- Coffee
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- Eucalyptus
RPN is also propagating eucalyptus hybrid clones for fast-growing, high-yielding plantations.
Why Go Clonal?
- Increase growth rate
- Superior vigour
- Apical dominance for sawn log production
- Increase timber volume
- Superior timber qualities
- Pest and disease resistance
- Drought tolerance
- Suitability to specific soil types
- Suitability to specific climate zones
- Salt tolerance
- Eucalyptus varieties propagated at RPN
- GU8
- GU7
- GC 550
- Average rainfall of 1200 – 1450 mm
- Temperature range 7.5 – 30
- Altitude range 621 – 3962 m
- Macadamia
Growing Macadamia
There are two types of Macadamia nuts grown commercially in the world today. These are Macadamia integrifolia (smooth shelled type) and Macadamia tetraphylla (rough shelled type). Macadamia is the most popular nut in the world today. It is increasingly becoming a major cash crop in East and Southern Africa and Latin America.
Feasibility studies made in Uganda in 2003 indicated that there is a very high potential for the crop as the country has adequate rainfall, suitable soils and elevation similar to that of Kenya.
Macadamia trees grow slowly to heights of 12 to 15 metres. They have shiny dark green leaves, and bear sprays (racemes) of long, delicate, sweet-smelling white or pink blossoms. Each spray of 40 – 50 flowers produces from four to fifteen ‘nutlets’ which will eventually ripen into nuts.
The nuts themselves grow encased in a hard, woody shell, which is protected by a green-brown fibrous husk. In its natural state, a macadamia tree will have flowers, nutlets and mature nuts growing simultaneously in profusion, for much of the year. The nuts fall to the ground for harvesting at regular intervals.
Climate Range
Macadamia grows well between 1200 – 1850 m above sea level in the East African highlands but is grown at relatively low altitudes in South Africa, Australia, Hawaii, California and Australia.
The optimum temperature for the crop ranges from 15 – 28°C. Avoid areas that experience frost. Macadamia requires a minimum annual rainfall of 1000 mm. The rainfall can be supplemented with irrigation (where need be).
Soil Type and Site
Macadamia needs well-drained fertile soils with enough depth to permit good root development. The soil should be at least 100 cm deep. The optimum soil pH range is 5.0-6.0. After choosing a suitable site, it is recommended to establish wind breaks especially in the areas with strong winds.
Land Preparation
The land should be prepared well in advance during the dry season. The first and second ploughing should be done followed by harrowing. The land should be well prepared (i.e. fine tilth).
Propagation
Only grafted seedlings of selected varieties which are suited to the various climatic conditions should be planted e.g. KRG-15; EMB-1; MRG-20; KMB-3 etc. Seedlings obtained directly from seeds have low yields of poor quality and therefore should never be used.
Spacing (Layout)
The planting distance depends on the topography and the land use e.g. inter-cropping. Currently the recommended spacing is 7.5×7.5m (75 trees /acre) to 10x10m (45 trees per acre).
Transplanting
The planting holes should be dug during the dry spell. The topsoil and the subsoil should be kept separately. Fill the hole with the topsoil mixed with 2 tins of well-decomposed manure. The transplanting is more successful when carried out during the long rains.
Open the seedling containers carefully making sure that the soil covering the roots remains intact. Place the seedling in the hole. Fill the holes firmly with the topsoil. Make a basin around the seedling for holding water. If the soil pH is below 4.5, liming may be necessary.
Staking
Staking of the seedlings should be done immediately after transplanting where there are strong winds.
Care of Transplanted Seedlings
The most critical stage for the young trees is between 3-4 years after transplanting. The following cultural practices should be carefully carried out.
- Watering
The trees are sensitive to both water logging and water stress. Therefore watering at least once or twice a week (using sprinkler or drip irrigation) should provide adequate moisture.
- Mulching
This helps to maintain soil moisture, improve soil fertility and suppress the weeds. The mulch should be placed at a distance of 10-15 cm from the base of the tree. Commonly used mulches include coffee husks, sisal waste, grass and banana leaves.
- Weed Control
Weed control around the tree is essential to avoid competition for water and nutrients. An area 1.5 times the size of the tree canopy should be kept free of weeds. Hand weeding or chemical weed control using herbicides is recommended. Slashing between the rows should also be done.
- Training and Pruning
The purpose of training is to develop a tree with a strong well-balanced frame for future growth. Untrained trees usually tend to produce several leaders and branches are unevenly spaced along the trunk. Such trees are very prone to breakage by the wind.
The most satisfactory form is a low branching tree with only one trunk or leader and several sets of main branches forming wide angles with the trunk. The trees must be trained within three years of transplanting in the field.
Macadamia requires little pruning. This involves removing broken, split or dead branches. The branches should be cut back close to the laterals or the main trunk. Experiments are being conducted to establish the effects of various pruning and training methods on the growth and productivity of the macadamia tree.
- Intercropping
The objective of intercropping macadamia with other cash/food crops is to increase the gross margin/unit area and to obtain maximum utilisation of the land.
- Possible intercrops
The following crops can be used for intercropping with macadamia i.e. French beans, Vegetables, Lucerne, Green peas, Common bean, Passion fruits, Ornamental flowers, Irish potatoes and Groundnuts.
Note: As macadamia approaches the 15th year, there is normally no need for intercropping. This is because the farmer is getting maximum returns from their macadamia trees.
- Harvesting
Harvesting of macadamia nuts is done by collecting the nuts, which have fallen on the ground. This is done within 2-3 days to prevent deterioration or damage by rodents. Picking nuts from the trees is strongly discouraged. This is because it is not possible to distinguish mature nuts from immature ones, while still on the tree.
During the peak harvesting period, nuts should be collected at 1-2 days intervals depending on the weather and the number of the fallen nuts. For efficient collection, the area underneath the canopy should be maintained free of weeds or any dry leaves so that nuts are clearly visible.
Pests and Diseases Affecting Macadamia
Macadamia does not have many pests or diseases. In Uganda (and other small-scale holder farmers), no pests or disease control is necessary. However, under extensive cultivation at low altitudes, Macadamia stink bug (Bathycoelia bequarti Schouten) has been identified as a major pest.
The infested kernels generally become spongy with or without brown pit-like depressions. Such kernel shrivels, become soft, distasteful, and acquire translucent appearance unlike the normal white appearance.
Control
Biological Control
The population of B. beguarti is controlled naturally by a number of egg parasitoid wasps. These are Tetractrichus spp, Tamarixia dryi, Approstocetus spp and Anastatus spp. These wasps can control about 55% of the stinkbug.
Chemical Control
Fenitrothion at 1 ml/L water application during the initial fruit formation stage is effective in large-scale orchards.
Post Harvest Handling
Dehusking
This is the removal of the outer green covering of the nut after dropping from the tree. This should be done within 2 days of harvesting and the nuts should not be heaped or stored in sacks.
If they cannot be dehusked immediately, they should be spread on trays or floors sheltered from the rains in layers of six to seven centimetres to avoid mould infection. The husk material is usually recycled as organic mulch, and the ‘nut-in-shell’ (NIS) is generally sent to a commercial processor.
Drying
Careful drying is a critical step in macadamia processing to maximise shelf life and quality of the end product. At harvest the nuts have a moisture content of up to 30%. Drying can take up to three weeks and reduces the moisture content to around 1.5%. The kernel shrinks away from the inside of the shell and allows the shells to be cracked without damaging the kernel.
In shell nuts can be air-dried in the shade. Drying should not be under direct sun as this causes the shell nuts to develop cracks. These cracks serve as entry points for fungi and other organisms, which cause deterioration of the kernels.
4. Mangoes
ENVIRONMENTAL REQUIREMENTS
No specific soil type as long as it’s well drained.
- The optimum PH range is between 5.5 – 7.5
- Rainfall: mangoes are drought resistant and require at least 300 mm of rain per annum. The best climate consists of 4 months of rainfall (750 – 2500 mm) followed by 8 months of dry season.
- Altitude: it does well at elevation between 0 – 915 m above sea level.
- Optimum growth temperature 75 – 80 degree.
- Spacing should be 12m x 12m.
5. Oranges
- Citrus grow well in tropical regions.
- An ideal citrus soil should be well structured, with good drainage to allow proper root aeration and minimise root diseases. Citrus prefer well-drained soils with a pH of 5.5 to 7.0 and low salinity.
- Citrus orchard spacing is 6m by 6m.
Hole: 2ft by 2ft by 2ft. Top soil should be separated from subsoil. At least 20 kgs of farmyard should be mixed with the top soil and returned to the hole for planting.
Varieties available at RPN: wash tone novas, Valencia, American tangerine and armly.
