Manuring .—It is commonly said that coffee is an unusually exhaustive crop; but the exhaustion of the soil conaequent upon coffee culture is a result of the peculiar conditions under which it is prosecuted, rather than of the nature of the plant itself. Better than any amount of artificial manuring, is the retention of the naturally rich surface soil, by the effective prevention of wash. As a secondary adjunct, however, judicious manuring will be highl beneficial, and even necessary in almost all cases after the first year or two. It is impossible to lay down any hard and fast rule for manuring ; the most that can be done is to indicate the essential elements of coffee soils, the best artificial substitutes, and the best method of applying these substitutes. The best coffee soils appear to contain about 15 per cent. of combined iron, and alumina : the iron, if as red oxide, may amount to 20 or even 30 per cent., being a good absorbent of fertilizing constituents ; but the alumina should not exceed 10 per cent. Lime is an essential, which must be supplied if wanting ; this is too often overlooked, in the anxiety to furnish stimulants. The percentage of organic matter may be too high ; it should represent about 0.2 to 0.3 per cent. of nitrogen. The best average manure for supplying nitrogen and potash is well-rotted dung ; but its frequent application should be accompanied by a little lime, unless the soil is already very rich in that constituent; without the presence of lime, the shrubs will not receive the full benefit of the nitrogenous principles, but its use in a tropical climate must be governed by caution. Thoroughly fermented coffee pulp is a useful manure ; but it is only half as valuable as dung, and costs more to apply. It should be kept covered as it is produced, and is best mixed with fermenting dung, failing which, it should be well limed. Alone, it is of small benefit ; but forms a good vehicle for concentrated fertilizers. Almost all soils require a constant renewal of phosphoric acid and lime, which are not supplied by dung alone. These constituents are best furnished in the form of hones (steamed and ground), or concentrated superphosphate (containing 40-45 per cent. soluble phosphate of lime). Nitrogenous manures alone are too stimulating, and help to produce premature exhaustion, therefore bones may with great advantage be added to dung. Composts of pulp and cake are useful nitrogenous manures ; but they must be accompanied by phosphates and lime. Potash seldom requires to be directly applied ; but is advantageous after attacka of leaf disease. Magnesia seems to be a necessary oonstituent (from 0.5 to 2.0 per cent.) of all good coffee soils ; when wanting, dolomite may be applied. The great object of manuring is to supply all the constituents required, and in an available form. For coffee, the nitrogen is better applied in an insoluble form (as in dung, fish-manure, or cake), than in a soluble form (as in guano, sulphate of ammonia, or nitrate of soda). Phosphates are best conveyed in bones, when a lasting effect is required ; but high class superphosphates are preferable for immediate effect, as in cases of leaf disease. In tiopical climates, all manures a r best applied frequently and in small quantities. Regular manuring after each crop would doubtless be most generally economical and advantageous. The quantity must depend on local conditions, but should always be extra liberal after a full harvest. Artificial manures should be put out only in damp weather ; dung may be applied at any time. The lime must never be in a caustic state ; its best forms are gas lime and gypsum.
The manner of applying manures is not the same in all cases. No manure should be put more than 1 ft. below the surface of the ground, nor less than 18 in. from the stem of the coffee bush. On flat land, where there is no danger of wash, the manure may be spread over the surface, and heed in to a depth of 9-12 in., or a square hole may be cut between each four shrubs, and the manure buried in it. On slopes, it is usual to dig a hole alaove each bush. For bulky manures, it may be 2 ft. long, ft. wide, and 1 ft. deep ; for concentrated manures, its dimensions will be reduced. The holes should be filled up with any prunings or other vegetable matter at hand, and covered down firmly with the loose top soil ; the new earth from the hole should be spread around the stem of the neighbouring tree to protect its roots.
Ordinary manuring is sometime,s supplemented by other methods of improving the soil. One of these is to loosen it, by driving a long bar or a manure fork deeply into the ground, and then prizing up the earth, without turning it over. A second operation is that known as " mulching," or " ground thatching," which consists in oovering the ground under the bushes with a layer, 6-9 in. thick, of hard long grass. The deed of this in cold, wet soils, is to keep the ground warm, and to throw off excessive moisture ; io hot, dry situations, it is equally useful to retain moisture. In any case, weeds are kept down, and wash is quite prevented. When rotten, the grass may be hoed
or dug in.as manure. This thatching has been found a perfect cure for black bug. A third operation is called " trenching," or " waterholing." The trenches are made across the slope, and may be either open or closed. In the former case, holes, 3-4 ft. long, 12-15 in. broad, and 15-18 in. deep, are cut between each four trees ; the soil taken from them is spread over the roots of the trees, while the holes are left open to act as catch-drains, aud as receptacles for wash, weeds, pruning', and other vegetable matters, being emptied twice a year, and their contents spread amund the roots of the shrubs. Closed trenches are ditches cut across the entire length of the coffee rows, 2 ft. wide and deep, and filled with any vegetable rubbish at hand ; they are then covered with earth, and well trodden down, while the remaining soil is spread under the trees. The benefit of trenching is greatest in stiff soils. The refuse matter in the trenches should be limed, to kill grubs and other vermin for which it will form a nursery.
Diseases and enemies.—Besides peculiar conditions of climate, aspect, drainage, shade, shelter, &c., already alluded to, particular attention must be paid to the prevention or cure of certain maladie,s to which the coffee shrub is specially liable. The number of these iusectiform and fungoid pests is considerable ; but the only ones of sufficient importance to merit description are leaf-blight, fly, borer, bug, and canker.
1. Leaf-blight.—The leaf-blight of Ceylon and Southern India was first noticed in the former country about 1869, and in India two years later ; by 1875, it had devastated whole districts, and since then it has been found in Sumatra and Java. Its existence at a distance from the Indian Ocean has not yet been proved, though there is some suspicion that an allied disease is indigenous to Western Africa. It is a fungus, known as Hemileia Vastatrix, and allied to the moulds. It is present in some form or other all the year round, and first attacks the under side of the leaves, causing spots or blotches, at first yellow, but subsequently turning black. These blotches are covered with a pale orange-coloured dust or powder, which easily rubs off ; they gradually increase in size, until at last they have spread over the leaves, which then drop off, leaving the trees unable to produce crop, or to bring to maturity that which may have already been produced.
In districts affected by the south-west monsoon, during December to February, the fungus generally exists as an external parasite, in the form of long filamentous threads, covering every part of the bark and leaves, but so minute as to be invisible to the naked eye. The disease was made the subject of an official inquiry, by Daniel Morris, of the Peradineya Botanic Gardens, from whose report it appears that a successful mode of treatment has been found. Of the many materials experimented with, one only is invariably effective, viz. a mixture of best quality flowers of sulphur with caustic lime, in the proportions of 1 part (by weight or measure) of the former with three parts of the latter-1 : 2 gives much better results at increased cost—and thoroughly incorpo rating them before use. When small areas only are to be treated, sulphur blowers may be used for applying the powder ; but it can be as effectively spread by hand, taking care that it is thrown upwards into the tree, and that the stem and branches become well coated. Sufficient will generally fall to the ground to disinfect the vegetable matter lying there ; but under large and leafy bushes, a few extra handfuls may be sprinkled. This will especially apply when " mulching," or opeu trenching, is carried on. When once the mycelium, or vegetative part of the fungus, has penetrated the tissues of the leaves, no remedy can be used which will not also destroy the leaf. The only opportunity for combating the disease is while it is in the invisible- filamentous state, on the exterior of the bark and leaves. At this time (December to February), each tree should be treated with about 5 oz. of the mixture, not omitting to disinfect the ground and whatever encumbers it. It has been observed that the treatrnent produces marked beneficial effects upon the trees in other ways ; their appearance becomes more vigorous and healthy, the foliage improves in texture and colour, the wood matin.es and bears earlier, the blossom sets better, and the crop is heavier. The measure is preventive only. The disease being infectious, and the spores of the fungus easily distributed by wind, every precaution should he taken to eradicate it fi.om aban doned coffee patches, and stray wild trees. Such had better be burnt, and the ground occupied by other produce. The cost per acre of the treatment is estimated as follows :—Flowers of sulphur, 1 cwt., R. 10 ; coral lime, 3 cwt., R. 5.25 ; band spreading, R. 1 .25 ; total, R. 16.50. In hardly any case would it exceed R. 18-20 an acre, without transport.