Several species of shrub of the genus Coffea produce the berries from which coffee is extracted. The two main species commercially cultivated are Coffea canephora (predominantly a form known as 'robusta' and C. arabica. Arabica, the original and most highly regarded species, is native to the southwestern highlands of Ethiopia and the Boma Plateau in southeastern Sudan and possibly Mount Marsabit in northern Kenya. Canephora is native to western and central subsaharan Africa, from Guinea to the Uganda and southern Sudan. The robusta strain arrived in Java around 1900. In Java both species are commonly used over the years. At the plantation Blawan and Kalisat Arabica is grown.
Coffee fields at Ijen Plateau
At Ijen Plateau you find many different fields: those who seem to be empty, those fully occupied with coffee and those with not only coffee but also orange trees, macadamia nuts and trees for shade.
The fields that seem to be empty sometimes are indeed empty. Those fields are waiting for the seedlings grown in the green houses to be ready. They are planted in the fields, after they reached an age of one year. Sometimes these fields aren't empty. Old coffee trees are cut about 50 centimeters above the soil. This is also called the Ijen Pruning System. The plants are cut because production dropped, but the root system is still very strong. These tplants will sprout again and come back into production. At the Ijen Plateau the coffee plantations are diversifying, in particular in Kalisat. Nowadays, oranges and macadamia nuts are intercropped with coffee. Besides, the trees for shading the coffee (prosia) will eventually be used as fire wood. Otherwise, strawberries are a new product.
Greenhouses and modern experiments
Coffee is sown in greenhouses in Blawan. The seedlings grow under full coverage of plastic until they are three months old. Then they grow till an age of 1 year in the open air. If they reached that age, they are planted in the fileds at the Ijen Plateau. Because of problems with the roots of the arabica coffee plants, a grafting experiment - based on results of the coffee plantation in Jember - has started this year. Robusta forms the stem, while arabica is on top.
Large differences in productivity
Of the more than 60 existing species, only the Coffea arabica and Coffea canephora are commercialized. From each species there are several varieties with different flavours, but also large differences in terms of productivity, which can range from 3 to 12 tonnes per hectare. While arabica can fertilize itself, the robusta need two trees for reproduction. The quality of the coffee depends on several factors: botanical species and variety, terrain, temperature, altitude, sun exposure, amount of light (shade), water (irrigation) and wind.
Flower of coffee: 'Arabian jasmine'
A coffee plant bears flowers after three years. After another two years, the first coffee can be harvested. In Kalisat it depends on the production per hectare whether the management decides the trees are fully grown and the beans are ready to get harvested. If the harvest per hectare is nog high enough, the beans are picked but not processed. The flower of the coffee plant looks like a jasmine flower. Therefore, the tree beared the name 'Arabian jasmine' until the 17th century. The flower brings a stone fruit which needs 6 to 9 months to mature. Normally coffee blossoms twice a year. But under the influence of humidity, the coffee plant can blossom up to 8 times a year. This explains why in one twig different stages of maturity may reside. The ripe fruit is red, shiny and firm. Immature fruits give the coffee a sharp flavour, too ripe coffee tastes bitter and unpleasant.
Top production in June and July
There are four methods to pick coffee. They differ by their accuracy and cost price. 1. Stripping: the branch is ripped of all fruits - both ripe and unripe - and flowers 2. Combing: with a special comb, with smooth and spaced teeth, are 'combed' of the branch. The ripe red berries fall off, while the green berries linger 3. Mechanical: tractors with combs remove the berries, but also the flowers and the leaves. This method is in Brazil widely used and is effective. But the quality is low as is the case with stripping 4. Picking: only the ripe berries are hand-picked.
At the plantations at the Ijen Plateau method 4, hand picking, is used. Labour in Java is still very cheap. Besides, many companies prefer to offer more people a job instead of only a few in combination with mechanization. Most coffee is picked in the months June and July, in August the daily harvest already declines.
The trees at the Ijen Plateau can easily reach an age of 40. But, depending on its age, the production per hectare declines. Besides, years in which a coffee plant bears many beans are alternated by those with less beans. On average the production at Ijen Plateau is between 600 and 1000 kg per hectare. The harvest depends besides age of the plants also on location - mainly height - and climate.
Fungi threaten arabica
The diseases that coffee affect are usually caused by fungi such as hamelia vastatrix. They arose in the 19th century and destroyed thousands of hectares of arabica plantations in India and Indonesia. Nowadays, there is a simple treatment. Another potential threat is the bark beetle, which go for the beans. After they are done they leave the berries behind full of holes. Robusta is less susceptible to disease than arabica and can be cultivated in lower altitudes and warmer climates.