The Essentials of Rainfed Farming in Subsistence Agriculture

Wednesday, May 22, 2013

This article is contributed by guest blogger:
John Greenfield - Director, The Vetiver Network International

As everyone who has ever had a basic garden knows, growing plants requires soil moisture - not just rain.  Individual plants cannot harvest enough water on their own from the rainfall runoff that passes them by. This essential moisture has to be held in the soil where it is available to the root system of the plant and not lost to the drainage network.  This is the basis of “rainfed” agriculture.  An extremely simple fact, but one that seems to be constantly overlooked as scientists try to develop the perfect “drought resistant plant”. Rarely will you see mentioned "controlling runoff" mentioned in research papers on rainfed farming.

In India, for example, I have seen millet crops germinate as the result of 9 mm of rainfall at the beginning of the wet season – then there was no further rain for six weeks.  Those little plants withered and died, and the farmers lost that crop. What is worse, some farmers not only lost their crop, but they also lost their seed and couldn’t ‘replant’. The district was declared a drought area, but this announcement was no help to the farmers, they were now desperate.

Fortunately for us, we had been trying to get these farmers interested in the “Vetiver System” (VS) by telling them that vetiver hedges had the ability of slowing down runoff, spreading it out and giving it as chance to soak into the soil while filtering the silt and nutrients out of that runoff. The increase in yields they would see from practicing VS would convince them that this essential technology of moisture conservation - initially labor intensive but not expensive - was essential to their future. 

We had held a meeting of these farmers to explain VS, and got some farmers to volunteer their land to try the system out. Those farmers received the same rainfall as their neighbors but, in their case, their vetiver hedges retained the 9 mm rainfall, spread it out, and let it soak in to the soil.  This gave their plants sufficient moisture to carry them through the six weeks without rain.  After this dry period the rainfall was more than adequate and the farmers with VS produced some of the best crops they have ever had.

All that is required to achieve that essential vetiver barrier is the planting material and a farmer’s bare hands (as can be seen in the picture of an Ethiopian farmer planting just such a hedge). No bulldozers, engineering, dumpy levels, administrative staff, costly vehicles or support infrastructure.  No foreign experts, no meetings to plan contour-layouts.  Just the farmer and some planting material can achieve a permanent system of soil and moisture conservation leading to sustainable crop production and increased yields without losing his soils and nutrients through erosion.

Vetiver hedges do not have to be planted on the contour and are actually more useful planted across the slope; this makes it easier for the farmer to follow them with his plow. In spite of their massive root system (see picture) vetiver hedges do not compete with crop plants in anyway. In fact, they may enhance growth near the hedges due to the extra moisture and nutrients held there, and their symbiotic mycorrhiza the benefits of which crop plants can also share.

This vetiver system is different from constructed soil conservation systems that are actually rainfed negative, especially in the tropics, by diverting the rainfall runoff in to waterways. Contour banks, diversion banks, and absorption banks and are a total misconception when it comes to rainfed farming.

Vetiver hedges can hold back 300 mm of runoff, but the rainfall that filters through the hedges naturally waters the land immediately below the hedge – this is the ‘flow through system of soil and moisture conservation".  Vetiver hedges, because of their massive root system, cannot be breached – whereas conservation banks, once full to overflowing, are easily breached and can cause massive gullying when this happens.

Not even the best bred, drought tolerant crop plants (there is no such thing as drought resistant plants) with weed and pest control and ideal fertilizer applications with all their inherent costs, will produce a sustainable crop result without the essential soil moisture.

In many parts of India, the only fertilizer the subsistence farmer has is made from his farmyard manure and straw. With commendable effort this fertilizer is gathered up as compost and carried to the field in "head loads" and applied by hand. Unfortunately, if the first rains are relatively heavy, the fertilizer is floated away and lost to the drainage network. We found that with the benefit of vetiver hedge barriers that spread out the runoff and slow it down, the fertilizer is not lost.

In conclusion, the essential ingredient of rainfed farming is the control of runoff.

John Greenfield introduced the Vetiver System concept to India in 1980s.  He is the "Father of Vetiver" and authored the "Green Book" - Vetiver Grass-A Hedge Against Erosion. He is a director of The Vetiver Network International and lives in the Bay of Islands, New Zealand.

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