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  4. Hydroseeding vs Hydromulching
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Hydroseeding and hydromulching are often used tandem, however, there are a few key characteristics that differentiate the two processes.

Ultimately, almost all construction sites require grassing, so knowing the options is imperative to finding the best option for the area. Depending on what the desired outcome is, as well as how reliable the result needs to be, is what decides whether hydroseeding or hydromulching will be the selection.

Hydroseeding was originally a way of distributing seeds with water, which then helped to develop an improved system of hydromulching to ensure seeds stay in place and have adequate moisture levels.

Firstly, hydroseeding contains little to no mulch so will provide significant differences in the outcome of the area. This is usually done due to restraints in the budget but is not recommended as can provide undesirable and unguaranteed results.

In contrast, hydromulching has the benefit of providing the mulch into the mixture that is sprayed with the seeds so provides a greater chance of germination and adequate growth.

Hydromulching is significantly more costly than hydroseeding, however is less costly than solid sodding. Depending on your budget and time constraints will determine the most effective option for you.

Straw mulch and Hydraulic mulch were both designed for erosion protection. Hydraulic mulch provides superior and cost-effective erosion protection for Bonded Fibre Matrix requirements. Straw Bonded Fibre Matrix proclaims to combine exceptional erosion protection and vegetative establishment. 

DuraVegTM Fibre Matrix is a Thermally Refined® wood fibre hydraulic mulch and has many reasons why it performs above other varieties of mulch. Wood fibres have significantly larger surface area in comparison to the likes of sugar cane, straw, and paper, and therefore creates greater yield, interlock, loft and coverage. 

Straw mulch is pre-mixed and contains wheat straw fibres, “natural fibres”, and proprietary cross linked tackifiers. There are limited tested performance or index properties to authenticate the claims of ‘exceptional erosion protection’.

Hydraulic mulch is hydraulically applied, 100% biodegradable, and has a functional longevity of approximately 12 months. DuraVeg Fibre Matrix is made up of Thermally Refined® virgin wood fibres, crimped, interlocking natural fibres, and performance enhancing additives.

As hydraulic mulch, Engineered Fibre Matrixes (EFM) is applied to the land, it forms a bond with the soil surface to create a continuous, porous, absorbent and erosion resistant medium that promotes rapid germination and accelerated plant growth. 

There have been tests carried out to determine the erosion control effectiveness of hydraulic mulch EFM and it has been rated as more than 95% effective at reducing soil loss, while straw mulch BFM does not report percent effectiveness values. 

Establishments are also made on the vegetation of the land area when using these two types of products. Hydraulic mulch establishes 600% more vegetation than bare soil, whereas Straw BFM establishes only 186% more vegetation than bare soil.

That shows Hydraulic EFM increases vegetation more than three times as much as Straw mulch BFM. Functional longevity is critical for the product to continuously encourage growth and germination within the soil to ensure longevity of the grass.

Hydraulic mulch EFM has a documented functional longevity of up to 12 months, whereas Straw mulch BFM does not report a value for this variable, however, previous ASTM D5338 testing suggests that straw based HECPs (hydraulically-applied erosion control products) similar to Straw BFM will only persist for up to 3 months. 

Lastly, environmental attributes are imperative in the present day due the effects additives can have on the environment.

Hydraulic mulch has been proven to be 100% biodegradable, in contrast, Straw mulch has not shown proof of environmental safety. 

Cellulose mulch (also called paper mulch) forms a two-dimensional matrix when applied to the soil and does not effectively retain moisture or prevent erosion. It then forms a 'paper mache', causing difficulties for the seedlings to grow through.

Use of cellulose mulch should be limited to the tacking blown straw or the seedling of flat to gently sloped areas where irrigation is in place. 

Wood fibre mulch is derived from wood chips that are ground until converted to fine intertwined fibres. Profile then uses a thermal refining process which maximises mulch performance.

Thermally Refined® wood fibres are very fine and have more surface area compared with atmospherically refined fibres which are shorter and coarser. Wood fibres also hold more moisture than paper, which makes wood fibre superior in mulch mixtures.

It also provides enhanced protection against weather elements and is consequently superior to cellulose mulch. 

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Advanced fibre matrices are wood based but engineered to be crimped biodegradable interlocking fibres with adhesive properties to increase matrix and bond strength.

Flexterra High Performance Flexible Growth Medium (HP-FGM) is an example of an advanced fibre matrix that is proven to exceed 99% effectiveness and longevity of up to 18 months or longer.

This is compared to wood fibre mulch which only has up to 75% effectiveness. Therefore, if greater than 75% erosion prevention effectiveness is desired, Advanced Fibre Matrices should be specified. 

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Erosion Control Blankets and Hydraulically applied erosion control products are two of the most commonly procured erosion control products in the market.

Some erosion control blankets can contain a ‘degradable’ plastic mesh that is placed over an eroded area to help control the rate of erosion.

These plastic nets can add additional harms to the environment due to the micro-plastics being broken down and getting into waterways, contributing to the accumulation of microplastics in the environment.

Wildlife in the area is also at risk as the mesh can cause entanglement, hence why many areas have imposed strict limitations or even bans on these products. Currently, HECPs pose no known risk to the environment or surrounding wildlife. 

Site access is also a key factor when assessing the options of an Erosion Control Blanket or HECPs. Areas requiring erosion control products can often be situated in difficult to reach areas, so it is crucial to assess the site access, especially regarding employee safety.

In extreme cases to install an ECB can cause many issues due to large slopes, meaning workers would have to wear safety harnesses. HECPs are able to be applied aerially to steep slopes or areas with limited access, making the process significantly safer than installation of ECBs. 

Soil properties are additionally a vital factor when deciding on erosion control products. With rocky or difficult to prepare areas ECBs may be impractical as they require a flat surface in order to be effective. As they require pins and staples to be held down it may be problematic to execute.

HECPs can be applied to these surfaces without any additional labour required to meet the soil properties. Other amendments may also be needed by the soil which can be applied in the same application as the HECPs. 

Hydraulic seeding and mulching techniques have become increasingly advanced and can provide more than 99% erosion control effectiveness. Functional longevity is a major aspect of whether the hyrdomulch is effective.

When using wood fibre mulch, it can have up to 75% erosion control effectiveness, and when using Advanced Fibre Matrices within the hydromulch it provides upwards of 99% erosion control effectiveness.

The Double Net Excelsior ECB exceeds 97% effectiveness, and a 0.03 C-Factor evaluation whereas the Flexterra HP-FGM exceeds 99% effectiveness with a 0.01 C-Factor evaluation. The C-Factor is the ratio of soil loss on the unprotected slope versus the soil loss on the treated slope. 

 

Learn more about Hydromulching:

Hydromulching Frequently Asked Questions

Highlighting the capabilities and frequently asked questions (FAQs) around Hydromulching and how DuraVeg can products and services and can assist with your project's needs.

 

What Are Tackifiers?

Tackifiers are chemical compounds, primarily a blend of polymers and polysaccharides, which form a binding attribute to keep the seeds and fibre in place during germination.

Tackifiers have valuable attributes as they can help defend from weather elements by ensuring stability and adhesion to the soil.

This characteristic is paramount for areas where soil is rough graded or has extreme weather conditions that mean ensuring bond of seeds to the soil is imperative.

The use of tackifiers is optimum for these conditions and has proven to make a significant difference in areas lacking flat or favourable properties.