Culture.
Propagation.—The place selected for seedbed and nursery should be well drained, with a loamy soil, the richer in humus the better. A light bamboo frame should be erected above the nursery plot about 2.5 meters high, and covered with grass or split bamboo to provide about half shade. The land should be spaded thoroughly to a depth of 30 centimeters, and all stones, roots, etc., removed. One meter is a convenient width for seed and plant beds.
The seeds should be sown broadcast, not too thick, covered with not more than 1 centimeter of earth, and then watered thoroughly. Hereafter the seedbed should be well watered from time to time whenever the soil appears dry. Frequent light sprinklings that do not allow the water to penetrate more than a few millimeters below the surface are harmful rather than beneficial both in the seedbed and the nursery, in that they encourage a shallow root formation.
As soon as the first leaves are fully expanded the seedlings should be transplanted to the nursery beds, which should be prepared like the seedbed. If the land is poor it is well to spade in a liberal quantity of well-decayed manure or compost. The plants should be taken up carefully, the taproot nipped off with the thumb nail, and then transplanted with the aid of a pointed stick or small dibber spacing them 10 to 15 centimeters apart each way. In doing this care should be taken that the roots are not doubled up in the hole and that the soil is well packed around them. More plants should never be removed at one time from the seedbed than can be conveniently transplanted before they show signs of wilting, and the dug plants should not be left exposed until the roots dry out. The plants should be thoroughly watered before and after transplanting, and the beds kept free from weeds and watered as often as necessary.
Clearing and planting.—Wherever possible, the land to be planted in coffee should be stumped, and plowed once or twice, so that after the plants have been set out animal-drawn cultivators can be used to keep down the weeds. Thus the cost of weeding is lessened during the early years of the plantation while the plants are small. If plowing is not feasible holes 1 meter in diameter and at least 30 centimeters deep should be grubbed where the plants are to be set.
On moderately rich land robusta coffee should be planted 2.1 meters apart each way, 2,265 plants to the hectare; on very fertile land the distance may be increased to 2.5 meters, or 1,600 plants to the hectare.
Arabian coffee should be spaced from 2 to 2.5 meters apart or on poor lands even closer.
When the plants are 4 to 5 months old they should be about 20 centimeters tall and ready for transplanting. About one-half of the foliage should now be cut off; a trench should be dug at the end of the nursery bed about 20 centimeters or more deep; then a thin, sharp spade or bolo (cutlass) should be passed through the soil, underneath and around the plant, neatly severing all straggling roots, and leaving the plant in the center of a ball of earth. The plants should be set out in the field at the same depth at which they grew in the nursery, great care being taken not to break the ball. If the soil is so loose that it falls away from the roots in the removal from the nursery, great care should be exercised in not allowing the roots to dry out and in setting out the plant so that the roots fall in a natural position. In the course of the planting the soil should be firmly packed about the roots.
The sowing of the seed in a given locality should be so timed that the plants are ready for transplanting at the beginning of the rainy season in order to avoid the expense of artificial watering. If transplanted during the dry season the plants necessarily would have to be watered by hand from time to time until they are established.
Plants for shade.—As a temporary shade and cover crop of rapid growth while the coffee trees are small, perhaps no plant can compete with the cadios (Cajanus indicus). The plants may be cut down to serve as mulch whenever they grow too high, and may be expected to grow from the stubble twice before the plants die, provided they are not cut off too close to the ground.
In Java, where robusta coffee is more extensively planted than anywhere else, permanent shade is considered advisable. Malaganit (Leucaena glauca), a leguminous shrub which grows everywhere in the Philippines, seems to be preferred there to other plants for shade. It is planted alternately with the coffee plants and, as is the case with all plants utilized for shade, thinned out later according to need. Madre de cacao (Gliricidia maculata) and dapdap (Erythrina indica and E. subumbrans) are other leguminous trees readily obtainable in most localities and are adapted for shade.
Madre de cacao should be planted at the same distance as the malaganit while the dapdap should be planted one plant to every two coffee trees. All these plants are readily propagated by cutting off limbs or branches 1 to 1.2 meters long and inserting them 20 to 30 centimeters deep in the ground during the rainy season. (This is most conveniently done by the aid of a crowbar.) In a limited way fruit trees, such as the soursop, custardapple, breadfruit, and jak may also be used as shade, and these should be planted from 6 to 12 meters apart according to size. The necessary shading between these trees while they are small may be provided by planting malaganit, etc.
Robusta coffee has also been successfully interplanted with coconuts. In this case the palms and coffee should of course be planted at the same time, the palms perhaps not closer than 9 to 10 meters apart, the coffee to be used as a “filler” between the coconuts. In this connection it is perhaps well to state that in Java robusta coffee is very frequently planted as a “catch crop” in the Hevea rubber plantations. Among the shade plants available to the Philippine planter, malaganit, dapdap, and “guango,” or raintree (Pithecolobium saman), have given the best results in Java for the robusta with the following ratio yield of coffee: 4.75, 4.10, and 3.06.
Cultivation.—On level and well-cleared land, close attention should be paid to keeping the coffee plantation free from weeds during the first year or two by means of animal-drawn shallow cultivators, supplemented with hand-hoeing. Where the topography of the land or the presence of stumps renders this impossible the weeding must of course be done by hand. All weeds should be left in the field where they serve both as a mulch in preserving the moisture and to enrich the soil. As soon as the plants begin to shade the land they thereby aid in the weed eradication, and weeding then becomes less expensive.
Pruning.—If the trees are allowed to grow without pruning they become too tall (robusta coffee attains a height of 6 meters or more), and the topmost berries are then difficult to pick. Furthermore unpruned coffee trees (including robusta), have the peculiar habit of bearing their branches near the ground and at the top, leaving the middle bare or nearly so which decreases the producing capacity of the plant. On this account up-to-date planters have generally adopted a system of pruning by which the coffee trees are headed low, giving a maximum yield coupled with easy access to the berries.
The pruning consists of topping the robusta trees when they are from 2 to 2.5 meters tall and of subsequent pruning to keep the trees at this height. This work should preferably be done while the plants are of the proper height and the green shoots easily broken off, and not after the trees have exceeded the height limit by several decimeters. The plant, if allowed to do so, usually sends up a large number of suckers from the base, which constitute a drain on the vitality of the plant. Therefore, all superfluous suckers should be removed and not more than 2 to 3 stems to a plant should be permitted to develop.
Occasionally robusta plants appear that are more than ordinarily subject to blight, and these should be at once pulled up and burned.
Yield.—The yield of robusta coffee is quite variable, much depending upon the fertility of the soil. On the more fertile soils in Java the yield per hectare in the third year was approximately 540 kilograms, and in the fourth and fifth years, 1,400 and 1,830 kilograms, respectively. In old coffee or cacao fields the yields were 325, 540 and 850 kilograms per hectare, respectively, during the third, fourth, and fifth years after planting. It is perhaps well to recall the fact that the average yield of Arabian coffee in the Philippines is 174 kilograms per hectare, which is of course much less than it should be, and it is not believed that the Philippine planter with his present methods of cultivation could equal with robusta coffee the yields quoted from Java.
The immense superiority of the robusta as a cropper over the ordinary Arabian coffee is best illustrated in a table published by the Department of Agriculture, Java. We learn here that in Java, under identical conditions, the yield per plant was of Arabian coffee, 53 to 97 grams; of robusta, 992 grams; and of quilloi (a new very rare coffee) 1,020 grams. The Maragogipe hybrid on its own roots yielded 14 to 18 grams, while grafted on robusta the yield was 156 grams, a larger crop than any Arabian coffee has given in Java. This would tend to show the possibilities of robusta as a stock. Further, comparative studies by Cramer have shown that 4 to 5 kilograms of fresh robusta berries make 1 kilogram of coffee while of the Arabian coffee 5 to 6 kilograms of fruit are required to make 1 kilogram of coffee.
Owing to the fact that the pulp on the robusta coffee (though smaller in amount) is more difficult to remove than that on the Arabian, robusta needs at least two and one-half days of fermentation. The bean requires rapid drying in order to loosen the silver skin and the drying is therefore done in an artificially heated shed.
Quality and marketability.—Relative to the quality of the robusta coffee Doctor Hall says:
The appearance of the average marketable robusta is not very beautiful; the beans are small and irregular, and the average product shows little uniformity. There are, however, great differences between the many different types of robusta. Some of them have comparatively large beans, larger even than arabica, others again have very small ones. As regards the quality, though being inferior to Java-arabica, the taste is generally considered to be good and superior to the ordinary arabica sorts, as Santos.
Doctor Wildeman states:
It is objected that the berries of the robusta group and of other African coffees are small in size and inferior in flavor; but the continually increasing quantities of these coffees sold in Holland, and the satisfactory prices they fetch show that the public is beginning to appreciate them. No objections will be made to the size of the berries when by means of careful cultivation and especially of right preparation, a coffee is obtained equal in flavor to the (old) Java and Arabian coffee.