Fuel wood is the most common source of household energy for both rural and urban households in ASAL. Moreover charcoal production as an economic activity is nowadays widely practiced. Charcoal production activity which targets the big trees that have been growing for the last 20 to 30 years is expanding these days. This could reduce the vegetation cover of the already fragile ecosystem. Yet there is no any meaningful plantation going on to replace those trees cut for different purposes including charcoal making.
Conservation (protection) of natural vegetation and plantation activities can simultaneously be implemented in ASAL. Conservation of exiting trees and shrubs could be achieved through awareness raising and creating and enforcing community bylaws. It was indicated earlier that planting of trees by communities is not common in ASAL probably due to community’s pastoral way of life; there has been no any meaningful support provided either. However, with the introduction of water harvesting technologies (negarims, micro-basins, trapezoidal bunds, etc) trees can be planted at manyatta areas and along (ephemeral) rivers and gullies. Combining rainwater harvesting technologies and tree planting will enhance seedling survival rates especially during the dry period.
Thus developing nursery sites for the production of drought tolerant multipurpose plant species is very important activity. This activity will increase income generating opportunities and contribute to resilience building and environmental protection. Besides other factors the availability of water is a precondition for establishing nursery sites. The activities in these nurseries can be managed by group of people mainly women groups and should be linked to homestead and riverin development initiatives. These development sites should be fenced (dry or green fencing) with locally available materials to reduce livestock interferences. Seeds can either be collected locally by using food for work or purchased from elsewhere. Training should be done on nursery management (tools and seeds handling, seedling transplanting, watering, weeding, grafting, pruning, seeds scarification, soaking, compost making, etc.). Table 14 Gives names and uses of some tree, shrub and grass species suitable for ASAL condition. Seeds can either be collected locally or purchased.
Table 14. Suitable trees and shrubs suitable under ASAL condition.
Site selection - Success or failure of a tree nursery depends on the suitability of the selected site. Factors to consider are plot area, water, soil, topography and access:
Area required - Depends on the number of seedlings to be raised and the production system. For Chiefs Nursery/School Nursery aimed at producing 50,000 plants per season require 25 m x 25 m (625 m2) area. More specifically to raise 1000 forest/fodder trees only 4.5 m2 land is required. But to raise 1000 fruit trees just 8.5 m2 is sufficient. Above is minimum area required in starting a nursery but additional space for foot paths, store, working area, etc are required.
- Seedlings have to be watered once or twice daily.
- Quality of water is important; it should not be saline and should be of neutral PH.
- Distance between the water source and nursery is important.
- Water requirements for nursery stock will vary with location of the nursery, time of the year, stage of seedlings and production method.
- Thumb rule - potted stock requires about 5 to 10 mm per day.
- Equivalent to 5 to 15 liters of water per m2 of nursery bed per day
- Soil is the growing medium for all plants
- Good soil must be available within the nursery or close at hand.
- Soil requirement: for 10,000 seedlings in 4x6 inches tubes is about 5 m3 of soil; for 2000 fruit seedlings 5x9 inches bags – 3 m3
- The soil used, must be light and freely drained and must as well have capacity to retain moisture.
- Bare-root seedlings utilize the soil already in the nursery.
- Best site should be 3 -5% slope to allow ease of drainage of excess water without causing erosion. If the site is flat there is risk of flooding and appropriate drainage must be put in place.
- Site – steeper slope must be terraced.
- Access and fencing
- A nursery must be close to the area where the seedlings are to be planted and suitable for evacuating seedlings.
Fencing and windbreaks
Once the nursery site is established fencing is done using live fence or wire mesh but be advised to plant hedge around the nursery. The species include Leucaena, griliricidia, camiphora, etc.
A well designed windbreak will protect the nursery from strong winds and reduces evaporation losses. It provides a favourable micro climate to the seedlings and protects young seedlings from damage and promotes better growth. Windbreak also creates good working environment for the people working in the nursery. Windbreak should aim at reducing wind speed by 50%. Prosopis species, Azadirachta indica (Neem), Acacia scorpioides, Leucaena leucocephala, Parkinsonia aculeate, etc. can be used for windbreaks in ASAL.
· Soil in the seedbed should be freely drained, light clay and contains good amount of sand
· Width of bed should be 1 m to 1.2 m but can be length of any length
· In clay soils - drainage must be improved by digging a 0.4-0.5 m deep formulation a layer of stone laid (0.20-0.25 m) and filled up with sand
· Seedbed surrounded by blocks of stones or timber to support the soil
· Polytubes planted with seedlings are arranged in a proper order
· Root pruning of young seedling is a laborious but necessary job
· A sheet of black polythene is usually laid on the ground to prevent roots from growing into the soil beneath the tubes or bags
· A layer of 1-2 cm coarse sand above the polythene sheet will retain moisture while protecting roots from fungi attacks
· Drainage system should be put in place, which can be opened and closed
· In dry areas, beds should be laid below ground level (sunken bed). Sunken beds should not go below 5 -10 cm below ground level
· But raised bed can be used where floods occur to avoid water digging
· In both raised and sunken beds the walls should be stabilized with stones or cut of timber.
Access and paths: Access should be planned for during the initial layout. Paths between nursery beds should be between 60 and 80 cm wide to ensure ease of mobility.
Shade: Young Nursery stock requires shade during the establishing period. Shade could be provided by a large trees or simply thatched house. The shade could be permanent or semi permanent. A permanent shade is structure where potted nursery stock is placed during first few weeks after transplanting and is at least 2 m high. A permanent shade covers several beds. A semi-permanent shade covers a single bed and is placed about 60-90 cm above the seedlings. Structure for semi-permanent shade is made by wooden sticks and covered by grass or branches. When no longer needed, the shade is removed.
Sowing the seeds and weeding: Care should be taken when packing the seedlings and delivery to planting site. Generally seeds should be planted in a fine seedbed at depth of 1 to 2 times its diameter. After germination regulate seed density to maintain vigor and appropriate size of the seedlings. Care of seedlings in the seedbed should ensure that good healthy seedlings are planted. Weeding should be done regularly.
Water supply: Water can be applied using either watering cans or irrigation canal. Irrigation canals lead water to the nursery and nursery beds by gravity. Water demand can be determined as follows: for seedbeds (seeds not yet germinated) water application rate can be as low as 5 mm per day. This means that 5 liters of water is required to irrigate 1 m2 of seedbed. But for nursery beds (after germination) one application per day of 10 mm (10 litres per m2 of nursery bed) is recommended. Quantity of water required can fluctuate, depending on local climatic conditions, stage or the seedlings, the species and other factors.
A wide variation of worknorms are expected if computed based upon type of trees to raise, access to water, etc. However, a realistic average should be found. Different organizations allocate individual worknorms for each element of seedling production activities which is relevant at nursery site for monitoring of day-to-day activities by a nursery foreman (see Annex 2). For example one can approach in such a way that 1 person fills 100 poly pots per day. However, for planning purpose at national and provincial levels a computed (sum) worknorm is required. For example in Burundi 20 person days are required for producing about 1000 seedlings.