RST Environmental Solutions Ltd

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Hydroseeding was developed in the USA in the 1950s as a means of getting vegetation to establish on difficult sites. The systems have come a long way since that time and RST Environmental Solutions have developed systems that are suited to New Zealand conditions. The hydroseeding units are truck based in two, four and six wheel drive configurations.

Track based machines are also available for difficult or wet areas unsuitable for wheel machines. The hydroseeders have hose reels that can reach up to 100 metres from the machines and mounted water canons can shoot up to 50 metres vertically. These machines are designed to be extremely versatile and are able to supply a number of different systems.

The hydraulic seeder unit applies seed using water to areas that are difficult to access. It can apply a wood fibre product, including a tackifier, that allows the seed to be covered in mulch that sticks to steep areas, whilst the mulch cover allows extra moisture retention. Several tackifiers that can be used in such different situations as holding the soil in place, through to being rain-fast.

Because the system surface seeds soil temperatures don't unduly effect seeding emergence, seeding can occur throughout most of the year. Dry periods in the summer should be avoided unless irrigation is available. The system is designed to stick the seed to the slope and relies on the seed to germinate and grow to create root mass on the slope, which in turn provides stability. It is also what is normally used on flat areas to establish lawn or to bind road shoulders.

There are a number of variations on this base system which include the addition of soil flocculants, rain fast tackifiers, and soil bacteria and fungi. These extra products are added dependent on the site conditions experienced. Generally, it takes between three and six weeks for the seedlings to fully establish and provide good stable cover.

This is a proprietary system we import from Canada, which is applied to a slope using a hydroseeder. The result is a blanket of interlocking wood fibres which make firm contact with the soil, and a supporting sub system, via a bonding agent that locks the soil particles together to the fibre blanket.

The wood fibre dries to create a high-strength porous and erosion-resistant mat which absorbs the impact of rainfall while allowing the water to filter slowly through the soil. In heavy rain, water will sheet off to prevent rilling. In many situations an EcoAegis BFM can replace a roll out geo-textile and has the ideal for fretting papa or clay banks and stabilising sand.

Hydrobush is a native hydroseeding system which can prove very cost effective on sites that don't require an immediate landscaped look. Seed from native species, generally localised to the site, is processed and hydroseeded. It generally takes between 6 - 18 months for the seedlings to establish on site. Hydrobush is also ideally suited to work in conjunction with our moss and fern systems.

Hydrobush was released as a commercial operation in 2000. It follows a research and development programme we ran at Massey University and validation work that has been undertaken by Landcare Research.

Hydroseeding natives has historically been quite unsuccessful. The seed is generally supplied through a seed company or nursery without any background as to its source and quality and then directly applied. Our new system identifies the appropriate species and the correct time to collect seed. We then analyse the quality of the seed lines and assess the techniques required to treat the seed prior to sowing.

Hydromoss is a system that hydroseeds moss, lichens, and vascular plants onto areas to establish a base vegetation system. It is often used in conjunction with the Hydrobush system. And is particularly effective on rock faces, mudstones and any areas that have a low pH or fertility level.

This system was first developed by HortResearch and Landcare in conjunction with Solid Energy and RST Environmental Solutions for use in coal mines, but the technology is now available for a wider range of applications.

Mosses and lichens are generally eco-sourced from the area and then processed into a form where they can be reapplied. Other plant material, such as vascular plants, are also identified and can be added to the mix at the time of application.

The mosses generally establish quite rapidly and can give a good visual cover within 6 - 8 months. The mosses don't necessarily require damp wet sites and can establish on north-facing full sun sites. Hydromoss is ideal to combine in with either our Hydrobush or Hydrofern systems. It is ideally suited to mine and quarry sites and areas that are difficult to plant.

By establishing the low-growing legume-based shoulder, VergeBinder, a number of maintenance issues can be addressed. Currently, the road shoulders are left to re-establish themselves, following reseals or road improvements. This will happen over a three to four-year time frame and therefore allows the fine material on the shoulder to be disturbed by passing traffic. This in turn can start problems with low shoulder and edge break.

Roadside weeds such as fescues and ryegrasses, also establish and grow to significant heights. These cause visual obstruction as well as limiting drainage on the shoulder and increasing mowing costs. Damage from farm vehicle tracking on the shoulder can also be reduced using this system.

Species currently growing on the road verge have generally come from the surrounding farmland areas, and are designed to produce high dry matter production for farmers. The effect of which is to create high volumes of mulch on the road verge following repeated mowing. Ryegrass, Cocksfoot, or Fescue can produce up to 3000 kilograms of dry matter per kilometre of road verge per year. (Figures are extrapolated from agricultural statistics).

This mulch rots down to form a humus layer but also raises the verge and helps to degrade and block the water table. By establish in a low growing legume based verge a number of the problems highlighted previously can be significantly reduced or eliminated.

RST Environmental Solutions has established a mix of small leaf legumes and grasses that establish well on the road verge, do not tend to invade the seal and grow to a maximum height of 100mm. These types of species only produce about 200 kilograms of dry matter per kilometre of road.

With the level of dry matter production being significantly reduced, issues such as high shoulders, and blocked and over grown water tables can be reduced. This means the mowing frequency can be reduced to approximately one-two mows per year. The weeds can be controlled in the first year by using a low rate of Glyphosate which will need to be repeated about every second year.

Hydrofern is a system that hydroseeds fern spare, gametophytes and rhizome material onto a site. It is ideally suited for papa banks and areas where ferns will typically grow. HydrofernTM has been developed to run in conjunction with our HydroBush and HydroMoss systems.

Hydrofern technology has been developed following a three year research programme that concluded at the end of 2005. It will be commercially trialed over the next 18 months before being released on a fully commercial basis.

Native Hydroseeding
RST Environmental Solutions, over the past 4 years have developed a native Hydroseeding system. This system uses species such as Coprosma, Hebe and Pittosporum to establish native vegetation.

It is ideal for establishing on heavily disturbed sites that don't require immediate cover as the natives are initially slow to develop. Typical plant densities of 3-4 plants per square metre are generally achieved. Other native species can be used and are generally eco-sourced.


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