Calliandra calothyrsus is a small, leguminous tree with characteristic pink flowers. It grows in a wide range of climatic and soil conditions, from the sea level to the highlands, but it performs best in coffee zones. Acidic soils, waterlogging and frost affect its growth and its economic benefits can be realized in the first year of planting. The tree can produce fodder continuously for more than 10 years. It can be grown in various sites on the farm since it does not compete with crops growing adjacent to it, as long as it is properly managed to reduce the shading effect.
Why grow calliandra?
There are at least six good reasons for growing calliandra in your farm-
High quality fodder supplement for livestock
Calliandra improves milk production of both dairy cattle and goats. It can also be fed to other types of livestock such as sheep, rabbits and chicken. A cow needs to be fed with roughly 6kg of fresh leaves per day, a goat about 0.7kg. to harvest 6kg fresh leaves every day, you need to plant 500 calliandra trees at a spacing of 0.5m (1½ ft), making 250m (800 ft) of hedge. This seems like a lot but a farm of 1 hectare (1½ acres) has over 400 metres (1280 ft) of external boundary, plus additional sites (along internal boundaries, along contours, around the homestead) where calliandra can be planted.
Calliandra, being a leguminous species, has root nodules that fix nitrogen from the air. This fixation process helps in improving soil fertility because nitrogen is one of the most important nutrients for plant growth. Animals fed with calliandra produce high quality manure.
Stabilizing soils and water conservation structures
Calliandra has a deep root system. When planted along soil conservation structures, it plays a significant role in holding the soil together. It performs well in soil conservation when planted adjacent to lines of napier grass on “fanya juu” and “fanya chini” terraces. The trees need to be planted at a closed spacing of 0.5 metres (1½ ft). They should also be 0.5 metres above the napier line.
Seed production and bee forage
It is advisable that you preserve some calliandra trees for seed production so that you will not need to rely on external sources for future planting. The same trees provide excellent bee forage, so you have additional benefit of honey production. Leave one tree uncut every 20 metres (about 20 steps) and make sure the total number left is more than 30. This improves the chances of cross-pollination and ensures that the seeds produced are of high genetic quality. In case you leave less than 30 trees, exchange seeds with neighbors and mix seeds from different sources before sowing.
If left to grow uncut, calliandra produces quality fuelwood. The wood burns better and has less smoke if left to dry well before use.
Stakes for climbing beans and tomatoes
Stakes produced by calliandra are good support for other plants such as climbing beans and tomatoes.
Establishing your calliandra nursery
Locate your nursery near a reliable water source such as a river, a spring, a borehole, a dep well, or reliable piped water. Ensure that the nursery has access to water throughout the 3 – 4 months it will be in use.
The seedbed should be about 1 metre (3 feet) in width and can be as long as the available space allows, but 3 metres is the usual length. A path of 0.6 metres (2 ft) should be left between two adjacent seedbeds for ease of access to both beds. A bed of 1 x 3 metres can produce 400 seedlings.
After you have decided on the nursery area, apply manure to the beds at the rate of 1 part of manure to 4 parts of soil; this translates to 1 “debe” of manure for every 3 metre length of the nursery. Mix the soil and the manure well.
Pile up the soil and manure mixture to make a raised seedbed with a height of about 10 – 15 centimetres (4 – 6 inches), and then level the soil.
Support the sides of the bed with materials like banana stems, timber or stones and prop them firmly with wooden pegs or stones.
It is very important that the bed is level and texture of the soil is fine, so as to increase the rate of seed germination.
Sowing calliandra seeds
A seedbed of 1 x 3 metres produces about 400 seedlings and requires 40g of seed. 1½kg is sufficient for planting a nursery bed 40m long. This bed will produce about 5300 seedlings, enough to feed 10 cows. This means that 100g of seeds would need a seedbed of about 7.5m that can produce approximately 1000 seedlings, adequate to feed 2 cows.
To ensure good germination, you need to soak the seeds in cold water for 2 days (48 hrs).
Make a furrow about 2cm (1 inch) deep in your bed for accurate sowing. Place the seeds in the furrow and cover them lightly with soil. Space the furrows 10cm (4 inches) apart, and leave 5cm between seeds within the furrow. Avoid putting the seeds too deep into the soil because this will make them rot.
Water the bed thoroughly immediately after sowing. You can use a watering can, perforated tin or leafy branches. If termites are not a problem in your area, cover the seedbed with dry grass until the seeds germinate.
If you can afford tubing materials, remove the seedlings after they produce 2 leaves and plant them in tubes filled with soil mixed with manure at the same rate as that for raised beds. Using the tube is an extra cost, but it improves the survival rate of the seedlings, especially if there is shortage of water.
It is important to have a level nursery bed and fine soil texture, so as to improve on seed germination.
Use your hand to estimate distances if you do not have measuring equipment. For example, the width of the palm is about 10cm (4 inches) and the length of the first digit of the pointing finger is about 2.5cm (1 inch).
Applying Rhizobium inoculant
As with beans, calliandra roots have the ability to join with Rhizobium to form root nodules that fix nitrogen.
In most cases the Rhizobium population in the soil is not enough to form adequate amounts of root nodules for nitrogen fixation. It is therefore important to get Rhizobium from external sources.
The inoculant can be applied to calliandra seeds or young seedlings. For seedlings, mix the inoculant with water in a bucket and stir thoroughly using a stick. A packet of 200g of inoculant can make a solution of 60litres, which is enough for 40 metres of nursery bed in which about 500g of seed has been sown. Water the seedlings thoroughly before applying the inoculant in the soil. Apply the Rhizobium using leafy branches, repeatedly dipping them into inoculant solution and shaking it off on the seedlings.
If the inoculant is to be applied to seeds, mix it with water to make a solution. Mix the pre-soaked seeds with the solution and sow immediately avoiding excessive exposure to heat and light.
If the Rhizobium is obtained from the soil beneath mature calliandra trees, scoop the topsoil and spread it on the nursery bed before sowing seeds. The Rhizobium will be incorporated into soil and will assist the plant to grow.
Rhizobium inoculants consist of microorganisms that are destroyed by heat and light, therefore it is best to apply it in the late evening.
The following management practices are recommended for calliandra seedlings to enhance their survival:
Carefully observe the moisture level in the nursery bed and water whenever it becomes dry. It is important to water the bed sufficiently (but not too much) in the first 10 – 14 days after sowing before the seeds germinate. The seedlings should never look limp from moisture stress or suffer from damping off because of excess water.
It may be necessary to water the seedlings twice a day – in the morning and evening – especially within the first 2 months after sowing the seeds. Use a watering can, perforated tin or leafy branches. Watering may be reduced to once a day, preferably late in the evening.
Shading the seedlings
Make a shade structure 1m in height and cover lightly with grass or tree leaves ensuring that some light passes through. Avoid using branches from eucalyptus tree since its fallen leaves inhibit germination of other plant species. As the seedlings grow, gradually reduce the shade to get the seedlings used to full sunlight.
Remove all types of weeds as soon as you notice them to ensure better growth of the calliandra seedlings. Never allow your seedlings to be choked by weeds.
Protection against pests
Pests like crickets, grasshoppers and cutworms can cause heavy losses of seedlings if left unchecked. A good and cheap remedy against cutworm is fresh ash, which should be sprinkled around seedlings. Some farmers apply mixtures made from plants like tobacco and garlic to repel insect pests.
Calliandra seedlings are ready for transplanting 3 – 4 months after sowing. Depending on the weather, 2 weeks before planting you should reduce watering to once every 2 – 3 days. By this time you should have completely removed the shading materials covering the nursery bed to prepare the seedlings to withstand the field conditions when they are transplanted.
Prepare the planting holes in advance on an appropriate site before removing the seedlings from the nursery. If manure is available, apply a 1kg tin of manure to every hole and mix well with the soil.
Remove the seedlings carefully from the nursery bed after watering the bed thoroughly. The best method involves using a sharp panga to first cut between the rows, then between the seedlings to form squares, and lastly under the seedlings so that you can lift the seedling with a cube of soil attached to the roots. This improves survival in the field.
Place a number of seedlings in a container such as a bucket or basin for safe and convenient transportation to the field. Cover the seedlings with moist cloth or paper and take them to the planting site immediately. Prepare only as many seedlings as you can plant in one hour.