The soils of Madagascar are generally nutrient poor and forests display rapid nutrient cycling. Nutrients in these forests are not readily available as they are tied up in biomass. The majority of native vegetation is dependent on fungal root associations for nutrient uptake. These symbiotic associations between fungi and the roots of plants are termed vesicular-arbuscular mycorrhiza (VAM) or ectomycorrhizal (ECM). It is termed ‘symbiotic’ as the fungus obtains carbohydrates (sugars) from the plant and in exchange provides the plant with vital nutrients for growth. It is not possible for the plant to obtain many of these minerals by itself without the fungus. The fungus thus helps plant growth and health by increasing the plants nutrient absorption capability. Examples of these nutrients are phosphate, nitrogen and other minerals. Seedlings produced at community nurseries for reforestation projects often lack these important fungi in potting mix. The absence of mycorrhiza impacts on the health and growth of seedlings resulting in higher mortality rates – in the nursery and once planted in the field.

Ny Tanintsika has begun establishing trials to produce the VAM for seedling production at community nurseries. The process is relatively simple but will hopefully prove essential to the production of healthy native seedlings.

The process used for producing VAM at the community nurseries is detailed below.

1. root material is collected from the undisturbed forest that contains mycorrhiza of the plant families grown at the nursery
2. a trench is dug that is 50cm deep but can be varying in width and length (depending on the amount of VAM required)
3. the trench is lined with a breathable plastic sheet to keep in the moisture & fungus
4. the collected root material is added to the trench
5. a small amount of topsoil and compost is placed on top of the forest soil
6. a mix of rice and bean seeds are sown and the pit is watered
7. the rice and bean mix is grown for 3 months to help culture the fungi as the roots provide a new medium for mycorrhizal growth
8. reeds or straw is placed on top to keep the mixture from drying out
9. after 3 months the rice and bean plants are cut and mixed into the mycorrhizal culture
10. water drainage is installed to stop rain water running into the mixture (especially during cyclonic events)
11. after a further 10 days the culture is ready to add into the potting mix in poly bags
12. 1 tablespoon of the culture is added to the poly bags for seedlings