THERE is every indication from my own work in developing theKeyline plan on "Nevallan" that tree belts, where located in respect toland shape, are of tremendous benefit to land and have no disadvantages to the developmentand maintenance of a highly fertile soil in a stable and permanent landscape.
There has been a great new interest in the function of treeson the farm by all types of people and by many authorities recommending tree planting.In no instance do these recommendations include any logical method of placing treesand tree belts for their most beneficial effect on the land.
In New South Wales trees have been cleared from most land forall types of agriculture, but in no circumstances is the complete clearing of a propertynecessary or justified. Trees, even odd trees, by greatly restricting the area ofgrass growth, have caused farmers and graziers generally to aim at the complete destructionof all trees on grazing and farming land. But in clearing operations, when treesare left in properly located and designed belts, the land which they occupy willnot reduce farm productiveness; rather they will add to it.
I have noticed on our own properties that tree belts which wereleft on country that had been badly eroded, abandoned and covered with only the poorestregrowth of trees, had the effect of restricting moisture and pasture growth nearthe tree belts. This was an effect only for the first two years of our Keyline developmentprogramme. From that time onwards the trees had a beneficial effect on the pasture,and the notably best pasture in a dry winter growing near the tree lines.
On much pasture land often it is only the old trees that areleft, hence the concentration of stock around the trees causes bare patches of soil.But when the trees are left in properly-designed tree belts there is more than enoughshade for all the stock.
There is a very marked improvement in the soil in the tree linesafter the second year. On the edge of a tree belt on "Nevallan" there isleft a larger than usual fallen tree, which was pushed down in 1951 as part of theclearing operation. It was left as it fell and not disposed of because it was tooclose to the trees. The operation of moving it would have destroyed the small treesin a place where there were too few in the tree belt. It has been lying there eversince, with the subsoil and shale in which it grew still firmly held in its turneduproots. It has been a good illustration of the soil which we started to develop, withnow a wonderful contrast of deep dark soil beneath the pasture nearby. Thousandsof people have seen it. A wind storm in 1954 uprooted a tree a few yards away. Thecomparison of the deep rich soil held in the roots of this tree, almost incrediblewithout having been seen, illustrates how rapidly soil can change and develop. Theonly factor influencing the development was the changed soil moisture of the treelinewhich was caused by the three years of Keyline soil management in the pasture areaabove the treeline. The longer-lasting moisture promoted in the tree belt by thework above it changed the soil of the tree belt. Formerly only subsoil and shale,it is now deep fertile soil. There was no cultivation in the tree belt, no fertilisingand no grass planted.
Many people whom I have shown around "Nevallan" seemdoubtful of my statements on the rate of growth and the increasing thickness of thefoliage of our trees. Whenever I hear doubt expressed or sense a doubt I invariablyglance around the group for a copy of "The Keyline Plan". Hundreds of copiesof my book have been carried to "Nevallan" by visitors, who find greatinterest in identifying on the property the pictures in the book. Then we walk tothe camera site of one of the book's pictures and everyone becomes interested inthe convincing comparisons.
The healthy condition of stock is assisted by adequate shadein the summer. The tree lines have a beneficial effect on all the soil by retardingthe drying effect of hot winds and ameliorating cold windy days.
Tree belts, since they are cooler in hot summers and warmerin winter, help to maintain the constitution of farm animals. There is little apparentbenefit from trees for two years, but from the second year onwards the tree beltsdevelop into moisture reserves and into great fertility reserve's from the droppingsof the animals. As moisture and fertility spread fast downhill, the belt of treessoon has a beneficial effect on much of the pasture land below it.
In wet weather the better conditions in the tree belt encouragestock to stay on pasture only a sufficient time to feed, thus keeping them for longperiods in the tree belts and off the pasture, and preventing trampling damage causedby stock roaming on wet soil.
If a farm is to maintain an increasing fertility in its soil--acomplete fertility in a progressively improving landscape--then trees will be necessaryfor their continuous turnover of the deeper elements of fertility. They may drawthese from great depths in the earth and shower them back on to the surface as leaffall. The deep minerals they supply soon become incorporated in and form part ofthe soil.
The selection of the tree species must logically be based onthe climate, the type of trees that will grow in that climate and the progressivelyimproving environment. The pattern of any tree planting is always based on the shapeof the land. Farm roads and water supply features also influence their location.
It may be argued that a farm earth-wall dam is not as permanentin its life of usefulness as a tree belt, but the location, design and constructionof farm irrigation dams in Keyline are such that they remain permanent agriculturalfeatures. The tree belts bordering the roads on "Nevallan" are not onlybeneficial but add to the beauty of the landscape.
Trees are placed in the Keyline scale ahead of permanent farmbuildings because their lasting qualities exceed those of the buildings. How oftendoes one see a group of trees in an area where a farm homestead once stood?
While the general design of clearing and tree planting is basedon climate, land shape, water supply and farm roads, trees should be planted as partof the site planning for the whole farm.
The remainder of this chapter is substantially what I wroteon trees in "The Keyline Plan" published in 1954.
On uncleared land, where the initial trees had value as timber,all these trees were part of the environment which produced the soil. In no circumstancesis the complete destruction of all timber trees and the associated smaller growthnecessary or desirable for farming and grazing pursuits.
There is probably no other land development work that has beenso completely unplanned and haphazard as that of timber killing and clearing andno factor of fertility so completely ignored.
In order to grow crops and pasture on forested country clearingof some timber is necessary. Gradually more and more timber is cleared because ofthe disadvantageous effect of trees on crop land. However, like some methods of cultivation,clearing has been overdone, with the result that soil fertility eventually sufferedand crop and pasture yields were affected. Sufficient trees on a property may make,in some circumstances, all the difference between a good farm and abandonment. Grassesand timber do not usually grow well together. A large tree will all too often affectquite a sizeable area of crop or pasture land and the tendency is to get rid of thetree. On some farming lands trees are left scattered about. These trees, no longerliving in forest conditions, tend to die out. It is often observed that the upperand outer branches are dead and groups of trees are slowly dying. On some farms theyare already dead.
Properties containing some steep country have often been clearedto allow all the flatter country to be cropped. The steep land is left timbered andused for grazing purposes. The general practice of leaving all steep country in timberto protect it from erosion has not been successful. This is certainly true of Australia,and the practice has not improved the timber. Steep country left fully timbered isoften the greatest bushfire hazard and the worst area for pests. One heavy rain followinga fire in a timbered area moves the poor soil quickly and often to the stage of guttering.
To derive the greatest benefit from timber for soil fertilityand better farm working and living conditions trees must be left to serve the wholeof the property. Properly located trees cool a farm for stock in summer and warmit in winter. They protect the land from winds and in their widest aspect may becapable of some overall improvement in climate. Keyline timber clearing is plannedto derive the greatest benefit from trees for the whole of the farm.
First, trees are left in strips or belts wide enough to keepsome semblance of forest conditions in the timber for its normal healthy growth.
Steep country is not left in full timber but partially clearedto plan with timber strips left to serve as wind protection for the property.
The Keyline is again the planning guide for clearing. The firsttimber strip twenty to thirty yards wide is left immediately above or below the Keylineand forms a Keyline timber strip--our basis for planning in clearing operations.From the Keyline both up the slope and down the slope of the land timber strips areleft (or planted) on the contour or on a slight grade to suit the overall Planningand at selected vertical intervals apart. The important guide for determining thisvertical interval between timber strips is related to the height of the trees. Iftrees are forty feet high and the vertical height occupied by the land in the widthof the tree belt is ten feet, the timber strips would be vertically fifty feet apart.This provides very effective overall wind protection for all the land and locatesthe timber strips closer together in the steep country and farther apart as the countryflattens. Even in very flat country of low scrub or mallee only ten to fifteen feethigh, a similar formula for clearing will provide greatly improved farm conditions.
Timber strips left as described are a valuable aid to soil fertilityapart from the supply of the deep minerals which they bring to the surface. In wetweather cattle will only stay on soft pasture ground long enough to feed and thenreturn to the firmer ground in the undisturbed soil of the timber belt.
The two most efficient land compacting implements are the sheepfootroller and the multiple pneumatic-wheel roller. The farmer has to contend with hisown efficient compactors which are his stock and wheeled farm implements. The comfortableconditions of the timber strips will, to a large extent, keep his stock off softwet ground. The farmer, of course, should leave his wheel machinery in the machineshed when the land is wet. Thus compaction of the soil, one of the great destroyersof soil fertility, is minimised.
By clearing the steep country on this pattern more and bettergrass areas are available and better timber will grow in the timber strips. Veryshort steep slope country is always of greater value when cleared and Keyline developed.Suitable timber strips are left on the flatter top country above.
Keyline absorption-fertility methods above the timber strips,by the greatly increased moisture-holding capacity of this land, provide the timberwith better moisture. Timber growth is considerably accelerated.
Timber strips are the only completely satisfactory means ofpreventing land slips on country that would tend normally to slip when fully clearedand saturated in heavy rains. The timber strip is a definite and effective anchorholding the land shape.
Land that has been Keyline cleared and subdivided into paddockswill have some shelter timber in all or most paddocks. Every paddock, whether inthe steeper slopes or the flat country, can be rotated in turn to grasses and crops.
The only way to ensure perpetual timber is by providing conditionsthat allow trees of all ages to grow together. If each paddock in turn is closedto stock and cropped for three or more years, young trees develop in the timber stripsand permanency of timber belts is assured.
If tree strips of even width are desirable, then a contour line,or grade line, forms the lower line of the strips above the Keyline. A line, parallelto this, forms the upper line. Below the Keyline the upper line of the strip is onthe contour or grade line and the lower line is parallel to it. The exception isnear the irrigation drain line where the timber strip is above the drainline.
A strip of trees is also left around the boundary of any suitableland area.
There are other considerations in maintaining tree belts. Noland could be more spectacularly beautiful than the timbered undulating country ofAustralia when it has been cleared and developed by Keyline planning. However, largeareas of land which will come up for Keyline development have had too much of theirtimber removed without plan. The growing of timber strips now will be a necessarypart of the best Keyline development.
Generally a small Australian native tree will cost a littleover one shilling to plant but may cost over one pound to maintain for a year. Whilethe cost of planting is not so serious and can be reduced by growing the young treeson the farm, the cost of growing timber strips of thousands of trees is impracticableunless some cheaper and easier methods are devised. Keyline planning and developmentmay permit the closing of paddocks from stock for three or more years while cropsare grown. This amount of time will allow a planted or "induced" timberbelt to develop to a stage where the trees will survive without attention.
In large or small paddocks without trees that are to be Keylineimproved a timber strip five to ten tree-rows wide can be planned. After the paddockhas been completely cultivated tree rows are marked, the first row by a deep singlerip cultivation parallel to the Keyline or a guideline. The distances apart of thefurther rows of trees are gauged by the tractor that will later cultivate betweenthese rows. The following procedure has produced good results:
After completing the full Keyline cultivation of the paddock,mark out by a single rip the first tree row position. A single shank is allowed topenetrate deeply through the plowed soil. On the return run with the tractor placethe uphill side rear wheel in the lower wheel track of the first run and travel thetractor back without ripping. Turn around and again with the uphill side rear wheelin the lower track of the last run mark out by ripping deeply the second tree row.Repeat to the number of tree rows to be planted. This row spacing will allow thetractor later to cultivate satisfactorily between the tree rows and one or two cultivationsare done during the first year after planting the young trees.
The preparatory cultivation takes place some months prior tothe time for planting the young trees so as to collect, in the drier conditions,as much deep moisture into the earth as possible. The object is to improve the soiland to provide sufficient moisture in the soil before the planting of the young treesand so avoid entirely the necessity for watering later. A delay in planting for ayear while the soil improves from a cultivation after each rain will be quickly offsetby the faster growth of the trees.
Australian native trees should be planted when a few incheshigh and a few months old and planted directly from the tubes as used by the ForestryNurseries. Plant the young trees well into the moisture zone without breaking thetubed soil in which the tree was raised. Press the soil firmly around the young trees.Trees can be planted very quickly into this deep moist soil with very few lossesand without the addition of any water. The distance apart of the trees in the rowmay be closer than is intended for the developed trees. Spacings of eight feet aresuitable for a variety of tree species. Planting time varies in different districts.
If watering and hand cultivation can be avoided, the chief costof growing the trees is also avoided.
A tree strip may sometimes be satisfactorily grown by plantingthe tree seeds directly into the paddock.
Trees can be induced to grow by a variety of means without theactual planting of young trees or tree seeds by merely leaving a strip of unplowedcountry when the paddock is closed for cropping. Tree growth will often flourishon this strip and form a valuable tree belt.
Two interesting incidents of my own experience will serve toillustrate possible low cost means of growing valuable timber strips.
During the construction in 1944 of several water conservationdrains all except one were harrowed and fertilised. A directive was given that thisone drain was not to be treated or touched in any way in order to see just what wouldgrow on it. A variety of vegetation rubbish grew quickly on this exposed subsoil.Three years later a row of trees twenty feet high and all of one species coveredthe drain.
In the drought of 1944 several runs with a heavy road plow weremade to form a fire break. Later the dry grass of this fire-break strip was burnedoff. The paddock was not stocked heavily during the following two or three years.At the end of this time the fire-break strip alone was then well overgrown with trees,all of the one species. The trees here were a different species entirely from thosewhich were growing in the drain less than a mile away.
From these events it can be seen that whenever a treeless paddockis to be closed up for cropping for two years or more a suitable marked and plannedstrip of land could be left untouched, or perhaps given some special attention, soas to allow a timber strip to develop of its own accord. Once the trees are threeor four years old the majority will survive stock damage.
There is still another aspect of treed land and cleared land,and that is the bush fire and grass fire hazard. In Keyline this hazard is negligiblefor the following reasons : With farm roads in the right places for quick access,the tree belts widely spaced, the grass paddock rotationally grazed, and water atintervals to be distributed crosswise for long distances through the farm, a fireoriginating outside the property could not make headway.
The relation of tree belts to cleared strips and to soil andpasture development is well illustrated in many of the plates in the pictorial sectionat the end of this book.