AERATION ALL IMPORTANT.

Northern Advocate, 1 September 1888, Page 3

AERATION ALL IMPORTANT.

. By Profesxor E. S. Moff. In the Mediterranean regions the steep mountain slopes and hillsides are terraced for the culture of oranges, lemons, and 6lives, and these terraces are held in place by rough stone walls, laid up without O^ortar or cement. Behind these loose walls, trees, shrubs and vines are grown with the greatest success, as they have been for centuries. A wealthy English gentleman who spends his winters at Mentone, on the shores of the great subtropical sea named above, thought to improve xipon the customs of the oountry by building his terrace walls of stones laid in cemment. But, to his surprise, his tiees made a feeble, sickly growth, and bore miserable crops, while those of his poor peasant neighbours growing behind dry and often dilapidated walls, were models of health and productiveness. The removal of some of these walls brought to light a most important fact in agriculture—the necessity of soil aeration to the healthful growth of roots. The rear side of the loose and dry nibble walls was completely closed with a mat of finely interlaced root fibres from the fruit trees growing on the terraces. This mat followed down the walls, clear to the base, and extended to a considerable distance, horizontally, in both directions, thus a large surface was exposed to the beneficial influence of the atmosphere. Behind the cemented walls, however, no such root development was found. The rootlets spread out somewhat beneath the surface of the narrow terrace, but failed to follow the walls downward. The cemented walls had shut out the oxygen, and there was no encouragement for root growth. The trees were restricted in their nutrition, and a depauperate growth was the result. In my experience in washing out roots of various plants at our New- York State Experiment Station. I have been often struck with the faot that the roots of crops spread out over the surface of the layer of soil that lies just beneath the plough-line, as upon a table. The roots are almost exclusively in the lower three inches of the soil moved by the plough. The loose surface layer of soil corresponds to the dry rubble wall. Beneath it is the mat of roots. Every florist finds the mat of roots always close to the inner wall of the pots. If he uses a glazed pot the plants do not prosper, the roots being deprived of the influence of oxygen. They are in the same condition as were the gentleman's trees growing behind the cemmented walls. The moral is obvious. We must keep the surface soil loose. We are admouished to do this in order to prevent evaporation, but this is but half of the argument, as the illustrations to hand bo clearly show. Nature in some mysterious way provides for her own aeration. Go into the woods where the soil supports a vigorous vegetation and take up a spadeful of earth. It will be found fully as porus as the most thoroughly cultivated field. The sod ground along an old fence, though not disturbed by the plough, for half a century, is always porus and friable. But in cultivated fields, where we disturb natural processes, the soil becomes compacted, unless kept loose by tillage. How then can we expect a good crop from a baked soil, or a good yield of fruits from trees in land packed into a hardpan by cattle or swine ? The same truth is illustrated in cities where shade trees refuse to grow along paved streets.