tilizer, does not lose it, but is able to reap the benefits from it in the next year's crop. If it were not for this power, the best method for applying fertilizers would be a much more complicated problem than it is at present, as it would be necessary to apply them at just the proper season, and in nicely regulated amounts to insure against loss."

PINEAPPLE SOILS LACKING IN ABSORPTIVE POWER.

Of course Huston and Goss did not have in mind such soils as the East Coast pineapple soils when they wrote this, for we have there just the conditions which they say would make the problem of fertilizer application much more complicated than it is, and make it necessary to apply the fertilizers at just the proper season and in nicely regulated amounts to insure against loss.

We have there a soil which is practically devoid of clay and therefore of zeolitic materials; which contains only traces of iron, lime and magnesia, and a comparatively small amount of organic matter, but which is on the other hand, 98 to 99.5 per cent. insoluble matter-much of it being very coarse sand-hence there are wanting nearly all those properties which in ordinary soils would effect the absorption of soluble plant food. As a consequence the amount actually available for the plants probably cannot much exceed that which they make use of soon after the application is made, or before the falling of a heavy rain, and that which is mechanically held, and this last is undoubtedly small where the sand is so coarse, and where there is so little organic matter.

Even organic fertilizers such as bone meal, cottonseed meal, dried blood and castor pomace, are slowly converted into soluble forms in the soil, and on account of the almost entire absence of those substances which produce absorption phenomena (a binding of soluble plant food) a large part of this soluble plant food, if not seized upon at once by the plant roots, probably goes down with the first rain.

VALUE OF SLOWLY AVAILABLE MATERIALS FOR SUCH

SOILS.

Nevertheless there is under such circumstances an advantage in using slowly available forms over the readily soluble forms, for while they are thus being made available, the plants are being benefited, and the excess to be carried away by percolation is not so great.

I believe one of the merits of slag phosphate, for use on sandy soils, lies in its somewhat insoluble, but nevertheless slowly available form of phosphoric acid. When applied from year to year, a small amount is being rendered available all the time, and at the same time no very great amount is lost by percolation. I further believe that if we could get a more slowly available form of potash for such soils, the problem of fertilizing pineapples would be simplified and the expense reduced. The good results obtained with tobacco stems might possibly be attributed to the fact that the potash becomes slowly available, and thus in the end is nearly all taken up by the plant.

PLANT FOOD AND CAPILLARY ACTION.

But some one asks, may not much of this lost plant food be recovered and brought within reach of the roots by the capillary action of the soil moisture?

If the soil were a clay or a clay loam the answer would certainly be in the affirmative, but in such coarse sandy soils the conditions are very different. It is a well known physical fact that when three tubes of different internal diameters are placed open end in water, the water will rise highest in the smallest tube, that is, the smaller the tube, the greater the capillary action. So with the soil, the finer the particles the greater the capillary action, and as the particles of sand composing the pineapple soils are very large in comparison with the particles that make up clay soil, so the amount of water, and hence of plant food, brought up from a deep soil by capillary action is correspondingly smaller. Hence it is that plant food when once lost in the waters of the sub-soil, are recovered but slowly and with great difficulty by capillary

action. This was well illustrated by another experiment conducted in our laboratory.

Over the end of a glass tube of about 3-4 inch internal diameter, was tied a piece of muslin cloth, and in the tube was placed the pineapple soil to a depth of 12 inches. The tube was then suspended so that the end over which the cloth was tied just touched the surface of distilled water contained in a beaker. At the end of three days the highest point at which the soil had been moistened by capillary water was 3 3-8 inches. The same experiment was tried with the Columbia county soil, and the South Carolina clay soil with the result that at the end of the three days the Columbia county soil was moistened to a height of 8 3-8 inches, and the South Carolina clay soil 10 7-8 inches. In each case the tube was weighed with the dry soil, and again at the expirIation of the three days. The pineapple soil retained 8.9 grams of water, the Columbia county soil 23.4 grams, and the South Carolina clay 27.2 grams or a little more than three times as much as the pineapple soil. This indicates very clearly the difference in capillary action. In the pineapple soils the grains are large and as a consequence many of the spaces between them are too large for capillary spaces.

To illustrate in another way, if you could put these grains of sand together into the form of a lamp wick, you would still have a very poor medium for lifting oil, but if the wick be made of fine particles of asbestos, which is also a mineral, the oil is raised without difficulty and a good flame is the result.

SOME REMEDIES SUGGESTED.

WITH ESPECIAL REFERENCE TO PINEAPPLE SOILS.

Then is it possible to do anything to prevent this great loss of plant food?

Certainly it is not possible and perhaps not desirable to convert the sandy soils into clay soils, nor even to mix with the sand a small percentage of clay.

I will mention a few ways that have suggested themselves

to me.

(1.) By increasing the amount of organic matter in the soil.

It is a well established fact that organic matter acts as a sponge to hold moisture, and in holding water it will hold plant food. This was well illustrated in the experiment with the muck soil. One hundred and fifty grams of an air dry muck soil retained over 100 grams of water, and 90.9 per cent, of the sulphate of ammonia. Whereas the same weight of the pineapple soil retained only 30 grams of water and 5.77 per cent. of the sulphate of ammonia. Old pineapple plants and other organic matter might be allowed to decay on the fields instead of being burnt. Other ways will doubtless suggest themselves to those interested. Of course the pineapple grower cannot resort to cover crops such as velvet beans, cowpeas, beggarweed etc., as can the man who grows oranges or ordinary field crops.

(2.) By the use of windbreaks.

Currents of dry hot air passing over the fields cause the surface moisture to evaporate rapidly, thus to a certain degree breaking the chain of capillary moisture.

(3.) By the addition of lime to the soil.

In some soils lime tends to produce a flocculent effect (a binding together of the minute particles into flakes) which condition makes the soil more retentive of moisture.

In a sandy soil the tendency would be for the lime, after it has been carried down a short distance, to begin to cement together the grains of sand and thus form a layer somewhat impervious to the downward movement of water, thus preventing to some extent, the loss by leaching. In using lime, however, care must be exercised that it be not used in such a way as to cause the loss of ammonia from other materials, sulphate of ammonia for example.

(4.) By using fertilizing materials which become slowly

available.

For such a crop as pineapples, where the plants remain in the ground from year to year, there would seem little reason

for using quickly available materials, except say for the first eighteen months, to get the plants started, even had we a soil that was capable of absorbing and holding the plant food.

After a certain amount of these slowly available materials, have been added to the land some plant food is being rendered available all the time, and as the roots are there ready to utilize it, not so much is lost by seepage to the soil waters below. It seems to me, too, that this same reasoning might apply to the fertilization of orange trees.

(5.) By shading.

Shading undoubtedly tends to conserve soil moisture, and if we can retain moisture near the surface, it means more moisture and with it more plant food brought up from the deep sub-soil by capillary action. This latter fact is demonstrated in the alkali regions of the west. As soon as they begin to irrigate land that is impregnated with alkali, the alkali commences to rise through capillary attraction from a subterranean source and in many instances completely destroys nearly all kinds of vegetation.

(6.) By smaller and more frequent applications of fertilizers.

In the light of the evidence before us, I am strongly inclined to the belief that it would be economy to fertilize pineapples from four to six, instead of two to three times a year. I am aware that this is not in accord with recommendations made in our recent bulletin on pineapple fertilizer experiments, but at the time those recommendations were made, .we had not discovered that such a large percentage of the plant food applied to pineapple soils, was unaccounted for.

If the farmer should give to his horse at one time, food enough to last it one week, he would expect much of it to be wasted; so if you give to your pineapple plants soluble food enough to last them six months, and there is nothing in the soil to bind or absorb this plant food, so that it can be given out gradually as the plants can utilize it, there must necessarily be much loss.

Reasoning along the lines indicated, I am of the opinion that in the case of pineapples, 2000 pounds of fertilizer ap