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   THIS chapter will discuss how water conservation drains are designed and used to fill the keyline dam described in Chapter XVIII. This project is now to be completed to the stage of watering and the managing of irrigation land.

   The line of the water conservation drain may have been pegged prior to the construction of the dam during the marking out or site preparation. The keyline dam water conservation drain starts from water level at the overflow point of the spillway, which is on the line of the centre of the wall. Preferably a line is pegged rising at 0.5% right round the dam in the direction of the general rise of the country. (N.B. The spillway is usually on the downland side of a keyline dam.) Where the land shape has smooth contours, pegs 50 feet apart may be suitable for the construction of a drain, but it is preferable that Pegs be placed at closer intervals around the inside bends of valleys or the outside curves of ridges. When a peg intermediate between two 50-feet pegs is to be placed, it is not necessary to level in the peg 1-1/2-inch fall in 25 feet. The intermediate peg can take its height from the last preceding level.

   The section of a water conservation drain provides that the centre line of the drain bank is over the pegs. The pegs, when placed, represent the centre line of the embankment of the drain, so that when digging commences in the construction of the drain, earth is moved from a line some feet above the pegs, so that the centre line of the finished bank will coincide with the pegs.

   Various implements can be used for the construction of the drain, from 3-point linkage attached-farm-graders through to the angle-blade large bulldozer. If a farm implement is to be used, a chisel plow should first cultivate the area above and below the pegs, and by just missing the line of pegs and leave them undisturbed. From two to four runs of the plow may be necessary, according to the size of the drain. The plowing of the land below the pegs assists the bonding of the subsequent bank material.

   A single deep rip furrow made with a small tractor, travelling so that the downhill wheels leave the pegs undisturbed, is a further aid to the construction of the drain with the smaller type of equipment. The farm grader can then be operated, digging the earth from a regular distance above the pegs and throwing it towards the pegs; in this way half a dozen or more runs may be necessary to form the drain, including its bank. Throughout the operation the pegs should be preserved in their true position. Pegs are preferably about two feet high.

   The size of the drain depends on the slope of the country and the amount of catchment area above the drain. The conservation drain section illustrated is the one I generally employ for our own keyline dams. Its capacity range is upward of 350,000 gallons per hour. (See Fig. 13, Chapter XVIII ).

   There is a tendency for all equipment to "pull down" on the inside curve when the implement is travelling around a valley, and to do the opposite, i.e., climb-up when the implement travels on the outside curve around a hill or ridge. It is convenient and good practice to put in marker pegs one foot to three feet above the line-pegs in the valleys to compensate for this tendency to pull down. After the first couple of runs with the implement the obvious corrections can be made. Similarly, but in a reverse manner, compensation is provided against the tendency of equipment to climb on the outside curve of a ridge.

   An angling bulldozer (angle 'dozer) provides a very efficient implement for constructing water conservation drains. The angle 'dozer should be operated with the heel of the blade against the lower or downhill track of the tractor, and working in such a manner that the lower track is in the cut of the drain as it is formed and the uphill track above the cut. The pushing forward and sideways of the earth with the angle blade tends then to throw the rear of the tractor uphill, but the weight of the tractor compensates for this and permits highspeed accurate drain construction. Again, some allowances must be made for a tendency to move downhill on the inside curve around a valley and to move uphill on the outside curve round a hill or a ridge. The line of the cut of the drain is again uphill from the line of pegs, the first pass being made in such a manner that the earth from the blade falls on the uphill side of the peg.

   The angle 'dozer operating this way works like a giant mouldboard and can be operated efficiently by maintaining as big a bite as the tractor will cut and push evenly in second gear. It is advisable for a man to walk ahead of the tractor with a 6-foot pole, which he holds on the line peg and ahead of the 'dozer, so that the operator can see his line of travel clearly. The operator on his own cannot sight the pegs of the line quickly enough to maintain the generally smooth even curves that are desirable in these drains.

   After the first run the full length of the drain, the tractor makes another pass. The tilt of the angle blade needs to be readjusted, so that it cuts a drain to its pre-determined shape. Two rapid passes will often shift sufficient earth to form the drain illustrated by the section diagram, but in harder conditions three or four passes may be necessary. Feeder drain sections, notably the shorter-length drains (under 900 feet), when newly constructed, are a flat V section with the uphill line and the bottom point of the V represented by the cut of the angle blade and the downhill shape of the V represented by the slope from the deep point of the drain to the centre line of the earth bank and the pegged line.

   For longer drains with larger capacities, their section is represented by a flat centre section of the drain equal to the width of a 'dozer blade, a long sloping uphill cut on the topside, a long slope to the centre or high point of the bank on the downhill side to the pegged line, and a further earth slope behind the bank. Where the length of a feeder drain exceeds 900 feet, it requires theoretically a progressively larger section of drain to carry the quantity of water which in effect increases throughout its length from its beginning through to the dam. This can be achieved by constructing the drain from the end near the dam, and after completing the necessary number of runs to form the drain to the section required at the end away from the dam, make two more runs from the dam-the first one travelling three-quarters of the distance of the drain and the last run half the distance of the drain from the dam end. This provides a larger section of drain where the water flow will be greater. One extra run in a drain considerably increases its carrying capacity. (See Pictorial Section.)

   Water carrying capacity, increasing as the length of the drain increases, may also be affected by planning the feeder drain with increasing rates of fall towards the dam. A steeper rate of fall is therefore to be made in the section near the dam and the flatter fall in the end section furthest from the dam. However, the drain of uniform fall, but increasing in size, if necessary, as it approaches the dam, is the type preferred.

   The angle 'dozer constructed drain, while being the cheapest and fastest method I have employed, leaves the bank somewhat lumpy and uneven. Farm equipment can then finish off the drain quite smoothly. The upper wheel of a farm wheel-tractor with an attached chisel plow is placed in the bottom of the drain with the downhill wheel on the drain bank. One light run with the implement will smooth off the shape of the bank. A farm tractor and attached grader can also be used to trim up both the inside and outside of the drain bank.

   As soon as the water conservation drain is completed, the hard, newly-cut surfaces should be cultivated to a depth of 2-1/2 inches or three inches with the tractor and implement and working on its first run with the downhill tractor wheel in the bottom of the drain and its upper wheel higher on the cut section of the drain. The whole area of the drain is cultivated once and parallel with the drain. The drain should be immediately sown down to the usual pasture mixture, together with an application of fertiliser.

   It is desirable in the interests of the efficiency of the drain and the working of the property to have the pasture in the drain area of as good or better quality than the rest of the paddock, so that stock will keep this area eaten off. To this end, it may be as well to double the application rate of superphosphate on the soil of the drain area which, after all, by virtue of the topsoil being removed, may be very poor.

   The feeder drain is designed as above, commencing from the ccntre of the spillway at the centre line of the wall, so that complete control over water can be exercised at all times. For instance, with the drain starting from this point and rising steadily right around the water line of the dam, the drain is above the end of the wall at the opposite end from its starting point. There is no interference with the wall. With the drain in this position, water can be let into the dam from any part of it around the dam. If there is an eroded area within the top water line of the dam, run-off water can be flowed into the dam over another area, avoiding the eroded area altogether. In order to by-pass water over the safe area into the dam it is only necessary to block the drain at the desired place and trim its bank for a short distance.

   If required, run-off water can be by-passed right around the dam into the spillway and on to the water conservation drain or catchment area of another dam. If the overall plan envisages the maximum possible conservation of all run-off water no other design which embodies a different association of the feeder drain and dam to this layout will serve as efficiently or be as satisfactory.

   A feeder drain should never be constructed to discharge water directly into the dam near the wall, although this has been the procedure on the farm dams where feeder drains are used other than those of our own design.

   In Keyline there are usually only two drains down the land slope, one being the feeder or water conservation drain now discussed, and the other the irrigation drain. Heavy run-off water can pass over an irrigation drain without damage, so that there is no vital necessity that a feeder drain be constructed to such size and in such a manner that it never fails to hold and transport all the water that runs into it. If a feeder drain is sufficient for its purpose of filling the dam, but not large enough to transport the largest flood rains, then it is desirable that the area where water will overtop the drain should be deliberately located. A slightly lower bank produced by levelling off by hand on a suitable ridge section which has been Keyline pattern-cultivated provides a perfect safety against the heavy flood rain. The maximum amount of control should always be exercised over water on the farm.

   Marking Irrigation Drain: The purpose of the irrigation drain is to transport water from the outlet valve along the higher boundary of an irrigation area. Marking out or levelling in with a level should commence at the valve.

   A fall or grade similar to that employed for the feeder drain is suitable where the land is not too flat. In our own irrigation drains we generally provide a steeper fall (up to 1% grade) for the first 50 feet of drain from the lockpipe in order to counter an occasional tendency for a wet area to form near the outlet.

   A high degree of accuracy in the construction of a feeder drain is desirable, so intermediate levelling pegs as close as 12 feet 6 inches or less apart may be placed to preserve the generally even-curved line of the drain.

   On even-shaped land this procedure imparts perfect curved shapes to the drain and preserves a very desirable accuracy of line in the finished drain. As water is to flow over the edge of the irrigation drain for distances of up to 50 feet, some effort should be made to get considerable accuracy in the layout of an irrigation drain.

   Constructing Irrigation Drain: The irrigation drain serves a totally different purpose to the feeder drain, and it is of different design and construction. It is designed (in undulating country) so that water flows within the excavated drain entirely, and no assistance being provided by a bank formed from the excavated material, as in the feeder drain. (In flatter country the design may be different.)

   The irrigation drain is constructed with the lower edge of the excavated drain on the line of the levelled marker pegs, so that the water it transports, on being blocked in the drain with the blocks, spills over solid unexcavated material. Preferably the drain should be constructed with the excavated material thrown uphill to be spread out there, but in practice there is no farm equipment that will do this operation properly. On land with any slope, earth does not throw uphill readily, and the construction of an irrigation drain inevitably requires some hand work. (See Fig. 13, Chapter XVIII.)

   There is no suitable implement that will construct an irrigation drain to the desired sections in country of different slopes. An implement could be made that would be suitable for certain slopes of land, but its range of uses would probably be very limited. However, it is suggested that the drain be constructed with the use of one or more implements such as a delver, ridger, lister, or even a large single furrow plow. The first run with a farm tractor and any of the above implements should be made in such a way that the ground broken by the implement should not extend downhill to the pegs. Some implements will throw a measure of earth uphill, but there will always be a spill of earth onto the lower side of the drain which, if only a small amount, can be levelled off there by spreading, or preferably thrown uphill to the top side of the drain by hand shovel work.

   The implement used should break the ground above the pegs and within the finished section size of the drain. When the soil is broken to the desired depth and a little under the finished width, the drain can best be finished by hand shovel operation by spreading the loose earth uphill and preserving the exact width and depth of the drain throughout and working in such a way that the pegs are still in position and an inch or two from the lower edge of the drain when this is completed. As soon as the drain is completed a small quantity of water should be let into it from the outlet valve of the dam to check the drain. The final finishing can then be done very accurately. Another larger flow of water could then be turned on for a short time as a final check.

   Irrigation: When irrigating from the dam and employing Keyline flow methods, the water is first turned on at the outlet valve and allowed to flow to the end of the drain on the downland limit of the irrigation area. A block made of sheet metal or earth or any other suitable material is placed in the drain at this point, and by blocking the water, ponds it back and forces it to spill over the lower lip of the drain and run down over the land.

   (NOTE: After irrigating, the drain stops are placed at intervals along the drain, so as to distribute any run-off rainfall.)

   In order to preserve the correct water spread, proper time of complete wetting and for continuous soil and pasture improvement of the paddock we have employed certain specified procedures.

   Pattern Plowing of Areas: The even spread of water is obtained by the pattern impressed on the land by the design of the appropriate keyline cultivation.

   Keyline cultivation is simply cultivation with a chisel plow which parallels a selected contour line in such a way that when the parallel cultivation inevitably moves off the contour, the furrows oppose the natural flow pattern of the run-off water. The irrigation water then spreads evenly over the surface. The main art in keyline cultivation, when it is used in this manner as a positive control for the spread of irrigation water, lies in an understanding of the actual contour shape of the irrigation area, and in being able to select the line which is to guide the parallel cultivation, and then to determine the correct paralleling of this line, whether above or below it.

   While this is simple enough in its cause and effect, it is not always at the outset fully understood to the extent that an inexperienced landman can put it into operation effectively on his own without first studying the land shape. He can, however, by the following procedure, illustrate the contour shape of the area and so determine the methods which will control the irrigation water effectively. The contour shape of an irrigation paddock can be determined and transferred to paper in the following manner: First, a line is drawn on a sheet of paper representing the approximate curve of the irrigation drain. Next, in the paddock, step a distance from the centre point of the irrigation drain and downhill at right angles from it about 90 feet and place a peg. From this peg run a true contour line in both directions with a levelling instrument, placing pegs at 50-feet intervals across the irrigation area. Next, place another peg 90 feet downhill at right angles to this contour line and peg another contour in the same manner as before. Measure and mark on the paper the distance of the two contour lines below the irrigation drain, marking first the distance stepped or measured at right angles from the irrigation drain to the two contour lines below. Then about three distances from the irrigation drain to the first and second contour line and each side of the centre are measured and marked in on the paper. These measurements are taken from even distances along the drain line (at right angles to the drain) to the first contour; and again at right angles to the first contour down to the second contour and marked in on the sketch. The contour shape of the area is disclosed by joining the points to form the two contours below the drain, and the appropriate guide for the cultivation can be selected.

   The irrigation area watered from the dam should quickly become of high productive value, so it should be suitably fenced. If the area is already carrying a good pasture, it would be as well to feed it off quickly, and then, if the weather is dry and the land likewise, cultivate to the particular pattern which was selected.

   Cultivation Procedure: The cultivation depth should be carefully determined beforehand by the following means: The soil is examined with a spade to determine the depth where, by the appearance and smell, the soil could be considered to be in reasonable condition, namely, fertile. It may be only one inch deep and will rarely be more than 2-1/2 inches. If it is the minimum of one inch and the pasture is fairly tight, a cultivation should not be more than two inches deep. Such cultivation need not disturb much of the pasture.

   The first watering of a new area is preferably given in the morning, so that, with the mistakes and delays that may occur, the irrigating can be at least completed on the day it is started. In watering, certain relevant details have to be determined, and, first of all, is the width of the strip of land below the irrigation drain. This width should be narrow enough to enable a full flow of water from each overflow position on the drain to extend across 90% of the distance within a period of one hour. The reason is simply that land thoroughly immersed or saturated in water for any period of time longer than one hour may suffer "drowning". The beneficial soil life, which, after all, produces the various factors which we call fertility in soil, require oxygen. The whole complex of this life can be seriously disturbed and changed if water is continuously left too long flowing over land. The ideal length of time is somewhat less than one hour.

   Irrigation is designed to produce abundant pastures or crops in the best seasons as well as the worst of seasons, and this is the basis or the reason for its use. However, fertile soil will produce more under irrigation conditions than infertile soil, and it is a deliberate function of irrigation to control water and air in relation to warmth in such a way that the fertility of any soil, fertile or otherwise, is rapidly increased. An inch of fertile soil under controlled irrigation conditions as in Keyline, can be converted into a foot or more of depth in two seasons of irrigation. This depth and degree of fertility can not only be maintained but increased.

   Irrigation of the new area is accomplished in the following manner. The valve at the dam is opened and the water is allowed to flow to the far end of the irrigation drain. Here the first drain block has been placed. The drain block or dam may be a piece of sheet metal cut to the shape of the drain and pushed into the earth. A few shovelfuls of soil on the water side of the block may be necessary in order to make the block effective. The water thus held back overflows the lower lip of the drain and spreads down the slope of the irrigation paddock. Before the foremost edge of the flowing water reaches the lower limit of the paddock a second drain block is placed to spill the water again at a new site fifty to one hundred and fifty feet away and towards the dam. The distance from the first block to the second may be gauged approximately as 2-1/2 times the distance to which the water of the first block has spread laterally from the overflow position. Irrigation continues until the end of the area nearest the dam is watered and the watering is completed.

   The first irrigation of a new area should provide the information for future watering procedures. The length of time that it takes flow water to reach the lower side of the irrigation paddock is determined and it should be less than one hour. Later irrigation of the area would simply mean that the farmer controlling the watering would come back to the area every half to one hour period, according to this time of flow, and with experience after a few waterings it is a simple matter for one man to control three or four dams contained in an area of, say, 600 acres.

   On good, even-shaped land we have found that the first watering generally produces a good distribution, but on occasions there will be small areas unirrigated. The paddock should be examined twenty-four hours after watering to determine the effectiveness of the spread, and unless sizeable areas have been missed, it would be unnecessary to especially irrigate a dry area. Thirty-six hours after watering the condition of the land should be such that all is moist but none is wet and none is dry. Dry spots should be marked and studied in relation to drain block positions, so that on the following watering more effective spread would be secured.

   Not all land takes water in the same way, because the shapes all differ, even a little, and the shape of the land and the cultivation pattern are the controlling factors. A good spread of water does not at first occur where the land is without a sufficiently uniform contour shape. Small local depressions or rises that are unrelated to the general shape of the land can cause too much moisture in the hollows and too little moisture on the rises. A corrected plowing pattern determined on inspection may be the suitable answer. On other occasions, the nonuniform areas may be too small in size to enable a plowing change to be implemented, since the distance of movement and change of movement in the plowing may be too short to be practical. In this case, "border checks" can be used to direct water to the awkward spot.

   Border checks are one of the means of controlling water in flatter-land, flood-irrigation systems usually associated with the large irrigation areas. Generally with this method water is carried along the higher border of the irrigation country, which may be very flat, and water flows from the irrigation drain through various outlets along the length of the drain. The uniform spread of the water over the country is controlled by the border checks, which are small banks of earth 18 to 24 inches wide by as little as three inches high, which are thrown up by a "crowder" at right angles to the drain. The border checks parallel each other down the slight slope of the land at intervals of about 30 feet and provide an efficient means of spreading water uniformly over the land. It is sometimes called border strip irrigation. This check or bank is used where necessary in Keyline pattern irrigation to take water to the unwatered area, but whereas in conventional border check or border bank or strip irrigation numerous border checks are used, one to three banks is all that is likely on a reasonably-sized irrigation paddock in Keyline pattern irrigation. However, a study of the pattern of water movement and of areas not watered 24 hours after watering ceases will indicate quite clearly whether one or two border checks will assist the even distribution of water.

   "Crowders" are the regular implements used for constructing border checks and consist essentially of two blades six feet long similar to those on small graders. They are arranged in an open V with the forward ends of the blades six feet apart and the rear end of the two blades around about two feet apart. The blades have various means of control, and, by travelling forward over land that has been lightly cultivated, in one run crowd sufficient material from the wide open end of the blades to the narrower end to form a satisfactory small bank without leaving a notable depression in the areas from whence the soil is taken. The same effect can be achieved quite satisfactorily in two runs with a small farm grader.

   Distance of Water Flow in Irrigation: In considering the distance of water flow, it must be realised that soil will change by developing improved fertility and structure under good irrigation conditions and will be changed by deterioration if the soil is not managed properly during increased water application. Clay soils may allow water to flow at the first irrigation a relatively long distance rapidly. With the improvement in soil fertility due to well-managed irrigation, the distance water will flow then may be considerably reduced.

   Soils that are poor and porous, such as some low-quality loams or sandstone soils and some granitic soils, will, by seepage, limit the distance of water flow in the hour, but with rapid fertility improvement the distance will increase. Where circumstances permit, it is preferable that the water for the irrigation area be supplied by the one drain, and that the distance downhill across the irrigation area be limited to a distance that water will travel within an hour, and at the same time provide a strip of unirrigated land below the irrigation paddock, and at least as wide as the irrigation country itself. This strip lies between the irrigation area and the valley below. For instance, if a dam provides sufficient water for the full irrigation of ten acres of land, it is preferable that the shape of the land be rectangular along the irrigation drain; 14 chains long by 7 chains wide, instead of square, 10 chains by 10 chains.

   Where, by the shape of the land, such arrangement is not possible and a square block has to be irrigated, then watering could be by two drains, one at the top of the irrigation paddock and one across the centre, both falling in the same direction at the same rate of fall. The irrigation procedure then would be to commence at the end of the top drain away from the dam and watering the top strip progressively back towards the dam, and then by flowing the water over a specially prepared path, as between two border checks, allow the whole of the water to run into the second drain and complete this area by watering from the end of this drain away from the dam, and proceeding, as usual, back towards the dam.

   Management of the Soil in Irrigation Land: The treatment that a soil may need varies widely according to the present state of development of the soil and to weather conditions. There is no exact theoretical method of determining the water requirements of a particular soil that will equal the practical examination of soils on the spot by the farmer with a spade. Many factors affect the development and fertility of the soil, but probably the overpowering influence is that of soil climate. The aim is always to provide the best condition of moisture, warmth and air in the soil for soil life and plant growth.

   An examination by the farmer of the soil in an irrigation paddock is made by digging a spit of soil with a spade to the full depth where any pasture root penetrates.

   Examination takes place by the look and feel of the soil to determine whether it is friable and crumbly with the unmistakable appearance of fertile soil. The fertility or otherwise is checked by the smell of the soil. Almost everyone, even without experience, knows the typical delightful smell of fertile soil. Below the zone of fertility determined on these lines, which may be only an inch or two, the soil will appear either close and compacted in clay soils, or loose, clean and sandy in light soils. The top zone of compacted soils is apparent to the eye and feel, and usually has no smell whatsoever. It could be called the neutral zone. Below this zone, there will be a change in the soil again, obvious both through sight and feel, and there may be on occasions a very definite change of smell to sour and perhaps objectionable.

   The best means of improving soil is the right type of cultivation at the right time. Cultivation with a chisel plow and on the pattern decided for the irrigation area, should be undertaken when, from this examination, the soil needs it. The soil of the irrigation area should be closer to its drier condition than to a good moist condition. Cultivation can be best undertaken immediately stock has moved off the area. In warm weather irrigation is done on the following day. Cultivation time and depth should always be decided strictly on the condition of the soil at the time. Penetration that is too shallow will usually do some good, but a depth of penetration that is much too deep provides only the minimum benefit from the maximum water application. The penetration should just exceed the main pasture root zone and enter the neutral zone of the soil. With a soil in dryish condition, the resultant cracking coupled with the correct depth of penetration provides the air requirements and the space for the continued development of the soil without waste of water. With experience, cultivation can be used to control very precisely the amount of irrigation water taken in by the soil.

   The response of the pasture and the soil to this planned procedure will be that the major root zone will deepen and at the same time, where warmth conditions are suitable, a rapid development or even a climax of development of soil life takes place by the provision of well nigh perfect living conditions for that life. These good living conditions, extending, as they do, just through the maximum root zone, allow the soil life to develop rapidly from the abundance of its food, the best food of all, the dead roots of pastures.

   The improved conditions in the soil, both for soil life and pasture growth, continued for a period of only a few weeks, will, on examination again by the farmer with his spade, disclose that a rapid development of the depth and quality of fertility has taken place.

   On clay or heavy soils resulting from the break-down of mudstones, slates, schists, etc., experiments in the cultivation of irrigation land have been conducted on our own properties six times during the warm and hot weather, with a resultant continuous improvement in soil development and pasture growth.

   It is not known how many cultivations a pasture in this type of soil, coupled with good irrigation, will stand during, say, the hottest seven months of the year before the cultivations end in a detrimental way by destroying too many pasture plants, or in other ways by restricting soil development. Obviously, there is a stage where too much tillage would be damaging, even under the best irrigation procedures.

   It is suggested that. the pasture soil be examined by inspection with a spade every month during the first year of irrigation, and that cultivation during this first year be as frequent as is indicated by the condition of the soil.

   Of the two types of soil, heavy and light, the depth of cultivation is somewhat more critical in the light sandy soil, and, as a general rule, the cultivation depth of these soils should only be allowed to penetrate just enough through the major root zone. The factors of cultivation are again more critical during the first year of irrigation. During the second year, the irrigated land will be totally different from the original soil. It will then hold a condition of better balance than previously of the factors of moisture, warmth and air. It will require less treatment for its continued development. Earthworms will have come in, whether they were previously apparent or not. The earthworm life should develop rapidly and probably by the end of the second year of irrigation the depth of fertility and the structure of the soil may be such that it will look after itself, continuing its further development automatically.

   While it is quite certain that this rapid soil development with its consequent beneficial effect on pasture and stock does take place in this manner in a short time, it is not certain yet how long the fertilty developed in a year or two will continue to improve without further work (keyline cultivation) or whether or when this process will stop and a decline set in.

   On "Nevallan", our experiment farm at North Richmond, we had country of very varied earth types. In one part it ranged from the shallowest grey soil through to yellow clay subsoil; others from yellow subsoil to soft yellow shales, even to medium hard blue shale, and all to be seen on the surface. There were other areas of sandy soil, with places where the sand was dean enough, and we used it in cement work for our buildings. On all these earths and under natural rainfall conditions, eight inches of highly fertile soil had developed in three years of Keyline treatment. During the next two years, the depth of this fertile soil had increased to two feet, with the roots of the pasture grasses well in evidence at that depth. Some green growth was continuous through the recent drought, the worst since 1944. A dramatic soil development during the fourth and fifth years had taken place naturally from the fertility that had been developed through the first three years of Keyline work.

   How long this process, which increases the fertility and extends the depth of the fertile soil, will continue is not known. The ability of the developed soil to look after itself has been shown by the fact that it was apparently unaffected by the long-term saturation of the soil which extended from early in 1956 right through to the winter months, and by the fact that during the drought referred to it was able to maintain a green growth of grass where no other neighbouring rain pasture could. The earthworm population, which became apparent for the first time in March, 1954, has developed rapidly in numbers and size. Earthworms larger than those ever seen in the district can be obtained in every shovelful of earth during the casting seasons for earthworms when the moisture conditions are suitable.

   These facts indicate that the state of the soil should be watched continuously even after the second year of irrigation, and if there is any falling away of condition, as evidenced by compaction, loss of structure, or the absence of a noticeable increase in the earthworm population over the previous year, or evidence that the neutral zone (zone of no smell) is higher, then keyline cultivation should again be introduced.

   Cultivation of the soil in its condition after two years of development by irrigation and keyline cultivation will be a different matter to the cultivation of the first year. It will now be practically impossible to cultivate too deeply, because of the depth of the developed soil. From then on the soil can be worked, when cultivation is needed, to as deep as the logical maximum that is suitable to the chisel plow and the particular farm tractor, with, however, the effect kept in mind that it will have on irrigation water.

   Experiments have shown that as progressively deeper cultivation is followed in the first year of irrigation, the improved structure and fertility of the soil develops beyond the depth of the work. It is therefore not necessary for cultivation towards the end of the second year to reach the full depth of the new soil.

   The recompaction of a fertile soil that has been developed by these methods if and when it does take place, affects only a limited depth from the surface. Compaction does not seem to take place below five inches. A cultivation maximum depth of five or six inches may be all that is necessary to treat quite effectively a depth of 24 inches of developed soil.

   Sowing Seed into Irrigation Areas: On occasions it may become advisable or desirable to introduce new species of grasses into an irrigation area. Sowing should be done as accurately as possible and the condition of the ground is preferably just moist or even slightly drier than would be considered good sowing conditions. The area may then be watered immediately and closed up for about two weeks before stock are brought in.

   The reader having come so far will appreciate that the methods and procedures discussed above are not those now in general application for the management of irrigation pasture. Official recommendations do not cover the Keyline cultivation pattern as a control for water distribution. Continuous year-by-year applications of artificial fertilisers, and particularly on irrigated pasture, is the usual orthodox view. It is quite clear that the controlled application of water, plus artificial fertilisers, plus lime on occasions, will produce lush and abundant pasture growth with high carrying capacities. The assumption, which I do not accept, is that the important factor is to keep the top inch of the soil in a good pasture-growing moisture condition and replace the loss of nutrients from this thin band of soil by regular applications of the appropriate artificial fertiliser. It is assumed that, in general, phosphates are deficient in soils and need to be replaced by regular applications of superphosphate. Continuous application of water under these conditions induces soil deficiencies of other mineral elements of fertility, which have then to be added artificially on appropriate occasions.

   The Keyline methods, however, assume generally that there are adequate minerals of all varieties present in the soil, but not necessarily in available forms or states, and it is good practice to make the unavailable minerals (phosphates generally being the critical one) available immediately by an appropriate application of superphosphate at the start of the development of the soil of an irrigation area. However, the rapid climax development of soil life due to the improved condition of the soil climate act on the existing but unavailable minerals and breaks them down rapidly into forms readily available to plant life. Chemicals, such as superphosphate, are, with advantage, used once or twice in the initial stages of soil development. Their purpose in Keyline is to provide rapid development of pasture root growth as well as pasture, so that -a basic food of soil life, dead roots of grasses, is in abundant supply as soon as possible. The continuous development of soil by the maintenance of the best possible soil climate right through to the depth of the zone of maximum root development during the first two seasons, continuously and progressively makes available the mineral elements of fertility and processed to their most perfect form by the natural factors operating on them. The effect is that in irrigation in Keyline the pasture is soon produced from some feet depth of fertile soil instead of from an inch or two of a very artificial growth medium.

   I have proved, to my own satisfaction, that this conception of soil and pasture development, now commended to others, is a satisfactory and practical one.