Soil Moisture Conservation and the Vetiver System

Although there are many other applications, Vetiver's most important use is for soil and water conservation, and the need to use Vetiver for this purpose is growing every day as the negative impacts of climate change accelerate.  This is especially the case in the poorer areas of the tropics and semitropics, including semi arid areas. Sadly the technology is not being used as much as it should for this purpose.

India is one such example - as the center of origin of Vetiver grass (Chrysopogon zizanioides) and with a traditional on farm use going back hundreds of years, it still is relatively unknown.

We would urge individuals, communities, and other development agencies to use vetiver hedges for soil and moisture conservation in their programs. We are familiar with the “microwatershed development” approaches being utilized in India and other countries that have (in our opinion) a number of problems that detract from long term success … problems that vetiver hedges are very well-suited to help resolve.  


Briefly, microcatchment approaches (that exclude vetiver) being used:

1. Concentrates work along the natural drainage ways to capture all of the rainfall runoff possible for productive use.  This focus: (i) means that farmers whose land is some distance from drainage lines receive no direct benefits (in fact have negative benefits); and (ii) distracts from what should be the key approach of infiltrating the rainfall into the soil that it falls upon and, if surface runoff occurs, to halt it, infiltrate it, and store it in the soil for use by crops and to recharge groundwater.

2. The use of soil bunds to control erosion and halt runoff results in less soil moisture recharge.  It is true that near the bunds there is additional soil moisture recharge, but bunds halt the runoff and concentrate it, and the significant “excess” needs to be channeled safely off the field.  With vetiver hedges the is no “excess”.  The hedges halt the runoff and, being semipermeable, spread it out and allow it to move through slowly and infiltrate both above and below the hedge.  Done correctly, most of the rainfall that falls on the famers’ fields will be infiltrated and stored for use in their soils (and will recharge groundwater).

3.  In the arid and semi-arid areas of India, evaporation from open water surfaces (farm ponds, nalla bunds, village tanks, etc.) can be up to 3,500 mm per year (http://www.nih.ernet.in/rbis/india_information/evaporation.htm).  When water is stored in this way, very significant amounts of it is lost to evaporation.  If the goal of water storage is for other than domestic and livestock use, it is better to enhance soil moisture and groundwater storage where it will not result in vast quantities of water being lost through direct evaporation into the open air.

4.  Unknown downstream impacts.  Over the centuries, villages in India had come to rely upon a status quo hydrologic system -  that is, village tanks and nalla bunds historically were recharged as a result of the land and water usage patterns that defined their catchment’s hydrology.  The rise in the last decades of the microwatershed approach of capturing 100% (or almost 100%) of the water upstream in many cases is alleviating one villages water shortages at the expense of another villages historic water supply.  Water has become so scarce in India’s arid and semi-arid zones (and even much more so when you realize how much of the existing water supply is contaminated and not available for domestic, livestock or agricultural use as a result) that it has to be understood as a zero sum proposition. Agencies/associations of what ever kind that are trying to help poor villagers need to think beyond the microwatershed to the larger watershed and join together with others to find approaches that do not rob one farmer to benefit another!

The beauty of Vetiver grass hedgerows is that when applied to a micro catchment they will benefit all farmers who use them (most importantly soil moisture, and increased soil fertility, crop yields, reduced soil loss, reduced pest damage, improved drought proofing, increased forage and other benefits). Catchment groundwater increases results in improved well water levels, and spring and stream flows.  None of these actions/results will be detrimental to downstream users - in fact downstream users of all kinds will all benefit from improved hydrology and reduced sediment flows in streams and rivers.  The overall investment and maintenance costs will be lower, and the dependence on costly and often ineffective government services will be reduced.

The above statements are all backed by research data and observations from many different countries.  Additionally there are plenty of examples from farmers and other users that show how using vetiver grass hedgerows have completely changed the lives of farmers and have protected their lands to the extent that have enabled other beneficial farm practices.  Here are links to few such examples:

The Chikukwa Permaculture Project (Zimbabwe) – The Full Story.
Vetiver Grass and its system for community development in Ethiopia

Vetiver System Contribution for Wetland Rehabilitation in Ethiopia

Vetiver's poverty alleviation achievements propel dissemination in Indonesia

Vetiver Grass for Soil and Water Conservation, Land Rehabilitation, and Embankment Stabilization (collection of news letters and research results)

Poverty Alleviation Using the Vetiver System In Tropical Developing Countries.
Green Structure for Soil and Water Conservation on Cultivated Steep Land

Those who use Vetiver Grass hedgerows attest very positively to their benefits; problems remain in disseminating the technology to potential users, and the failure of policy makers and technicians to recognise the real and costly issues relating to the traditional engineering approach that has on the whole failed to serve the small and poor farmers in the developing world.

Listen to Caleb Omolo who farms 5 acres in Kenya.  He has got it right!!

https://www.youtube.com/watchv=TLFRS4-WZyY

Dick Grimshaw and Jim Smyle