3.1 Objectives
3.2 Elements
3.3 Agroforestry systems
3.4 Costs and benefits
Agroforestry is not restricted to marginal areas, but develops its full potential on fertile soils. Traditionally, multistorey agroforestry systems were practised in the alluvial plains of Dominica's rivers. In the last years, new interest in agroforestry arose from environmental concern:
# 16,000 ha with moderately high erosion risk can be cultivated sustainably only with tree crops and silviculture# the expansion of banana cultivation to unsuitable land caused severe erosion and the loss of top soil
# the destruction of virgin rainforest due to the loss of fertility of cultivated land
# the cutting of forest cover and the indiscriminate use of agrochemicals endangers the nation's watersheds, damaging ultimately also the marine life in the coastal zone
# in some regions the availability of firewood decreased after years of high consumption for distillation and charcoal production
These concerns required the elaboration of agroforestry projects and programmes in the process of the Tropical Forestry Action Programme.
On the other hand, the social and economic context plays an important role in the definition of the objectives to be considered of importance in the introduction and development of agroforestry systems in Dominica:
# soil conservation
# watershed protection
# reduced risks of hurricane damages
# long-term improvement of soil fertility
# improvement of microclima
# lower incidence of pests and diseases
# reduction of external inputs (fertilizer, pesticides)
# increased total output/acre
# diversification of production
# reduced dependence on instability of commodity markets
# diversified supply for home consumption
# annual labour distribution
# production of non-food-products (timber, firewood, fodder etc.)
# maintenance of landscape beauty and natural diversity
# development of cultural traditions and experiences
These objectives are in accordance with the strategies of agricultural development as outlined in the Agricultural Sector Plan 1991-1994, which aims at deepening inter-relationships and complementarity among Agriculture, Industry and Tourism. In particular the following goals outlined in the Agricultural Sector Plan can be enhanced significantly be agroforestry:
# To improve the quality of life for the rural and general Dominican population.
# To foster economic stability through diversification
# To maintain the production potential of agricultural resources and to preserve the environment (Commonwealth of Dominica 1991, p.17)
It can not be expected that merely by the promotion of agroforestry techniques all of the above mentioned objectives will be reached. However, agroforestry can give a major contribution if the legal, political and economical framework conditions favour agroforestry systems with diversified production systems and conservation measures. Especially action in land use regulations, marketing and reorganization of the system of agricultural incentives is required to establish such favourable conditions (see recommendations 5.3 - 5.6 and reports on Legislation and Land Use/Watershed Management).
Depending on the farmer's individual objectives, agroforestry systems in Dominica should include one or more of the following elements:
# contour hedges composed of leguminous trees or West Indian cherry with vetiver grass as soil conservation measure# windbreak plantations
# shelterbelt plantations along streams and on farm borders
# different cash crops (fruit trees, bananas, coffee, cocoa etc.)
# crops for home consumption (root crops, vegetables etc.)
# live fenceposts and support for pass ion fruit
# firewood and timber species
# fodder trees
These elements can be combined in innumerous systems, depending basically on
- farm size
- available labour
- soil and clima conditions
- slope
- individual preferences
- marketing structures available to the farmer
- need for firewood and other raw materials.
Generally the farm size will be the most important factor to determine the system. Smaller farms are cultivated more intensively than bigger farms, annual crops are more important in these farms and a higher degree of diversification is required.
* Traditional systems
In Dominica multi-story-planting, generally composed of coconut or citrus - bananas - (coffee/cocoa) - root crops has been a traditional system used for centuries by small farmers as well as on big estates. Also windbreak plantations and live fenceposts are traditionally used, but in the last decades a high percentage of these tree components were destroyed in favour of the expansion of banana cultivation. Between 1966 and 1988 on Castle Bruce Estate banana cultivation expanded from 700 to 900 acres, while oil palms and citrus trees were cut down. (James 1989)
Nevertheless, traditional agroforestry systems are still in practice in the Carib Territory and other sites and can be improved by the introduction of
# leguminous scrubs and grass in contour hedgerows for coppicing and mulching or animal fodder# contour hedgerows of West Indian cherry (spaced 2 ft within row)
# grafted varieties of mangoes and avocados
# plants for live fenceposts
# the combination of passion fruit with living support trees such as gliricidia and leucaena
# cash crops other than banana: coffee, cocoa, aloe
# the integration of livestock (goats and pigs) to use cut fodder and surplus fruits and to produce organic manure
# communal marketing facilities for different commodities to support diversified production systems
* Agroforestry elements in existing banana plantations
In the past extension recommendations of WINBAN did rather enhance pure stand banana plantations, but in the last years some research was realized on multiple cropping. Regarding the extension of banana cultivation in Dominica (13,000 acres) and the ecological problems caused by it, an important issue is to introduce agroforestry elements in existing banana plantations:
# contour strips to reduce soil erosion# windbreak plantations and shelterbelts to reduce damages by high-velocity winds and create a better microclima, increasing the production, especially on the windy east coast
Further elements recommendable for banana fields, especially on steep slopes are:
# tree intercropping (coconut, citrus, avocado or forest species), using larger spacing than in orchards (40 x 40 ft. or more)# intercropping of coffee or cocoa
# ground cover (preferably herbaceous leguminosae)
These measures can result in
- a long term diversification, regarding the end of protective policies for bananas in the U.K. in 5 years. After some years the banana population might be reduced from 700 to 400-500 plants/acre or totally replaced to give space to the developing tree crops.- in the reduction of rain impact on the soil and reduced soil losses,
- reduced leaf spot disease caused by higher tree stories
- reduced population of soil nematodes by respective groundcover (especially stizolobium sp. = mucuna sp.)
- reduced need of weed control
* Cocoa based systems
In regions below 1000 ft. altitude the intercropping of cocoa (spaced 16 x 8 ft) in combination with permanent shade trees as breadfruit or coconut (spaced 30 x 30 ft. or more) in existing banana stands seems an interesting combination for farmers with the intention to diversify. Cocoa can guarantee a secure income after 3 years and market prices will determine if farmers cut down their banana plants after 3-4 years or maintain them. It seems that presently cocoa can produce a yearly income than bananas. This advantage increases when profitable fruit trees are intercropped. This system could be used in the fertile river valleys of both coasts.
* Utilization of marginal steep lands
On marginal steep lands specific systems are necessary if soil productivity is to be sustained, including contour strips composed of legume trees and vetiver grass, mulching (coppicing the legume trees) and plantation of tree crops which stabilize the soil and reduce the impact of rainfalls. In high rainfall areas floriculture with anthurium under trees is highly profitable and provides a good permanent groundcover which effectively controls erosion. Anthurium prefers 60 % shade and therefor is an interesting crop for agroforestry under dense canopies. Transport by air freight to overseas markets is available from Melville Hall Airport. In the steep lands of the Southeast, where bay oil is produced, legume trees for firewood can be combined with fruit or bay trees.
* Traditional systems
Traditional agroforestry systems have many components, for home consumption, sale, fodder and other uses. They tend to be adapted to the farmer's family's labour potential and its basic needs. Improvements of these systems will be implemented gradually, according to the farmer's time. Costs for the establishment and maintenance of contour hedgerows will be the same as in the case of hedgerows in banana plantations described below.
* Agroforestry elements in existing banana plantations
Costs for the establishment of windbreaks and hedgerows (including Vetiver) in 1 acre of banana plantation can be estimated as follows:
|
667 plants x 1.5 EC |
1000 EC | |
|
67 plants x 3 EC |
201 EC | |
|
transportation |
150 EC | |
|
labour - lining 1 manday |
30 EC | |
|
|
- planting 7 mandays |
210 EC |
|
total |
1591 EC | |
Costs for maintenance are basically coppicing twice a year and can be estimated at 7 mandays/year = 210 EC
Benefits as animal fodder, nitrogen fixation, soil conservation have not been calculated so far, but result can be expected from agroforestry research (5.5)
* Cocoa based systems
Benefits of agroforestry systems might be compared with the predominant banana cultivation which creates an average net income of 2000 EC$/acre. Cocoa production can produce a net return of 3000 EC$/acre. However, farmers prefer weekly cash income as created by bananas to seasonal income as in the case of cocoa and most fruit trees. Passion fruit and papaya might be alternatives to bananas in this respect, as they produce fruits during most of the year.
Farmers have no costs for the establishment of cocoa plantations except labour costs, because the Cocoa Project gives plants and inputs for two years to the farmers free of charge.
* Utilization of marginal steep lands
The establishment and maintenance during the first year of 1 acre of firewood plantation in alternate rows with tree crops causes the following costs:
|
335 seedlings x 1.5 EC |
|
502 EC | |
|
50 fruit tree seedlings x 3.5 EC |
|
175 EC | |
|
transport |
|
100 EC | |
|
fertilizer, fungicides (?) |
|
80 EC | |
|
labour - land preparation (strips only) |
3 mandays |
90 EC | |
|
|
lining |
1 manday |
30 EC |
|
|
planting |
3 mandays |
90 EC |
|
|
maintenance (1st year) |
4 mandays |
120 EC |
|
total |
|
1187 EC | |
|
farmer's contribution (1 EC/fruit tree, labour) |
|
350 EC | |
Maintenance costs are increasing in the following years:
|
|
2nd year |
3rd year |
4th year |
5th year |
|
inputs |
100 EC |
200 EC |
250 EC |
300 EC |
|
labour (weeding, pruning etc.) |
270 EC |
270 EC |
270 EC |
270 EC |
|
total |
370 EC |
470 EC |
520 EC |
570 EC |
Costs are lower on fertile soils where no fertilization of mangoes is required. Within the Tropical Fruit and Spice Project inputs are free for 4 years, so the farmer's contribution will be limited to labour during this period.
Harvesting costs of firewood are considerable, but depend largely upon the distance between the plot and the final destination (distillery, bakery). Generally, firewood has to be delivered to a road accessible by truck.
Harvesting costs for the fruit trees will begin only in the 4th year and increase with growing yields:
|
|
mango |
avocado |
|
4th year |
120 EC |
120 EC |
|
5th year |
180 EC |
240 EC |
|
6th year |
300 EC |
360 EC |
|
7th year |
420 EC |
480 EC |
|
8th year |
570 EC |
600 EC |
|
9th year |
680 EC |
720 EC |
|
10th year |
780 EC |
720 EC |
(labour costs were calculated at 30 EC/day of 5 hours)
Yearly raw income from this system will be approximately 600 EC from their sale of 8 cords of wood and between 2000 and 10,000 EC from the sale of fruits when the trees have reached full production, depending primarily on the marketing facilities available to the farmers.
