Soil Amendments and Compost

By Ron Alexander

Compost and other soil amendments have been studied for hundreds of years by horticulturists, agronomists and agricultural professionals. A variety of verified product benefits (potential labeling claims) have been identified through research over this same period of time. Below is a list of compost benefits that have been verified and should be available for suppliers or manufacturers to use on their product labels. The list is supported by the attached bibliography of scientific publications and text.

AAPFCO proposes the following as a minimum list of allowable product claims, which may be amended by suppliers or manufacturers with additional verifiable research data. It should also in no way restrict a specific supplier or manufacturer from making additional claims that are specific to a product, if they have research to support such claims.

Verified Compost Benefits

  1. Improves soil structure and porosity – creating a better plant root environment
  2. Increases moisture infiltration and permeability, and reduces bulk density of heavy soils – improving moisture infiltration rates and reducing erosion and runoff
  3. Improves the moisture holding capacity of light soils – reducing water loss and nutrient leaching, and improving moisture retentio
  4. Improves the cation exchange capacity (CEC) of soils
  5. Supplies organic matter
  6. Aids the proliferation of soil microbes
  7. Supplies beneficial microorganisms to soils and growing media
  8. Encourages vigorous root growth
  9. Allows plants to more effectively utilize nutrients, while reducing nutrient loss by leaching
  10. Enables soils to retain nutrients longer
  11. Contains humus – assisting in soil aggregation and making nutrients more available for plant uptake
  12. Buffers soil pH

References

It should be noted that several of the following references provide documentation for many of the benefits of compost, but each reference may not have been repeated in all of the appropriate categories. It is also important to recognize that this is just a partial listing, and that hundreds of additional references could be cited to verify compost product claims.

1. Improves soil structure and porosity – creating a better plant root environment

2. Increases moisture infiltration and permeability, and reduces bulk density of heavy soils – improving moisture infiltration rates and reducing erosion and runoff

3. Improves the moisture holding capacity of light soils – reducing water loss and nutrient leaching, and improving moisture retention

4. Improves the cation exchange capacity (CEC) of soils – improving their ability to retain nutrients for plant use

5. Supplies organic matter

6. Aids the proliferation of beneficial microbes

7. Supplies beneficial microorganisms to soils and growing media

8. Encourages vigorous root growth

9. Allows plants to more effectively utilize nutrients, while reducing nutrient loss by leaching

10. Enables soils to retain nutrients longer

11. Contains humus – assisting in soil aggregation and making nutrients more available for plant uptake

12. Buffers soil pH

13. Binds and degrades specific pollutants

In several instances, and in order to reduce the volume of data for AAPFCO to review, the attached back-up package of compost research/use data is in ‘article’ form (condensed from the actual research papers). These actual full-length research papers can be supplied if necessary, and upon request.

Full Bibliography




Ron Alexander

Author Ron Alexander has a bachelors in horticulture from Delaware Valley College.

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