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3. Prospects of Success and Possible Fields of Hydroseeding

Among the favored applied hydraulic seeding procedures, there are some, which show basic differences in what concerns the applied components. Occasionally, new or modified procedures are developed, too.

The most common and most successful hydraulic seeding methods confine themselves to the specific products characterizing them and normally feature technically mature technologies.

Thus, we only address certain issues, which again and again produce uncertainties with planning and issuing offices.

As there exist unlimited site variants, resulting from the combination of geological-pedological, geographical, micro- and macro-climatical, hydrological and biological factors, principally each application demands for a project-specific component recipe from different seed blends, fertilizers, soil conditioners, mulch fibres and soil binders. Especially raw soils and similar extreme areas require a wide range of various components to achieve successful and permanent vegetation. To simplify the complex variety of differing sites, areas with similar characteristics can be summarized to groups of site types. How to treat them would go beyond the scope of this article; for a well-founded, scientific consultation, however, we are at your disposal. Among this is the compiling of a differentiated list of questions allowing an optimized approach to site conditions.

Here, the below listed specifications must be met:

 

  • Easy, incomplex and unperilous processing/handling
  • Ecological harmlessness
  • Lasting effect with widely constant quality
  • Resistance to wind as well as to temperature and humidity fluctuations
  • Resistance to the influences of solar radiation till the vegetation has closed
  • Harmlessness concerning the germination of seeds and the development of the vegetation
  • Compatibility with other additives (fertilizers, soil conditioners, mulch, etc.)

If the applied soil binders meet the mentioned specifications, the below listed technical and biological functions of hydraulic seeding methods can be fulfilled easily:

    • Prevention of soil erosion caused by water and wind
    • Reduction of the threat of slips of slopes
    • Protection of the applied seeds and other components against drift and washing away
    • Protection of the applied seeds against extreme climatic influences
    • Absorption and storage of precipitation water and dew
    • Promotion and acceleration of germination and development procedures
    • Promotion of an intensive and deep reaching root system

    Regarding a quick reinforcement with methods of bioengineering, seedings with grass and herb blends are superior to those ones with seeds of trees and bushes. In the long run, however, groves with their obviously deeper reaching root system and their protecting foliage provide particularly effective slope reinforcements. To achieve a short-term erosion control and a quick vegetation cover, low portions of nurse grasses, herbage and leguminoses, which are no threat to the grove seedlings, are added; the intermixture of grass species or grassland species is not suited, as this meant an enormous competitive pressure for germinating and young groves, which would be suppressed almost completely. Topsoil and soils composed of fine grains (silt, loam) generally offer quite good growing conditions to grass and herb species; thus, groves will only have a very small chance to develop under such a strong competition. Grove seedings on topsoil, silty and loamy soils are not to be recommended.

    A sufficiently thick mulch layer is of great importance to achieve adequate germination results. In the technical literature, coats of straw mulch with up to 600 g/m² are recommended; according to experience, this amount is optimal for grove seedings, the minimum amount ought not to be less than 400 g/m².

    In most cases, establishing vegetation with standard seed blends can be carried out successfully - with the exception of special sites like e.g. inland and coastal dunes, salt meadows, rocky sites, artificial substrates, etc. If, however, the focus is directed on the creation of a vegetation area for a certain use, or on aspects concerning nature conservation, then more or less specified seed blends or procedures are necessary to achieve the respective development goals (see also hay-mulch and Heudrusch®-procedures).

    To ensure professional restoration and permanent vegetation, the applied seed blends have to be adjusted to the respective site. The efficiency of a seed blend not only depends on its site suitability, the ecological behavior of the contained species and the allocation to a certain phythocenosis; a weight percentage distribution, which is harmonically synchronized and considers the thousand-seed weights of the individual species also is of great importance.

    Generally, seed blends from grasses and herbage of accredited seed suppliers are applied with broad ecological amplitude. Fortunately, establishing vegetation with regional seeds, which excludes the problematic extrusion of the local flora by uniform breeded species, becomes increasingly important (see also hay-mulch and Heudrusch®-procedures).

    Assumed that appropriate application techniques and professionally composed recipes are applied, almost every site can be successfully treated by hydroseeding, if the soil contains no phytotoxic components and if there are no other factors harmful to plants. Even slopes of up to 100 m form no exception, if top and bottom of the slope can be accessed with vehicles. However, if the established vegetation is of permanent quality, depends on the right selection of seeds and additives. The succeeding maintenance processes also may play an important role (for example, successive fertilization in due time, mowing or irrigation of the respective area).
     

    3. Prospects of Success

    Concluding Remarks

    This dealing with the wide range of the subjects "Hydroseeding" and "Establishing Vegetation on Problematic Sites" offers only a limited insight in the complexity of recultivation measures. BENDER disposes of long-term experience, a highly professional specialized staff and up-to-date engineering techniques to successfully meet the most varying demands and find the best possible project-specific solution. Consult us. We look forward to advising you!

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