Microbial Root Dip for Vetiver

A simple dip made on the farm that helps new vetiver slips take root, grow and survive. Why, the recipe, how to apply it, and what to expect.

1. Why use the dip?

Vetiver works closely with two kinds of soil life. Mycorrhizal fungi (AMF) grow out from the roots like a second root system, bringing in phosphorus, other nutrients and water. Helpful root bacteria (PGPR) stimulate root growth and help keep root diseases down. Giving new slips both partners at planting helps them take root faster, survive dry spells and start tillering sooner. Everything comes from the farm: compost, soil from beside mature vetiver and, if available, termite-hill soil. Bought fertilizer or nitrogen-fixing products are not needed; vetiver grows in poor soil and does not need them.

2. Recipe

Separately, collect AMF soil: the top 30 cm of soil, with fine roots, from 10–20 cm beside a mature vetiver clump. If there is no vetiver, use soil from Napier, Rhodes, Guinea or Setaria grass. Do not brew the AMF soil, because the fungi live only on living roots. Never use kikuyu roots (invasive), and do not use fresh manure or a fermented brew such as RONGO as a root dip.

3. How to apply it

1. Soak the slip roots in the strained dip for 30–120 minutes, in the shade.
2. Add a pinch of AMF soil to the dip.
3. Put 1–2 tablespoons of AMF soil in each planting hole, touching the roots, and plant at once.
4. Make a fresh batch for each 50 m or so of hedge.

4. Expected benefits

Research shows that mycorrhizal fungi increase vetiver growth and phosphorus uptake, raise its oil yield and can reduce root nematodes. In the field, expect better survival, faster tillering and more drought tolerance. Crops such as ginger, turmeric, banana, citrus, coffee and vegetables respond strongly to these fungi. Whether vetiver passes the benefit on to the crops next to it is likely but not yet proven, and that is one of the things GVF is testing. The amounts and times above are working rules, not exact figures. Test it yourself: plant one stretch of hedge with the dip and one without, in the same soil, and record survival and tillers over two or three seasons.