HOW MAN MAKES DESERTS.

Waikato Times, Volume 121, Issue 20272, 14 August 1937, Page 15 (Supplement)

HOW MAN MAKES DESERTS.

Soil Erosion in the British Empire

(Elspeth Huxley In London Times)

THE SOIL EROSION menace in North America has been so widely dlsoussed and lamented that we have begun to realise, even In this fortunate 'uneroded land, how much Irreparable damage has already 'been done In the United States. First dust-storms, then floods, provided demonstrations on a grand scale that, If man persists In misuse of the land, sooner or later he must pay a heavy penalty, it Is perhaps less widely realised that exactly similar processes of soil erosion are at work In many parts of the Empire. Erosion damage has reached so acute a stage In Basutoland that the Colonial Development Fund recently made a grant of £162,000 for the construction of antt-eros-lon works. The scheme now launched in the Protectorate, which Involve* the building of numerous conservation dams to arrest the spread of gutters and to provide watering places for stock, will be only Just In time to Save Large Areas From Ruin. The greater part of Africa is, In fact, very subject to erosion. The process, through centuries, has robbed the continent of vast acreages of once productive soil. We are apt to think of deserts as the creation of Nature, like seas and mountains, in whose origin man has no say. But deserts are to a large extent man-made, the product of a dislocation in the balance of nature due to human intervention. Under natural conditions soli is protected from the erosive action of wind and water by a covering of vegetation—forest, bush or grass. When vegetative cover Is stripped from the land, a proportion of the rainwater, instead of sinking in, runs off the surface Into streams and rivers and Is lost; and in hot countries more still disappears through evaporation from the unsheltered earth. In due course the underground water store diminishes, the water-table falls, and streams, fed by dwindling springs, shrink In ; volume and sometimes cease to flow at all, , except when temporarily fed by heavy storms. On these occasions they rush down in sudden flood, carrying with them huge quantities of i Valuable Topsoil and Plant Food. , A rlvcvr in Wisconsin, for Instance, which \ normally carries one ton of silt a day. was found to wash down 8970 tons in a single { hour after heavy rain In the catchment There Is a familiar situation In Africa, j where water supplies are perhaps the great- . cst limiting factor In development. The continent is scarred with dry river beds that ‘ must once have flowed all the year round. £ One day the much-abused tsetse fly may be honoured, like the cotton bollweevll, by commemoratlon in a statue, erected as a tribute to Its great work as “guardiau of the waters.” For the tsetse fly, by keeping cattle away, has protected land alike from overgrazing and from cultivation, and so . preserved vegetative cover and ensured the even flow of streams. In certain areas, no tab! v Tanganyika, Governments are conducting large-scale campaigns against the tsetse. The success of such measures cannot fairly be judged tin til their effect on water supplies have been observed 20 or 30 >ears hence. For the past century in Africa vegetative cover has 'been slowly but steadily stripped a from the land, and the process continues to-day at an accelerated rate. Only about f to per cent, of Africa is under trees; the right amount, for the safety of soil and of I water supplies would be about 30 per rent J The growth of population that Is taking place I means that More Cultivated Land Is Needed the drives Which nearly all Colonial 1 Govern ' menu have undertaken In recent years to I Like in..si excellent aims, this increase In ‘ !"|. soil. S.mie other European efforts to enlighten I like agricultural boomerangs. The tradi- ' tioiial African method of planting for m- • stance, is to sow all the crops haphazard In 1 one field —beans, field peas, sweet potatoes, «

maize, yams, all mixed up together to form a fairly thick anti-eroslve mat o\er the soil surface. From Europeans the native peasant has learnt to plant crops singly and t » plant In rows, thus leaving the soil far more Exposed to Erosive Influences. Another Improvement that needs to be watched is the introduction of the plough. Ploughs enable land to be laid bare In large blocks, which a.re far more susceptible to erosion than the small “gardens.” dug with a broad-bladed sword, of native tradition. To hesitate over introducing Improvements like the plough, or over encouraging increased native production on account of the dangers involved, would, of course, be a defeatist policy, even if it were a possible one. What is needed is a more carefully thought-out plan of progress. The advent of European rule in Africa has tipped the scales of Nature’s balance which normally maintain an equilibrium between livestock and the land. Rinderpest has been controlled bv double Inoculation. East Coast fever localised by means of dipping, and other diseases overcome. And the cessation of tribal raiding has put a stop to once frequent migrations, so anchoring stock populations to limited areas of grazing In a manner unknown before in history. The result has been an immense increase In the numbers of cattle and goats, unaccompanied by any corresponding increase in the carrying capacity of the pastures. A case in point is the Kakamba reserve In Kenya. The cattle population is estimated at 250.000 and the present carrying capacity of the land on which they exist has been put at 20,000. The result is that the pastures have been trampled and over-grazed to such an extent that grass lias been killed, bare land exposed to the elements, and erosion in its Acutest and Most Rapid Form has set in. Conditions In the Wakamha reserve are typical of those tn other parts of Africa and hi other continents a* well. About 58,000,000 acres of “range" land in the Pacific North-west of America are estimated to toe so badly injured by over-grazing that they can now carry only ene-flfth of the stock they were originally aide to support In South Australia several millions of acres which carried sheep 10 years ago have been degraded by persistent overstocking into a desert devoid of vegetation and abandoned for good. The damage done by cattle and sheep, however, Is mild compared with what can be done by goats, it would not be exaggerating to describe these prolifl.- animals as the curse of Africa. They are said to have destroyed the fertility of ancient Greece, and they are well on their way to wards repeating their grisly triumph over the vegetation of Africa. Th«*v eat not only grass but bush, roots and bark. No young tree nr shrub can establish IKo|f where goats are allowed to browse. Economically useless —the common African co.at has \lrtuallv no commercial value—they do not even rare occasions, with meat. In the old days a fair number were kilted for rellcfous or of education and Christianity has virtually put a partial but once significant form of go,t control. The limitation of stock Is admittedly a Complex and Difficult Question, * for If reaches down to the foundations of African belief and custom. But >j..rk must level. A survey of erosion In Hem a In now toolna made by an agricultural officer* seconded for the purpose, and .» *• Imme f.>r t' e reconditioning of the Wakamha r-s.-nc, combined It is estimated to e,,>i spread over