DISEASE AND NOURISHMENT

Timaru Herald, Volume CXLV, Issue 21280, 25 February 1939, Page 15

DISEASE AND NOURISHMENT

IMPORTANCE OF SOIL FERTILITY There is a curious and instructive parallelism between the affairs of plants and men. A recent reminder of this is to be found in the keen interest of plant physiologists in the so-called plant hormones and other chemical compounds present in vegetable tissues in very minute quantities at just the

time when students of animal physiology are displaying so much enthusiasm for glandular deficiencies of one kind and another, to say nothing of vitamin starvation and the like.

There seems good reason to believe that many diseases and physiological breakdowns that at present work havoc in our gardens would rapidly disappear were the plants properly nourished, and fully supplied with the various harmones. This mechanical age takes toll in many unexpected ways. One of its most vital secondary effects is that it has to a large extent deprived farms and gardens of those natural manures which at one time provided the sole means of maintaining the fertility of the soil. At first this did not appear to be a matter of primary consequence, for the machines that had robbed man of one method of feeding his land seemed themselves to provide their own answer to tire problem by enabling him to prepare chemical fertilisers cheaply and In bulk. Even now, there is no reason to Jump to the conclusion that this is not the case, but it is certainly becoming increasingly clear that the early experimenters with chemical foods had not envisaged a tithe of the whole problem. Three Chemicals Not Enough New and more exact methods of experiment have proved beyond doubt that the old “golden tripod’ of essential plant foods, namely potash, phosphates, and nitrogen, is no longer able to support the theories that were built upon it. There are many other chemicals, some of which are present in plant tissues in such infinitesimal quantities that their presence has only recently been detected, that are quite as essential to growth, health, and vitality. To give just one example: Experiments carried out during the last eight or nine years have shown the presence in plant tissues of chemical compounds, known as auxins, which have a controlling effect upon growth. It has been found possible to isolate these compounds, and supply them to plants in various ways, and the effect in most cases has been startling, particularly when it is explained that the quantities used amount to as little as one-millionth of a milligram per hour. A feature of prime interest from the gardener’s standpoint is that the source of auxins for many of the scientific experiments has been the. urine of herbivorous animals, and that it is possible for these auxins to be taken in by the roots. In other words, we are back again where we were 50 years ago, and are simply finding new reasons for the successes which our forefathers attained with natural manures. Of course, it is not possible now to oust the machine in favour of the horse, and there is certainly never again likely to be enough animal manure to go round. In consequence, it is reassuring to learn that chemists are already producing auxins synthetically .

The humus content of the soil is another matter that is receiving ever-in-creasing attention, and here, again gardeners are realising more and more how much the shortage of animal manures has cost them.