertilizer. One of best organic fertilizer with many nutrients is Vermi compost fertilizer.

• The composition of organic fertilizers tends to be highly variable, so that accurate application of nutrients to match plant production is difficult. Hence, large-scale agriculture tends to rely on inorganic fertilizers while organic fertilizers are cost-effective on small-scale horticultural or domestic gardens.

In practice a compromise between the use of artificial and organic fertilizers is common, typically by 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.

It is important to differentiate between what we mean by organic fertilizers and fertilizers approved for use in organic farming and organic gardening by organizations and authorities who provide organic certification services. Some approved fertilizers may be inorganic, naturally occurring chemical compounds, e.g. minerals..

It is also important to realize that while the effort required to maintain a healthy soil where intense growing is continual can be a challenge, the effort will pay off in the long run by producing healthier crops and leaving behind a healthier environment.