I have pointed out that phosphoric acid is retained by the soil, and it is important to remember that it is only removed by the crops of coffee to the extent of from one-and-a-half to two pounds per acre per annum, and these are two facts that every planter should bear in mind when he contemplates following the common custom of manuring with bones. For if he remembers that about one-half of the bones consists of phosphate of lime, and that about one-half of the latter consists of phosphoric acid, he will at a glance see, when he estimates the amount of phosphoric acid removed by the crops, that if he puts down even 100 lbs. of bones per acre he will have put down enough phosphoric acid for about twelve crops of coffee. And yet for a planter to put down 3 cwt. of bones per annum regularly is quite a common thing, and a friend of mine, after having manured his land one year with bones to a moderate amount, put down each year, for the two following years, no less than three-quarters of a ton of bone-meal per acre. So that, making a large allowance for the phosphoric acid taken up by the shade trees, he had put down, in these last two years, enough phosphoric acid to last for the crops of 300 years. From the application of bones he had undoubtedly obtained a great benefit, but I feel sure that it was from the lime and the nitrogen of the bones, for the application of bones that preceded the two applications of three-quarters of a ton per annum must have left the soil amply supplied with phosphoric acid. Now assuming that the soil required lime, and a moderate degree of nitrogen, these could have been supplied far more cheaply, and just as efficiently had my friend applied a small dressing of ordinary lime, and some oil-cake, and I am the more convinced of the accuracy of this view after visiting Mr. Reilly's Hillgrove estate near Coonoor on the slopes of the Nilgiri hills, and hearing the result of his very long experience. Bones he had never used but once, and that on a small portion of the estate, but he had always applied lime once every three years at the rate of about 4 or 5 cwt. per acre; the other manures he had used were cattle manure, and town manure from Coonoor, and these added to the small quantity originally in the soil, had supplied his coffee amply with the 2 lbs. of phosphoric acid annually removed by the crops. After much consideration, and hearing Mr. Reilly's views, it seems quite clear to me that as but a small quantity of phosphoric acid is removed by the crops, and as that manure is firmly retained by the soil, bones need only be used at long intervals provided lime is regularly applied in small quantities.
And next, before we can approach, or attempt to determine, the quantity of manure required, we have to take into account the loss by wash, either from the surface or by downward percolation, and the absorption of manure by the roots of the shade trees. We have also to take into consideration the manure returned by the shade trees in the shape of fallen leaves, and the ammonia derived from the rainfall, so that it is impossible to state with any approach to accuracy the amount of manure that should be applied. We can only say then that, whatever the required amount may be it must be very considerable, for in addition to the above-mentioned losses of manure, we require a considerable amount for the demands of the coffee trees, and that, further, it must vary with the amount of the rainfall, and the retentive or non-retentive character of the soil. The crop, it is true, takes comparatively little from the soil, and Mr. John Hughes, Agricultural Chemist, 79, Mark Lane,—points out in his "Reports on Ceylon Soils and Coffee Manures," that 5 cwt. of parchment coffee an acre, which is an average crop over a long series of years, only removes from the soil—
| lbs. | |
|---|---|
| Nitrogen | 8¼ |
| Potash | 7½ |
| Phosphoric acid | 1½ |
| Lime | 1 |
| Total | 18¼ |
Assuming then, he tells us, that the small quantity of potash required could be supplied by the soil, and that the pulp is returned to it, the loss by the crops could be fully supplied by 100 lbs. of castor cake and 10 lbs. of bones per acre. Then if we require much more from the plant than the production of crop (for we expect it, in addition, to grow wood for the succeeding crop, and during this process the plant grows much superfluous wood, besides suckers, which have to be removed), it must be remembered that all primings and superfluous wood are left on the land. What there is actually carried off it is really very small in quantity. Why, then, it will naturally be asked, is it necessary that so much manure should be present in the soil if we wish to grow good coffee and have continuously good crops, and why is it that if manuring is neglected you will soon find that it is only the rich hollows that are able to maintain the coffee in good condition and produce good crops continuously? To such questions no distinct answer can be given, and we can only conjecture that coffee, when it wants its food, must, for some unknown reason, have a considerable supply at hand. There is, however, one test which, I think, always shows conclusively whether this food is present in the quantity required to supply the needs of the plant. Just before the hot weather the coffee trees throw out a small flush of young wood. Now if the trees have given a fair average crop, and at the same time have a good show of bearing wood for the next season's crop, and are also throwing out a good supply of vigorous young shoots, then you may be sure that your land is well fed. But if the trees throw out no young shoots at that time, or very few, then you will know that your land is not as well fed as it ought to be.
It might naturally be supposed that I could furnish some guide to the planter, from our experience in Mysore, as to the quantity of manure that should be put down, but I regret to say that I am unable to do so, as I know of no estate where a regular and continuous system of manuring has been carried out. But in North Coorg, and very close to the Mysore Border, the continuous practice on Mr. Mangles's Coovercolley Estate of 500 acres gives a fairly approximate idea of what can keep an estate in a well-fed condition. There the practice has been to put down every third year from 7 to 10 cwt. of bone-meal an acre, and one-third of a bushel of cattle manure, and, besides this, composts of pulp, mixed with top soil and lime. Now this is the finest estate I ever saw. The coffee was even and of a beautiful colour, and when I saw it towards the end of 1891 there was a fair crop of coffee on the trees, and an ample supply of young wood for the following crop, and the land was so well fed with nitrogen that an experimental application of nitrate of soda to a part of the land had produced no perceptible effect on the trees. From what I have previously said as to the application of bone-meal being overdone, I think it probable that the estate would have presented as good an appearance had the land, after once being well stored with phosphoric acid, been treated with small applications of lime instead of bones. Then another estate I saw in 1891 in Coorg, in the Bamboo district, furnished some guide as to the amount of manure required where cattle manure was not available, and on the estate in question, which had both a good crop on the trees and ample wood for the future, I was informed that, in the year previous, 6 cwt. of castor cake and 3 cwt. of bones had been applied per acre, and that for the four preceding years 4⅓ cwt. of manure, containing 2 parts of castor to I of bones, had been applied, but that the last-named amount had been found to be too small. The reader will find in the chapter on Coorg some further information, which has since been supplied to me by Mr. Meynell, on this point.
The quantity of manure that should be put down at a time is evidently a matter of great importance, as if you begin by putting down a large application you are certain to have an over-heavy crop, followed by exhaustion, and a very poor crop the following year, while the object of all intelligent fruit cultivators is to work for moderate even crops. It seems quite clear, then, that we should manure little and often, as you thereby not only avoid the risk of over-heavy crops, but economize your manure. For is it not obvious that if you put down at once a supply of nitrogen and lime to last for three years, you increase the risk of loss from wash and downward percolation? And it must also be considered that an over-heavy crop leaves the trees in an exhausted and dried-up state to go through the hot weather, when they will be liable to be attacked by the Borer insect, which, as we shall afterwards more particularly see, delights in dry wood. So that when we further take into consideration the injury to the constitution of the trees which is caused by over-heavy crops, we need have no doubt that there is much reason to dread them. I would therefore strongly deprecate, for the preceding reasons, heavy manuring (even the mind may be over-manured in the eager desire to arrive at a cultured intellect), and would advise that a beginning be made with a moderate application, and, if this is found to be insufficient, that the amount be gradually increased till the trees show that they can with case give regular average crops. If cattle manure or jungle top soil is available, a quarter of a bushel a tree may be annually applied of either, accompanied by 3 cwt. of bone-meal. And, if neither of the two former sources are available, then 3 cwt. of bone-meal and 2 cwt. of white castor cakes would be a reasonable application. After applying 3 cwt. of bone-meal per acre for three consecutive years the land ought to be amply stocked with phosphoric acid, and the bone-meal should be discontinued, and its place supplied with small applications of lime, either annually or at intervals of two or three years, should the latter course be more convenient. And subsequently, when there is reason to suppose that the land requires a fresh supply of phosphoric acid, an application of bone-meal may again be used. I would particularly warn the planter against over-manuring light dry soil, or south and south-western aspects, or the upper and drier portions of eastern aspects, as an over-heavy crop on these aspects is very perilous even with good shade, for we may not have a drop of rain from November till April, and should such a drought occur, and be preceded by a dry season (and such seasons occurred in 1865 and 1866, and caused the great attack of the Borer insect, which was so fatal to all insufficiently-shaded coffee, and from which even well-shaded coffee suffered to some extent), or should even a single dry, hot season follow immediately after the crop is picked, there would be sure to be a serious drying up of the plant, with but small chance of its bearing anything worth having the season following, and very great risk of a severe attack of Borer. But on northern and north-western aspects the land is not exposed to parching east winds, and, as we have seen, has a temperature about one-half cooler than that on a southern aspect, and the planter may therefore on such aspects manure with greater freedom. But even in these aspects I am sure that over-heavy manuring will lead ultimately to injury to the trees, and, in a series of years, to the production of a smaller amount of coffee.
I have indicated the amount of manure which in my opinion ought to be put down when manure is applied for the first time on a plantation, and if the plantation is of a flat character, or only on very moderate slopes, the manure should be evenly applied all over it. But if, as often happens, there are hollows and ridges on the land, then the ridges should be, as a rule, much more heavily manured than the hollows, for which a very little manure will suffice, as so much is washed into them, and they are, besides, much richer to start with. It is very important to note at the outset all those spots which, in the original forest, are very rich, so that the manure may be applied accordingly, and though, as I have said, the ridges as a rule are poor, there are many instances where the top of a ridge, from being pretty wide, is rich, though the sides of it for a little way down are nearly always poor. I have lately been minutely examining old forest land, with the view of removing top soil from it, and have been much struck with the variation in the depth of the rich surface soil.
We have next to consider the time of year at which manure should be applied to the land, and here we shall find that the planter, like the farmer, often has to do things when he can, and not when he should, and though, from the risk of loss by wash alone, there can be no doubt that all manures should be put down after the heavy rains of the monsoon are over, it is difficult to see how this can be carried out in the case of bulk manures, on account of the difficulty of getting enough labour to at once cope with the ordinary estate work, and apply a class of manure which absorbs so much hand labour. Then there is the difficulty of carting manure at that season when the roads, which are not macadamized, would be cut to pieces. But this difficulty could be overcome were a sufficient number of storage sheds provided to which the manure might be carted during the dry season. But the sheds would cost a good deal of money, and the cost of the manure would be increased by the cost of extra handling, or in other words putting the manure in the sheds and taking it out again. So that I am inclined to think that it would be better to apply, by direct cartage from the cattle sheds, as much bulk manure as can be applied in the month of September, and the remainder at any convenient time after crop. Another great objection to applying manure after crop, and before the monsoon, is, that you stimulate the growth of the weeds which spring up with the early rains, and also much growth of suckers, and superfluous wood in the coffee, all of which have to be handled off at considerable expense, whereas, it is hardly necessary to say, that the weed growth is smaller at the end of the monsoon, and the force of the plant directed rather to the maturing of the berry than the growth of surplus wood. But in the case of light manures such as bones and castor cake, there is no difficulty in applying them in September, and an effort should certainly be made to put them down then. Another advantage of manuring at the end of the monsoon would be that the planter could then clearly perceive what trees would be certain to give a good crop, and give them an extra quantity of manure, and also diminish his application of manure in the case of such parts of the plantation as might be yielding a small crop. I may here mention that, from reliable information received from Coorg, results there have shown that it is best to apply a portion of the manure after crop to strengthen the blossom, and a portion after the heavy monsoon rains are over to strengthen the trees and assist in maturing the crop.
But the most important point, perhaps, as regards the best time for manuring is the bearing that the time of manurial application has on leaf disease, and Mr. Marshall Ward in his third report on leaf disease (p. 15) has some most valuable remarks on this question. "The object of the planter should be," he says "to produce mature leaves as soon as possible and keep them on the branches as long as possible." Now if leaves are produced in April and May they become attacked by the fungus while still young, and in August and September the ripening crop is left bare on the branches. But the leaves which were in bud in December are matured and well hardened, and have already, by living longer, done much service to the tree. He then points out that when certain districts in Ceylon suffered from a bad attack of leaf disease in July, "a large surface of young and succulent leaves were ready to receive the spores of the Hemeleïa." The germination of the spores was rapid, and the young leaves were soon destroyed. The planter then, he says, should manure and prune so as to grow matured leaves during those months when the least damp and wind may be expected. And the same remarks are evidently equally valuable as regards rot, and show us the necessity of modifying our manurial and pruning practices so as to enable the tree the better to contend against it as well as leaf disease. All manuring, then, which leads to the production of young succulent foliage just at the beginning of the rains should be avoided, and the same remark applies equally to pruning. But I shall again return to the subject when writing on pruning.
As to the best method of applying the manure, great differences of opinion and practice exist. At one time in Mysore it was customary to cut a shallow trench in the shape of a half moon around the upper sides of the trees about two feet from the stem, and deep enough to contain the manure, which was then covered in with the soil taken out. But this process was found to be expensive, and of course took much labour, which is sometimes extremely scarce, and on my property we have for some years past—excepting in the case of manuring with fish, which is liable to be carried off by birds, dogs, jackals, and village pigs—scattered all the manure on the surface, and close around the stem of the tree, with the idea that the manure would be less likely to be taken up by weeds, and by the roots of the shade trees. But in connection with this system there is a fact which I did not take into account, but which is well worthy of careful consideration, and that is, that the tendency of such a system of manuring is to keep the coffee roots close to the surface. Now it has been suggested by the late Mr. Pringle, whose opinion on another matter I have previously given, that this would have an unfavourable effect, if we had, as sometimes happens, deficient blossom showers; as in that case, and with many rootlets near the surface, a stimulus would be given to the plant which would induce it to throw out the blossom when there was not enough rain to bring it to perfection; whereas, if, by putting down the manure more deeply we attracted the roots downwards, the blossom buds could only be started after such an amount of rain as would give the soil such a soaking that a successful blossom would be insured. There certainly seems to me to be a great deal in this idea, but I am not aware that we have had any experiments made side by side as regards surface manuring, and manuring in pits, and therefore am not in a position to express a decided opinion on the subject, but theoretically there would seem to be much in favour of burying manure in pits, and it seems certain that the manure would be less likely to be taken up by weeds than in the case of surface manuring.