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IT has been previously stated that Keyline cultivation parallels fromthe Keyline up the slope of the land and from the Keyline down the slope of the land.However, there are very many properties that do not contain Keylines or a singleKeyline, and so a means of the simple application of Keyline cultivation on suchlands needs a Guideline on which to work.
These areas or farms are treated in the same way as are all areasbelow the Keyline. Cultivate the land parallel to the highest suitable Guideline,always working parallel down the slope of the land.
The line that forms the overall or planning guide on these propertiesis called a General Guideline, and, as with the Keylines, may be either a selectedtrue contour line or a line with a very gentle slope. The slope would be for thepurpose of a water race connected to a water storage.
The special or significant feature of all land lying below the Keylinesis that the valley slopes are generally flatter and wider than the adjacent ridgeslopes that form the valleys. This was fully explained in Chapter 2. The aim of Keylinecultivation is the equalising of the moisture between the wettest and the driestparts, that is between the valley and the adjacent ridges. To do this most effectivelya Guideline is located in the highest position, where it can serve as a guide forKeyline cultivation.
If the slope is long, another Guideline at a lower level is located.It lies at a convenient distance below to serve as a boundary to the upper area.This is a Lower Guideline and it is usually a true contour line. It is marked byany suitable means, preferably one that permanently locates it.
The control and development of these areas is approached first froma consideration of water which flows down to the valleys from the higher countryoutside. The entry of this run-off water is usually at the lowest point along thehighest boundary fence. This may also locate the Guidepoint from which a level orsloping line in both directions suitably forms the General Guideline.
If a large area of land lies above the selected General Guidelineit will be necessary to locate an upper Guideline to control the Keyline improvementof the higher area. If so, the upper Guideline is located and marked as high in thearea above the General Guideline as possible. Care should be taken to see that itis of sufficient length to serve its purpose.
Outside run-off water may now be a problem. Perhaps the main factorin determining the General Guideline will be the position of a suitable conservationdam site for the storage of this extremely valuable water. This site is looked forin the highest third of the area, and when located the General Guideline becomesa suitable water race to the dam site.
All the details of farm planning above the Keyline also apply abovethe General Guideline of the land below the Keyline.
The main grazing or large cultivation area is below the General Guideline.A Lower Guideline located at a suitable distance below forms the top boundary ofanother group of smaller paddocks. If their vertical distance below the conservedwater is sufficient, gravity spray irrigation is always planned. Five per cent. ofa grazing property that is suitably planned and supplied with water for gravity sprayirrigation may add fifty per cent. or much more to the capital value of the wholeproperty.
In the development of timbered areas of this type of country, clearingis done to leave suitable timber strips along the General Guideline and all Guidelines.
The formula mentioned in Chapter 8, which relates the vertical distanceapart of these tree strips to the general height of the trees, is again the planningguide.
Map 6 illustrates in simple form a valley area below the Keyline andthe location of the Guidepoint and General Guideline. The parallel lines on the mapwhich start from the General Guideline and parallel it downward illustrate the driftof water out of the valley. This compensates the natural water concentration in thevalley. Keyline cultivation is again completely effective.
In selecting the Guidepoint--in place of the Keypoint of propertiescontaining their own Keyline--it may be advisable to locate it just away from thefence at the lowest point along the highest boundary. A distance of 20 feet fromthe fence would allow a farm road to cross the paddock above the General Guideline.
Soil erosion by water is simply and profitably cured on flatter landsby the methods of this book.
There is, however, a type of erosion that appears to defy man's effortsto cure it when these efforts are confined to "maximum soil improvement".This is the serious periodic erosion by wind, which occurs alike on poor soils andfertile soils of our marginal lands.
Following a period of three or four years of much drier than usualconditions on this country when it has a normally sparse rainfall, this serious winderosion manifests itself. If the latter end of a dry period coincides with that ofa severe drought, followed by high wind, these soils will move in vast quantities.
The dry period or the severe drought cannot be controlled and theonly possible solution to this problem lies in measures designed to retard the groundvelocity of the winds. A rough cloddy surface will reduce a 60 m.p.h. wind to a velocitythat will not raise any appreciable dust from this soil, but at the end of such aperiod of weather conditions as described the surface condition alone will not havesufficient effect.
The growing of sufficient tree strips is the only possible means ofreducing the high velocity of these winds to such an extent that the soil will notblow. The problem is one of great magnitude and the solution in the planting of treesmust be of like proportions.
Indigenous trees can be induced to grow by leaving protected stripsof land in the right pattern. This is the lowest cost means of growing the tree stripson a large scale. If the country is treeless, then tree species will have to be introducedwhich will not only grow well in this country but survive the period of very dryconditions.
Nothing can be done during the time of the actual blows that willgive results commensurate with the money expended. The planning of the work can besatisfactorily done at this time so that when better rainfall conditions follow thedrought the land will be in a position to make quick rejuvenation. Four years laterthis land could be safe from wind, erosion.