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   The natural rain-forests were one of the great surpluses of Nature but they are now alarmingly depleted and the trees are being used up at ever increasing speed. And this is the time when their restoration and expansion has become most critical for the safety and preservation of the total environment.

   The deepest soil on the face of the earth was in the natural rain forests. The forest soils were not always the most fertile when judged on their capacity to produce in abundance the feeds of the high quality complete proteins. But they were tremendously absorbent.

   Rain forests once grew wherever the conditions for their development had been suitable. They needed an adequate and regular water supply, mild to hot conditions with no long dry periods. The trees did not usually intrude into the great fertile grasslands because these were subject to drought.

   Trees and the deep soil of the forest are critical in landscape design for the city and for the countryside--in the City Forest and the strip forests for the farm and grazing lands.

   In nature the deep soil and the trees created each other because the climatic conditions were right--and no doubt they took their time about it! There is no such deep absorbent soil where it is needed for City Forests but there is need for hurry! However the responses of the inhabitants of the soil to good conditions and abundant food, are very rapid. These things can be promoted and controlled. As was said, fertile soil has been developed from poor soil and subsoil many times, in a space of only three years. For the development of the soil for the City Forest there is this difference; the objective is not eight or even sixteen inches of soil but the rapid development of four feet, five feet or more, of fertile and absorbent soil.

   The preparation of the land for water flow and for the planting and irrigating of the soil and the trees are soil making procedures. There will be no waiting around for these things to happen. The natural responses will again be rapid.

   Some experiments of the author in growing trees and experiences to do with rain forests are recounted in order to confirm the validity of the City Forest and the strip forests for their role in landscape design.

   A hundred or more trees were planted a year after the purchase of the farm, (1943). The ground was opened up with a post hole digger; the young trees were watered for a time. The planting was a failure.

   Immersed in the problems of water, no further attempts were made to grow trees for a few years. But becoming interested later in the treated round post type of fencing, it was decided to grow a perpetual forest of fence posts. This planting was so successful that in three years there were more trees ready for posts than could be used. When some of the trees were cut, a selected sucker was left to grow from each stump. They were large enough for posts in only two more years. The trees were spotted gums, (Eucalyptus maculata).

   Of course this planting had been done differently, because in the meantime something had been learned from our soil experiments.

   The poor shale derived soil, the exposed subsoil and the yellow shale was torn-up with an early version of chisel plow and sown as for a pasture and soil development programme and managed as such for a year. There was one significant change; the area was chiselled when dry enough after every fall of rain for the one year. In the successive cultivations the chisels penetrated a little deeper. The lines for the rows of trees were deeply ripped--16 inches. By the end of the year the clovers and grasses had become healthy looking and vigorous, the poor soil material now looked like soil for seven inches down and there were some earthworms to be seen. In this moist soil the young six leaf seedling trees were planted after having been watered the evening before in the tubes in which they were grown by the New South Wales Forestry Commission. They received no water at planting time and only rain thereafter. The soil between the tree-rows was chiselled twice during the year after planting, by which time the roots of the young trees had gone down over 20 inches. Two years after tree planting the soil was found to be loaded with various grain and thread-like fungi, the character of the earthworms had changed to big and fat and clover plants persisted among the trees. I had not seen such forest soil since digging in the rain forest of Queensland's Atherton Tableland before the Second World War.

   But this notable instance of soil making, which was repeated with other tree plantings, could be considerably accelerated. For instance, it was done on poor soil-material--sub-soil and shale--without irrigation and with less than an abundant rainfall. The ripping for the rows of trees was 16 inches deep; it is quite practical nowadays to rip to 50 inches and more. The depth of chiselling between tree rows did not exceed eight inches; it could likewise be ripped to 50 inches deep. Special plants would keep the earth aerated; many plants will go down to wherever the moisture is. No fungi spores were added; perhaps the best could be introduced. The earthworms arrived on their own accord; maybe the world's largest earthworms from the Gippsland rain forest of Victoria could be introduced and would grow longer than their recorded 11 feet. Very fortunately, earthworms are not over-sensitive to the chemicals of industry and agriculture. To multiply these factors there is the effect of irrigating the soil and the trees with the wonder-water from the city.

   A great surplus of fertility would rapidly develop in the soil of the City Forests. It would also physically increase by the addition of dusts from the atmosphere filtered by the leaves and washed to the surface by the rain. Other matter would be extracted from the effluents by the soil processes and by the trees themselves, to return to the soil in the leaf-fall. Although indeterminate at the moment, the surplus of top fertility soil which would be available for sale to home gardeners, and for parks, gardens and plant nurseries, would be big business. It would require 20,000 acres or even up to 40,000 acres to use for optimum profits, the waste water from a city of 2,000,000 people. A large area? Perhaps, but certainly no giant in rain forests--or in grazing properties.

   Even Sydney, a city of high priced land, has much larger areas in reserves and so-called parklands which are little seen and rarely used. True, much of it is apparently worthless sandstone shelf country. Its 'water shape' is also poor. But the requirements of the rain forest are principally a place for the trees to stand up and adequate water. Sandstone country can be cultivated, if not by rippers then certainly by explosives. We had experience of this kind of 'cultivation' in 1951. A particular contract called the removal of 20,000 tons of sandstone daily which we lifted and dumped to the side with a dragline excavator--after "cultivation" with explosives. When each 'shot' of a ton of explosives was fired, a near-by observer would hear only a dull whoosh and see the section of land lift en masse and settle back again . The surface was so little disturbed that motor vehicles continued to travel it. But no matter how heavy the deluge, no water ran off and none formed pools on the explosive-cultivated land . Incidentally this contract was planned in 1950, and designed to operate on these same principles of 'complete water control' even if the rainfall was extremely high. 1951 turned out to be the year of the "widespread big wet." The nearly incessant rain eventually closed every coal mine, both underground and open-cut, in New South Wales, while our job did not lose a day.

   There are other experiences relevant to the 'impossible' nature of sandstone shelf country. Firstly, years ago the author designed a machine to pulverise scrub, the smaller timber and the surface boulders of rock strewn rural land and coined a new word to name it, the 'tritter'. Drawn by the ordinary farm tractor, it turns at a low cost such things as lumps of sandstone into sand and dust to leave plenty of fine material to grow grass and trees. Tracks through rough country have nowadays been called "tritter trails". The tritter is marketed world wide by new owners. Secondly; sandstone country is frequently of 'poor water shape' which means that the three shapes of land--main ridge, primary valley and primary ridge--are not smoothed over and rounded off. They can be smoothed over and made suitable for rapid irrigation with the minimum of rock-moving. A cheaper and better method for constituting natural water shapes would be to use the garbage which is in plentiful supply. Indeed the garbage disposal problem could be solved for centuries to come by using it to turn the rocky gorges of the sandstone shelf country into luxuriantly forested valleys.

   This 'worthless' sandstone shelf country can be converted to deep soiled rain forests with little delay and produce as well as timber, plenty of surplus fertile soil for sale.

   In 1948 the reserved remnant of a Kauri rain forest was seen in New Zealand immediately after heavy rain had ceased. The soil appeared merely moist. The forest remnant is a tourist attraction; the forest soil appeared to be deep. It was evident that the surface of the man-made grassland which surrounded it was much lower. A notice stated also that the grassland was once forest land. The height was lost through erosion by water, compaction and shrinkage. Such a forest would take-in dozens of inches of flood-type rains and discharge it gently from springs of clear water to the streams and the river.

   Camped in the rain forests of New Guinea before the Second World War, one of the bugbears was getting wood to burn in the cooking fire. One of the most used expressions around the camps was "Wind 'im fire" which is pidgeon English for 'blow-up the fire' (to stop the stinking acrid smoke). But higher up there grew one special tree, an Australian eucalypt. When first seen I hurried to 'wash' my face in its leaves. After months in the smelly forest below, the urge was irresistible.

   The vanishing rain forests of Australia do not have the unpleasant smell of many tropical forests. For the City Forest even the perfume could be chosen by planting a few special trees.

   These natural rain-forests and others visited around Australia, the two islands of New Zealand, the Pacific Islands, Europe and America; wherever they remain, have in common the great water absorbtion capacity to stop any amount of rain-fall in its tracks; to take in water very quickly and to release it slowly in springs of clear water. A region which is covered with good grassland soil does not produce heavy floods, but covered with deep forest soil floods are not possible. Flood control is merely one coincidental of landscape design. There is another that would belong to the City Forests and is even more significant; they would be fire proof.