Zambia -- How vetiver grass prevents erosion! Want to Learn More about Vetiver Grass?
Christian Reformed World Relief Committee (CRWRC) -- ZAMBIAhttp://www.crwrc.org/index.html
The Government of Zambia introduced Vetiver grass to the Eastern Province of Zambia late in 1996, so to date we have had 4 growing seasons. The initial supply was managed by Agriculture Officers of the government but one facilitator of the Reformed Church in Zambia's Planning and Development Department (RCZPDD) received 250 splits to establish a nursery where water was available. The nursery grew well and since that time the program has been giving vetiver splits to farmers from the nursery every year. In this specific area farmers only receive small amounts of vetiver and are responsible for propagating and replanting their own vetiver. In other areas that RCZPDD works, facilitators now network with government officers to get farmers larger amounts of around 5000 splits of vetiver.
Because the program often introduces farmers to vetiver along side of several other soil stabilising and improving techniques, it is difficult to assess the actual amount of improved maize yield vetiver has had. Vetiver is introduced and supplied to farmers only when contour bands are properly measured and earthen contour ridges (of about 6'') constructed. Often this will encourage the farmer to change their plowing and planting lines to follow the contour. While weeding farmers often pile dirt along the row of the crop creating micro contour ridges. Farmers have been very happy with these techniques and have found little to no run-off and increased moisture retention. In the past farmers reported that after a rain fall surface moisture could be gone in 1 to 3 days. With contour bands, contour planting and ridging farmers have found that surface moisture will be present for 1 to 3 weeks. This has makes a big difference early in the growing season when the rains are irregular. Farmers have found that having vetiver on the contour bands stabilises them, reduces labour intensive annual maintenance, and prevents them from rupturing with much rain. (Few slopes are greater then 5 degrees.) We have found that if farmers plant vetiver on their contour bands they are more likely to continue establishing contour bands with vetiver.
Although many more farmers have implemented contour bands then have planted vetiver, we have found that if a farmer starts with vetiver he will be convinced of it, and will continue to plant it and will give splits to others as well. Farmers who experimented with vetiver in problem areas where erosion was a clear problem found that it takes about two years to become well established, but after that there will be little erosion and the former gullies will be filled in. One farmer had a wash out that was as deep as his leg. Now, four years latter you can't tell there was ever a problem. This farmer is convinced and has been giving splits to fellow farmers to help them with problem areas. Farmers generally take splits from the existing band while leaving half of it there if they have no nursery. The original line will not be weakened much. Farmers have found that drought resistance (Zambia experiences 7 1/2 to 8 consecutive months with no rain) is not a problem if new splits are planted two months before the ends of the rains. Once established lack of moisture hasn't been a problem at all.
Farmers have found that vetiver does need a bit of maintenance. Some farmers like to cut it back to 50cm, which can be done quite easily with a very sharp sickle at the beginning of the rainy season. In some cases this is done to take out the dead shoots and to stimulate new growth, in other cases it is done so the farmer can plant closer to the vetiver. Some farmers also see it as necessary to clean around the base of the plants at the end of the growing season. Grass fires are a big problem in Zambia so cleaning dead growth from the base of the plants could prevent the grass fires from burning established stands. However, farmers have reported that if a row of vetiver is burnt it will grow back again. No problems were found with vetiver spreading or causing other problems. Animals were reported to eat a bit of it, which appears not to harm either plant or animal. In the event that a plant does die out farmers have waited until the next rainy season to replant.
While the idea of planting vetiver on contour bands in Zambia is relatively new contour bands themselves are not. With vetiver becoming more available and with farmers understanding its potential we feel that contour bands will become more permanent structure. In the past, with only earth structures contour bands not only broke with excess water, but if they where not maintained for a year or two they virtually disappeared. With vetiver established on ridges, contour ridges will maintain themselves much better and become very permanent structures, encouraging other soil conservation and water retention techniques.