THE RUBBISH HEAP

Wairarapa Times-Age, 16 December 1938, Page 11

THE RUBBISH HEAP

TWO SIDES OF THE PICTURE.

With the arrival of autumn, every gardener finds that in some remote corner of his land an unsightly mound of lawn mowings, fallen leaves, dead twigs, weeds and general sweepings has accumulated.

It is usually the custom to light a fire under this heap when it is sufficiently dry, choosing a day when there is a little wind, and let it smoulder until nothing but a small residue .of ash remains, which is useful as fertiliser owing to valuable potash which it contains.

This system has doubltess much to commend it, as it get rid of a heap of rubbish which, if left unburned, is an ideal winter refuge and later a breeding ground for many of the insects and pests which in the following spring and summer will cause considerable damage to the growing crops. By setting fire to the pile all diseased branches, larvae of insects and an unwanted accumulation of refuse is done away with in a simple manner. Hence the popularity of the practice. There is, however, a reverse side to the picture which is equally if not more important. The heap consists of dead and decaying plants or parts of plants, all of which have taken considerable amounts of nourishment from

the ground on which they grew and consequently have impoverished the soil to that extent. If allowed to rot throughout the winter the pile would form an ideal manure for the following year's crops, as it would return to the soil just those constituents which were extracted from it; that is, the essential foods which are necessary to plant life. The most potent argument against adopting this method is, of course, the one already quoted—that by so doing the grubs and caterpillars which have emerged or will emerge from the larvae on hatching are returned to prey upon the young crops and thereby cause unnecessary trouble and expense to the grower. On the other hand, the practice of setting the rubbish heap alight is an extravagant one, as all the nitrates and phosphates contained in the decaying plants are burned up and escape into the air in the form of gases, thus causing considerable loss of valuable plant foods. As already pointed out, only the potash remains in the form of ash. An even more serious loss is that all the organic matter, known as humus, is also decomposed and carried off into the atmosphere in the form of smoke, and humus is just as necessary to plant growth as nitrogen, phosphates and potash. A soil (such as sand, clay or calciferous land) which lacks humus is said to be hungry, and no amount of dosing with chemical fertilisers will supply the deficiency. It is humus (plentifully found in rich loams) which supplies the carbohydrates (sugar, starch, cellulose, etc) which go to make up the sap and tissues of plant life and without ample quantities of which no plant can thrive. Now that the principal advantages and disadvantages of setting fire to the rubbish heap have been outlined, it remains to find some solution of the problem by which the plant foods contained may be saved without returning to the land the injurious insect pests which it harbours. The method adopted involves a certain amount of time and work, but the result obtained will amply repay the outlay of energy. In the first place, no disease leaves, twigs or branches of trees should be thrown on the refuse pile. A separate heap should be made of these and they should be set alight at once to destroy the pests and their eggs. A pit about a foot in depth and of a suitable area, according to the amount of refuse ■ which is likely to accumulate, is dug and the bottom is covered with a layer of rubbish. This is sprinkled with a chemical preparation known as an “accelerator” which will hasten the process of rot-

ting of the vegetable matter. These socalled “accelerators” are usually composed of some mixture of superphosphate, sulphate of ammonia, or nitrate of soda and equally good results can be obtained by a home-made mixture of three-parts superphosphate, and two parts sulphate of ammonia. These can be mixed in this proportion or applied separately in similar proportions. The quantity to apply does not actually matter, but sufficient should be applied to permeatethe heap. It mtisf'be remembered that there is no loss, because however much is applied is retained by the compost and eventually finds it way back to the garden. The best way is to prepare the heap, and every eight inches of refuse when firmed should have about five ounces of the mixture scattered on each square yard of surface.

Further layers of rubbish are added from time to time as made —each successive layer being sprinkled with the mixture. It should also be well watered. If the ’“pie” settles down and becomes too compact it should be forked over to loosen it up so that the air can penetrate, since plentiful supplies of moisture and air are requisite for decomposition of the vegetable matter. If the mass is allowed to get tqo solid the air will not find its way through and thus when the contents of the “pie” are dug out for manurial purposes the following sprin, the refuse will not have thoroughly rotted.