The OmniVerdi Sigma nursery system is designed for the OmniVerdi Riza and is cheap and easily build with local materials, mostly available in local construction shops.
There are currently 4 designs to hold the seedling bags straight-up: within PVC-tubes, hanging bags with gypsite covers, wrapped in sheets buried in a hole and between rooftiles. The roof-tile system is the most recommended, with the lowest depreciation cost per produced seedling and highest post-project residual value. The wrapping + burying has the lowest initial nursery investment cost and enables the use of seedling bags with many different diameters and lengths better adjusted to each species requirements.
The seedling density per square meter for the tile design is aprox 250, included 50cm width walking alleys between the seedlingblocks.