Paul N. V. Truonga and Jal S. Gawanderb
aResource Management Institute, Queensland Department of Primary Industries, Meiers Road, Indooroopilly, Qld, 4068, Australia.
bCane Research Centre, Fiji Sugar Corporation, P.O. Box 5660, Lautoka, Fiji.
The concept of using Vetiver grass for soil and water conservation purposes instead of conventional structures was first developed for the sugar industry in Fiji more than 50 years ago. The Vetiver system is now widely used as a standard practice for soil and water conservation, particularly on small farms. The Vetiver system is very effective in erosion control and it is well accepted that when properly implemented the system can improve sugar cane yield up to 55%. Over a 40 year period terraces formed from eroded soil upslope are up to 1.5 m high. However farmers are now reluctant to implement the Vetiver system and in some cases are removing the well established system, resulting in massive erosion and production loss. The reasons for low adoption, and in some cases rejection, are complex but include socio-economic, land use policy and agronomic practices. Problems associated with these issues are identified and possible solutions are proposed.
Vetiver grass was first used for soil and water conservation purpose in the Fiji sugar industry early in the 1950's. The success of the Vetiver system is highly visible in the form of 1 to 1.5m high terraces built up from trapped sediment on numerous canefields on the west coast of Fiji. However, despite this highly effective means of soil and productivity conservation, farmers are now reluctant to implement the Vetiver system.
The Fijian experience provides an extremely rare opportunity to observe with reality, not by modeling, but with actual outcomes, what is the impact of the Vetiver system after 50 years of application. Lessons to be learnt and pitfalls avoided, so that this new technology continues to protect our environment and conserve our limited' resources for future generations.
Vetiver grass was first introduced to Fiji from India probably late in the 1800's to provide thatching material for houses and it is still being used for roofing and walls. Although it was commonly used to stabilize embankments, terraces and to delineate farm boundaries, its application as a soil conservation measure as we know today was developed early in the 1950's. On Viti Levu, which is the main island, the Fijian sugar industry concentrated along the west coast where suitable low slope land is very limited. As the sugar industry expanded, the main sugar production company, Colonial Sugar Refinery (CSR) was faced with a very severe soil erosion problem on sloping lands, particularly on the north western area around Rakiraki, where the land is very steep and rainfall is often of very high intensity.
A team of research agronomists and soil conservationists including John Greenfield at the CSR Agricultural Experimental Station first tried the accepted methods - engineered contour banks, diversion banks, leading to grassed waterways, but under tropical rainfall conditions these structures did not last a season. The search then turned to vegetative systems. Of the 19 plant species tested only Vetiver grass was selected and developed to an effective soil and water conservation system. This system was very practical and easily implemented (Fijian agricultural systems being labor intensive rather than mechanized) and very effective as a soil conservation measure. Vetiver also conserved water increasing subsurface recharge as runoff water slowly seeped through the hedge instead of being diverted off the field. This greater accession to subsurface and ground water has probably led to productivity improvements and an improved overall water management system with greater stream persistence in the dry season.
CSR rigorously enforced this soil conservation technique on all sloping lands until the company left Fiji early in the 1970's. Since then this system has not been enforced under the present land use policy of the Government, despite steeper lands (up to 66% slope) being used for sugar cane production.
Official records show that the first Vetiver contour hedge was established in 1952 in the Penang Mill area, near Rakiraki, and hedges over 40 years old are quite common in the area, but farmers have used Vetiver for slope and batters stabilization for more than 50 years.
Current Application and Effectiveness of the Vetiver System in Fiji
Vetiver grass is widely used in Fiji from simple road embankment and stream bank stabilization, to contour hedges in sugar cane lands, and slashed and burnt plots on the east coast. it is a common practice for farmers to plant Vetiver to stabilize farm roads, across depressions, to spread and slow down runoff water, and most often on contour lines to protect their vegetable crops from rill erosion. According to local farm advisers of the Penang Mill, Rakiraki, 'Vetiver grass Systems' provide a very simple and practical solution to the soil erosion problem on small farms where both educational and technological knowledge is minimal and labor intensive activities dominate.
In all sugar cane growing areas, from the low slope fields around Lautoka to very steep hillsides around Rakiraki, terraces formed by Vetiver hedges up to 1.5 m high are quite common. These terraces were formed by soil erosion upslope and subsequent trapping by Vetiver hedges downslope over a 25 - 40 year period. The spacings between hedges are relatively close (averaging 30 - 40 m apart). The quantity of soil eroded and then trapped by the Vetiver hedge to form these terraces clearly demonstrates the effectiveness of the Vetiver hedge systems and the huge soil losses that would otherwise have occurred off those steeply sloping lands.
In general, fields protected by Vetiver hedges often have higher productivity than those unprotected by the hedges. On the average, where the practice is used on steep cane lands in the Rakiraki region, good yields can be expected for up to 7 to 8 ratoon crops. The number of ratoon crops in unprotected fields is generally lower and yields are reduced. Farm advisers attributed the loss of production to both soil and water losses on unprotected fields. In a simple demonstration trial, sugar cane yield of 48 tons per ha from a field protected by Vetiver hedges, and was reduced to 31 tons per ha from unprotected fields. This represents a 55% loss in production.
With the clearly demonstrated benefit of the Vetiver hedges in existence for the last 40 years, it is of interest to note that Vetiver has not become a weed. In addition to the provision of thatching materials, farmers still are very reluctant to establish new Vetiver hedges. In some cases they have removed old, well established hedges, resulting in massive soil erosion and drastic reduction in yield and within a few years the once productive land was covered with weeds and stones. Reasons given for these actions varied but the central theme pointed to these three concerns:
· Vetiver hedges take up too much land;
· terraces formed by the hedges hinder farm machinery operation; and
· the hedges sometimes harbor pests such as rats.
On closer examination, the real reasons are probably more complex than these three superficial concerns.
1. Land shortage. After 40 years where hedges were not properly maintained, the single row of Vetiver spread from 0.3 - 0.4 m to more than 2.5m width. Depending on the land slope and the original spacing, cropping areas sometimes were reduced to 4 - 5 m between hedges. In addition the trapped sediment formed terraces up to l.5 m high, hindering farm machinery operations. As with other developing nations, Fiji is faced with a severe shortage of agricultural lands, so it is obvious and understandable that farmers are concerned about the loss of productive land, where the cropping area of an average sugar cane farm is only 4 ha.
2. Land ownership. In addition to land shortage, land ownership is also an important issue. Under the present system, most Fijian farm lands belong to the Native Land Trust Board which administers the lease of the land to farmers for agricultural use. As the case of most lease land, farmers are not often very receptive to long term soil conservation measures where benefits are not often apparent in the short run.
3. Land use policy. Under the CSR policy, sugar mills enforced strict land use guidelines. Mills only accepted sugar cane from farms that implemented soil conservation guidelines recommended for the districts. For example, Vetiver hedges system was recommended for farms with land slopes of 12% or more. The spacing of the hedges was determined by soil type and land slope. Under the present Government policy sugar mills cannot enforce these guidelines, and farm advisers can only "advise" farmers to implement soil conservation measures which are often ignored, the few exceptions being new farmers where soil conservation and other agronomic advice is well received.
4. Inflexibility of the existing system Although the present system still provides a very effective water conservation method, it was designed over 40 years ago when the main power source was draught animals. As farming practices have increasingly relied on modern technology, including farm machinery, the existing system in general can cause hindrance to farming operations. For example, draught animals can walk around or climb over an overgrown hedge and terrace, whereas tillage and harvesting machinery can not. Redistribution of trapped sediment upslope is a major task, if it is done manually but with the availability of tractors the job can be carried out much faster.
5. Lack of development and extension support. There has been very little support to assist farmers in overcoming problems associated with the implementation of the Vetiver hedge system. The three major concerns expressed by farmers, namely the loss of productive land, hindrance to machinery operation and harboring pests, can be all resolved if an effective hedge maintenance program was carried out. If the hedges were trimmed and accumulated sediment was redistributed every few years, the spreading of the hedges and the build up of terrace would be very effectively controlled. As a result of the above actions, thin and well trimmed hedges are less likely to harbor rats and other pests. In addition, the general extension effort regarding the benefit and impact of a soil conservation system such as Vetiver hedges has been very limited due to the shortage of well trained extension staff.
In summary, the pitfalls DON'TS listed above range from technical (Research, Development and Extension) to political (Land Use policy) and socio-economic issues (land shortage and ownership).
From the above summary it can be seen that solutions to these shortcomings range from fairly simple technical issues to complex socio-economic ones which require both economic resources and political will. While some of these can be solved satisfactorily, others will be slow and difficult to solve and those, which involve cultural, ethnic and political issues probably can never be resolved satisfactorily. However if these issues are known and properly dealt with now, most of the pitfalls mentioned above can be avoided.
If the Fijian experience can be used as a model, the following three issues deserve utmost and urgent attention:
Research, Development and Extension. The conventional engineering soil and water conservation systems such as contour and diversion banks, and waterways etc. have been adopted and implemented worldwide for a long time, but these systems still require continuing research, development and extension efforts to improve and to gain farmers acceptance. Likewise, a new concept and technology such as the Vetiver system will need these supports for a long time. Some of the topics that have to be taken into account are:
· Suitable cultivars. There are a vast number of different species, sub-species of the Vetiveria genus, and an enormous range of V. zizanioides cultivars that are grown worldwide. They should be screened and selected for various applications. The Thai Department of Land Development has done an excellent job in collecting and screening more than 40 Vetiver cultivars and species for regional applications, but it is suggested that they should go one step further by selecting suitable cultivars for different crops and applications. For example shade tolerant cultivars are needed for tree crop and orchards, tolerance to salt and heavy metal toxicities for land reclamation, non-seeding cultivars for agricultural crops, fast regrowth and tolerance to grazing pressure for pastures and rot resistance for thatching, just to mention a few. In short the selection program needs to be purpose-oriented.
· Propagation and Establishment. Although potting gives excellent results, it is slow and costly and should be limited to high value projects to ensure fast, reliable establishment and growth. Direct planting is the method farmers would prefer, and it should receive full research, development and extension attention. Detailed guidelines such as slip size, age, hormone treatment, soil moisture, seasonal conditions (rainfall and temperature). Obviously different guidelines are needed for different crops and applications.
· Maintenance. In. the long term, maintenance is the most important aspect which greatly influence the acceptance of the Vetiver by farmers. As mentioned previously the concerns expressed by Fijian farmers relate to the lack of a proper maintenance program. For example, for sugar cane crop, Fijian farm advisers recommend that hedges should be slashed twice a year, one early in the wet season to encourage growth and once towards the end of the wet or the beginning of the dry season to remove excess material which encourages rats. Trimming is required every 3, 4 years and trapped top soil should be spread up hill during replanting (5-7 years). Alternatively, every second hedge can be taken out, trapped top soil respread, and replant Vetiver with each cane replant cycle. The maintenance guidelines should also include recommended methods of controlling unwanted Vetiver plants. Again maintenance programs need to be developed for each application.
· Design layout for various crops and applications. Design layout should be flexible enough to take into account different cropping practices and regional variations. Wherever possible likely future changes in practice and crop production should also be considered. In addition, having understood the function and potential of Vetiver hedges, its applications should be extended to other non-conventional areas, both in agricultural and non agricultural sectors, such as mine rehabilitation, water quality improvement and toxic wastes management. A good example of a further application in soil and water conservation, the Thai Department of Land Development work on the incorporation of Vetiver into a Leuceana-pigeon peas alley cropping system and water harvesting design for fruit trees in Chiang Rai.
· Extension. An extensive extension service is needed to ensure long term success. Extension staff should not only be competent in soil erosion and sediment control matters but also in the agronomy, tolerance and adaptability of Vetiver grass. But most importantly, the final application and layout should be a compromise between farmers' needs and the recommended standard design.
Land Use Policy. Lessons drawn from the Fijian experience strongly indicate that a firm land use policy is required for long term success. As pointed out above, when CSR was responsible for a large part of the sugar industry in Fiji in the 1950's strict soil conservation guidelines were applied. CSR sugar mills only accepted crops from farmers that complied with the company guidelines. With well trained and a supportive team of farm advisers, farmers were happy to implement these guidelines and CSR was able to maintain the productivity of these highly erodible lands.
Land use policy guidelines need to be developed for each agricultural industry such as sugar cane, rice, horticultural crops, pastures etc. taking into account topographic, edaphic, rainfall erosivity characteristics as well as the farming practice of each region. When properly developed and supported by extensive extension/education program, most farmers would accept it. However, to be effective, legislative support is often required. For example, to obtain a contract to grow sugar cane on lands with slope exceeding 15%, farmers in southern Queensland, Australia, have to implement green cane harvesting, trash retention practices -- a soil conservation practice where the crop is mechanically harvested unburnt and retaining the trash all year round.
Land ownership. This involves' the highly volatile socio-ethnic-economic-political issues associated with any land reform program which require firm commitment from political leaders. It will be slow and difficult, but it should be considered as a long term goal. People will be more willing to take better care of properties they own, particularly in societies where land ownership is linked with cultural and spiritual values.
Although the Vetiver soil and water conservation system has clearly demonstrated its effectiveness and benefit to the sugar industry in Fiji, its acceptance by farmers is not guaranteed. To ensure its long term success, continued input into the development and adaptation of the system to changing needs of various agricultural industries is required.
Truong, P.N.V., Creighton, C. (1994). "Report on the Potential Weed Problem of Vetiver Grass and its Effectiveness in Soil Erosion Control in Fiji". Division Land Management Report, Queensland Department of Primary Industries, Australia.