SLEEPERS AWAKE!

New Zealand Listener, Volume 13, Issue 317, 20 July 1945, Page 6

SLEEPERS AWAKE!

Geeographer Sounds An Alarm

SOIL EROSION IN NEW ZEALAND: A GEOGRAPHIC RECONNAISSANCE. By KENNETH B. CUMBERLAND. Published by the Soil Conservation and Rivers Control Council, OOKS and booklets on erosion will soon be as numerous as the experts on the subject, and as hasty in their generalisations. But there are books and books, and this one is in a class by itself. It is an amazing book, impossible to read without a dictionary, but so earnest, so exhaustive, so convincing, and so thoroughly disturbing, that to treat it lightly would be to aid and abet all the carelessness, ignorance, and short-sighted greed that have caused it to be written. Fhe first thing to do in considering erosion in any country is to look at a relief map. The next is to study the covering of the land; and the next its geological foundations. With these we must consider the climate partly as a consequence and partly as a cause; and when Mr. Cumberland does that he finds himself looking at seven different Regions in New Zealand, all with different erosion histories: . Auckland and Coromandel Peninsulas. . North Island Mountain Axis. . Taranaki, Wellington, and Hawke’s Bay Hill Country. . South Island Tussock High Country. . Central Otago and Mackenzie Inland Basins. South Island Foothills and Downland. . Canterbury Plains. NA GAA WH It is impossible in our space to illustrate what is happening in each Region, but he is a complacent New Zealander who has not already begun to be uneasy. The trouble of course is that most of us have never thought of a landscape that is not eroded. The people of New Zealand have been reared in the midst of unnecessary losses of soil and become so accustomed to their presence as to take little heed of them. They have often come to consider soil erosion as a normal, unavoidable occurrence, It has taken the experience of the United States, South Africa, and Australia to reveal to New Zealanders the seriousness and extent of the problem before their very eyes. It is only as the youthful, vigorous nation emerges from its hectic easy-going childhood to saner, steadier adolescence, that it is beginning to appreciate the more undesirable consequences of a youth at times wantonly misspent. Me: CUMBERLAND is not a New Zealander but an Englishman, and to. his fresh eyes the situation is in some respects worse than it is anywhere else in the Empire. It seems highly probable that New Zealand, the youngest of the British Dominions, has a soil erosion problem of greater significance in its relation to the future well-being of the country than has any one of the older members of the Commonwealth. The superficial area of New Zealand is small: its history of European occupance and exploitation short. The national economy and the individual living standards of its million and three-quarter people reveal an emphatic dependence upon a restricted range of export commodities-all derived from the utilisation of the soil. And New Zealand has few other significant resources. a HAT is how the menace strikes him in general. Here are some particular aspects of it. REGION 1.: , It is only from the air that one is afforded an accurate picture of the extent of the moving sand area of Region I, The eastward

migration of sand has already reached twothirds of the way across the peninsula north of Waipapakauri. Here, though, it is invading but little used scrub and swamp land and filling scattered lakes. In other places the sand is constrained in its inland march by steep hill country adjacent to the coast. In such situations, however, it has already climbed up more than 400 feet and swept over the northern and southern flanks of the hilly obstruction. On the northern head of the Hokianga Harbour, golden-yellow sand has, within living memory, climbed over a 400 foot ridge of limestone and crept down the leeward flank to tumble over low cliffs into the harbour near Rangi Point. In its surge inland over scrubland and farmland the sand has buried and killed all vestige of vegetation. Occasionally strong winds from other than the prevalent westerly direction lift off the sand and expose gaunt and ragged surfaces of naked limestone. In certain localities the frontal advance of the golden surge is to be measured in hundreds of yards per decade. Near Rangi Point sand has, in 25 years, destroyed all trace of one farm with its homestead, build- ings, fields, fences and orchard. REGION IL: Between Willowford and Kuripapanga on the Inland Patea road, the disastrous effects of sixty years of sporadic, extensive pastoral occupance of the Kawekas is clearly and indelibly written in the landscape. On the outer, easterly slope at about 1800 feet, in a region drained dendritically by right bank headwaters of the Tutaekuri and most appropriately known as "the Blowhards," is a 2000-acre man-made desert, completely stripped of soil and subsoil to a depth of five or six feet. This deep removal of material-jointly by wind and water -is revealed by the depth of sod bank marking the sharp boundaries of the "desert" and the grassed island patches (stacks) out in its centre. The peripheral bans and central stacks reveal over six inches of, chocolate-grey silt loam on nine-inch harder (projecting) layer of darker, finer-textured material on yellowishbrown silty clay. Over a wide area much of the horizon has gone. The surface is often streaked from north-west to south-east with sand which frequently scurries over the clay. The exposed subsoil is often cracked and the drainage outlet of the "desert"? is fretted with incipient gullies. Above, manuka and fern-ridden paddocks, ineffectually enclosed by dilapidated fences, climb to the crestline with its golden subsoil patches exposed by wind and water and gullied down to the greywacke bedrock. REGION IIL: As elsewhere, fire was the principal weapon used in the long, intermittent, unfinished struggle to establish pastures in place of fern (and later of manuka) in a habitat naturally productive of forest. Sheep were a subsidiary arm. ‘Fern crushing’ is discussed ‘briefly elsewhere. There are few parts of the region which, during this struggle, have not been swept frequently by fire and overgrazed by sheep. When even Guthrie-Smith, naturalist, author, and undeclared soil conservationist, can claim that "few sights are more engrossing, more enthralling, than the play of wind and flame" or that "a fire on a dry day in a dry season is worth a ride of a thousand miles," one suspects that the soil often suffered unnecessarily or at least*inadvisedly at the hands of less enlightened station holders. To-day, outside the well-grassed districts, danthonia and browntop pastures of ‘varying productivity occupy the greatest area supporting semiextensive sheep rearing activities. R take this passage about the Esk _ Valley, which, instead of being eroded, was buried in 1938 under eroded material from the hills behind it: The lower Te Ngaru Valley flat is still occupied by a spread of silt and rock with tree stumps, telegraph poles and willow trees all buried deeply in debris. The present road is. newly constructed above its former site. There are abandoned houses and the landscape is generally one of decrepitude. The Tangoio school is a new structure out on the silted flat. For neighbours, it has two or three e erect, lone, derelict chi y stacks-t ts’ of former habitations washed away or silted out-and a few Maori hovels with maize and potato patches on the new brought "soil."" The placid, wizened Esk is now crossed by a temporary bridge (continued on next page)

(continued from previous page) while a new structure is being erected. Along the Esk valley road, silt is feet high along its margins and logs are cluttered around stout, old, partly silted willows. Blue gums look disproportionately short and stumpy. Side roads are of silt-loose, yellow-white and wavy. All fences are new; old fences are buried with the old road and are only infrequently to be seen. A petrol pump is now buried deep with a flower garden laid out around the glass bowl on top of it. In the lower Esk valley, 1750 acres were in 1938 silted up to an average of at least three feet six inches and a depth of six to ten feet has been found over wide areas. One estimate (probably high) puts the soil loss over the ninety-three square miles of the Esk catchment at seven and a-half inches (solid). It is little wonder that station holders complain of the deterioration of their swards, that they are unable to get a strike of surface-grown English grasses, that the countryside is intrinsically worth less for grazing purposes than in 1870-80 and that despite the bringing in of new areas from fern and scrub and despite top-dressings, better management and increased knowledge of stock, carrying capacity remains barely stationary. The brief, exciting and eventful century of European occupance-and especially the latter half of it-has added much to the New Zealand landscape and taken mucia away. Not all that has disappeared has done so to the Dominion’s lasting advantage: nor have all the additions been wholly desirable ones, Yet, in any case, the additions-amongst them the undesirable and ugly forms of soil wastage-do facilitate the regional differentiation of New. Zealand’s area. OR will the author agree-and he is ‘a bold man who disputes the point -that erosion is confined to bushcleared areas. Here is a passage from his survey of Region IV., the high tussock country of the South Island: In essence, 80 years of pastoral occupance have decreased the vegetative cover and exposed the soil. Only rarely now do individual tussocks touch their neighbours. In many parts, tussocks reduced in size and vigour lie yards apart. Fire has not only diminished the volume, variety and vitality of the plant cover, but, equally serious, it has devoured the brown dead quilt of rottimg growth, which, in its primitive state, was a significant, if not conspicuous, feature of the’ tussock terrain. Persistent over-grazing-by both sheep and rabbits-of a vegetation of continually declining density and diminishing carrying capacity has assisted fire in exposing the sparse and discontinuous soil mantle. Both burning and grazing have assisted in undressing the soil and baring it to the ravages of the more ¢xtreme weather elements -especially to blowing by strong dry winds,

heaving and prying by frequent frost and scouring by locally-confined southerly (cold front) rainstorms. F you say that there has always been erosion-that our South Island high country was slashed and cut about before a white man ever saw it-you are no doubt speaking a part of the truth. Here is another part: What the high country folk’ call "guts" or "gutters" — deep steeply-inclined gullies — are the most striking forms of soil. wastage through the agency of rainfall or snoW-melt. There is little doubt about the absence under primitiveunburned, ungrazed, untenanted-conditions of "gutters." All those examined have, at most, an age of little over forty years. The vast majority are far more recent; they have all the sharp, clean-cut marks of youth and freshness. Nor any have been seen healed or healing; and their counterpart in the pre-pastoral period seems to have been the shallow and gentle, broadly V-shaped and sodded drainageways now sometimes the site of shingle slides. VEN in the foothills and on the downs the soil wastage is continuous. This paragraph deals with Region VI. At Heathcote, in a.3¥-acre enclosure with an 11 per cent. slope, it took but eight years of arable cultivation and intensive market gardening for sheet wash (and. plough-hastened creep), to bury completely a five-foot fence and create a rounded bank eight feet high overlooking the field below. When both enclosures were subsequently put down in lucerne, no fence was needed to prevent dairy cattle moving from one to the other. Eight years previously there was no break of slope. (Under lucerne there is no appreciable erosion.) Nor is it unusual, when prolonged and gentle early spring rains are followed by a rain of some intensity, for thotsands ef young tomato plants to be uprooted and washed out. Winter rains, too (coincident with the peried of intense soil preparation and early planting), have been known to scour hillside potato soils at Governor’s Bay, wash out soil and sprouting tubers and pile both thickly against base fences. UT, you may say, New Zealand is not all hills and mountains and gullies and precipitous gorges. There are some extensive flat areas, and erosion is not a problem there. Well, Mr. Cumberland does not agree with you. This is from a chapter about the Canterbury Plains: When the Highbank estate was subdivided in the ’nineties, five-foot deep banks of windblown topsoil were found to have accumulated under, and immediately to the lee of, Pinus radiata shelter belts then barely 20 years old. Along the line of one plantation, now being cut out, a mound of some 1400-1500 cubic yards of wind-blown silt occurs within a distance of 300 yards. In another instance, a similar bank of topsoil was respread in a 50-yard-wide belt immediately to leeward of the

plantation, as a result of which the "topdressed" strip yielded almost 60 bushels to the. acre of Velvet wheat in two successive years. This was over twice the yield per acre from the remainder of the enclosure the first year, and three times its yield in the second year. You may, if it comforts you, call him an alarmist: he would probably reply that he would be ashamed not to be. There would be something wrong with him if he could remain undisturbed in the presence of the facts as he sees them. Even ignoring the depredations of wild ani-mals-deer, pigs and so on-in the unoccupied tracts of the country, not less than twentyeight million acres in the Dominion (and possibly many more) are inflicted with the disease of culturally accelerated erosion to a degree which justifies national concern. This is more than two-fifths of the total area of the Dominion and more than two-thirds of the area in occupation. Proportionately, New Zealand has a soil erosion problem as great as that of any other nation-if not greater. Moreover, soil erosion occurs within the limited area of New Zealand in a great variety of forms. It occurs in different ways in different regions. Some regional combinations of forms are unique: some individual forms are extremeiy unusual and appear most difficult to arrest and counter. AS he then a remedy? Yes and No. He is in no doubt about the cause; but if a man loses an eye or a tooth we usually know why. There are some calamities that cannot be overcome

however humbly we admit our responsibility for them, and some things have happened to New Zealand already that our children’s children will still be paying for. But the position is not at all hopeless as a whole if we wake up in time, and it is not Mr. Cumberland’s job to tell us what to do when we have at last recovered our senses. He does offer sane, cautious advice: et Research so far conducted has had reference solely to the restoration of vegetation, and, valuable as this would be in saving soil, no effort has yet been expended with the acknowledged and primary object of arresting soil erosion. The restoration of vegetation mignt well be facilitated for example, if attempts were made at water conservation-that is, if a broader approach were adopted to the many inter-related land problems. Many decades ago gold miners found it possible to construct hundreds, of miles of water-races and thus to carry water for sluicing purposes. It should.‘be pos sible in these days of elaborate digging, ditching, excavating and earth-moving machinery to convert these water channels and construct many others in order to contour-irrigate, the depleted pastures of easier slope as a first step towards improving the moisture relations of the soil, restoring the plant cover and saving soil. Similarly, experiments with contour furrowing are necessary. . y FINALLY he is careful not to leave us with the impression that erosion is a farming sin only, and that farmers therefore can be left to cope with it: (continued on next page)

EROSION IN NEW ZEALAND

(continued from previous page) The future health of the nation-and of the world-is tied closely to the futute health of the land. As a nature we require to renew our acquaintance with, and regard for, the soil, and reaffirm our: faith in its continued and enhanced productivity. We need to pledge ourselves to its care and proper treatment. Every citizen is concerned in this; no New Zealander can escape its implications. Productive soil is the life of the Dominion, though we often overlook the fact. With each: passing year-as the accompanying photographs alone adéquately demonstrate-this soil is vanishing. Not only the farmer but also the banker, the trade unionist, the miner, the slaughter-man, tne teacher, the mechanic, and the retailer: ail have a personal stake in the urgency and the thoroughness which we accord to the formulation of plans for conserving and developing Ss)

land, and a personal stake likewise in the ‘speed with which this and other nations move to these tasks. To defend the Dominion’s soil resources and cure their ills is not merely to ensure permanent farm and station production. A coniprehensive programme of wise land use implies also a resuscitation of rural life. It wiil make of farming a way of life rather than a means of making a living. It will tend to check the already noticeable and excessive urbanisation of population. It means more intensive use of better land, closer subdivision and room for immigrant farm families. Soil conservation has, too, its aesthetic as well as economic advantages. Tourism will remain of significance to Néw Zealand only if its scenic «attractions are preserved. In recent years they, too, have deteriorated. In helping to ensure nations of healthy, happy and contented people, soil conservation -‘"the most significant movement in agriculture in the Christian era (and) an advance in civilisation not, fully to be appraised for generations’’--can go far towards making possible social security in the widest sense in all nations and in establishing and guaranteeing the permanence of better international relationships. ND there are of course the illustrations, for Mr. Cumberland is not content merely to talk to us. If our ears will not hear he is determined that our eyes shall see, and so has assembled (or had assembled) the most arresting collection of erosion photographs ever brought between two covers in New Zealand. You see some of them in this article-five out of 50 or 60, But some of the most alarming could not have been reproduced without loss of detail, even if the space had been available, and single photographs in any case convey only a faint impression of the massed effect of 20 or 30 pages. CO RR ne te nn a a ee LT