TECHNICAL INFORMATION

Georgia Pine Straw has been a leader in superior pine straw production for years, but did you know that pine straw itself has proven to be one of the most effective mulches from a scientific standpoint?  If you don’t believe us, just take a look for yourself at all the benefits of pine straw below!

 

Many grounds-care professionals prefer particular mulches, but what’s best for a site actually depends on the needs of the situation.  Although mulch producers often make claims about the durability, composition or colour, little research exists to confirm such claims.  A team of Florida researchers recently evaluated the characteristics of six organic mulches to define their qualities and usefulness for certain situations. The researchers obtained commercially available local mulches from:

 

Cypress
Eucalyptus
Pine bark
Pine needles (Pine Straw)
Melaleuca
Utility trimmings.

 

The researchers tested them for chemical, allelopathic and decomposition properties. The concluded the following: 

 

Nutrients
The most nutrient-laden mulches were the utility trimmings and pine straw. Both of these mulches contained less than 1% nitrogen.  The nitrogen content in the utility mulch was due to the presence of green leaves in the material.
The presence of nutrients in the pine straw supports the research done by several Universities on the Fertilizing of Pine Plantations.  Research has found that repeated annual rakings deplete nutrient reserves at the pinetree plantations.  It is estimated that the raking and removal of the pine needles, removes 20 lbs of Nitrogen and 2 lbs of Phosphorus per acre. It is recommended that Plantations apply 175 to 200 lbs Nitrogen, 50 lbs Phosphorus and 50 lbs Potassium per acre on areas raked annually.

 

Decomposition
The most decomposition resistant materials were pine straw, bark, cypress and melaleuca. These materials contained higher levels of lignin than the utility trimmings and eucalyptus.  Lower decomposition rates result in longer intervals before mulches need to be reapplied.

 

Allelopathy (Weed Control)
All of the mulches tested were initially allelopathic due to the presence of certain aromatic compounds.  The researchers measured the allelopathy in terms of germination suppression.  The most allelopathic mulches were the pine straw and the utility mulch which both suppreseed seed germination after 1 year. The majority of the mulches lost their allelopathic qualities within a few months.

 

Acidification
All mulches lowered the pH of the underlying soil.  In the evaluation, the initial soil pH was 5.0.  After 1 year, eucalyptus lowered pH to 4.8, utility trimmings and melaleuca lowered it to 4.7, cypress and pine bark lowered to 4.6, while the pine straw dropped the pH to 4.4.   The researchers considered soil acidification a drawback, but this trait can be beneficial depending on initial soil pH and whether the existing plants prefer acid soils.

 

Color
All mulches lose their initial color.  The rate of color loss is dependent upon the conditions. The graying of the mulch is mostly on the surface where the sun has impacted. If the mulch is raked some of their initial color will reappear.  If color is a concern, best solution is to replenish the mulch with a thin layer of new mulch.

 

Summary
There is no perfect mulch for all situations.  An understanding of the differences between materials should help the grounds managers choose the most ideal mulch for a given site.