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Mallee - Part 2
Image 171
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these samples were taken in July when the rainfall may be supposed to have washed some of the salt to the lower depths of soil as shown. The first eight samples were from cultivated lands; the last two are not stated, but in view of the fact that three depths were taken of the soil the lands were probably considered suitable for agriculture. Of these 10 samples I should say that— 3 were safe, 2 were doubtful, 5 contained too much salt. The above figures of analyses include all from which we may safely form conclusions among the analyses of 1912. Earlier figures of minor value. Table 10 as above shows analyses of Esperance soils samples to 36 inches in July, 1912. The 1912 Report also gives the analyses of a large number of soils sampled earlier in that year (January-May), but many of those taken to nine inches only, and the remainder to 18 inches only. It is impossible to draw definite conclusions from such figures, more particularly as regards any absence of salt. They have, however, a limited value in a general sense, and the figures of such soils as were sampled to 18 inches are given in Table 5 (Appendix A) of this report. The soils there included are dotted all over the area lying between the 80-Mile post and the southern fringe of the Mallee Belt (about 25-mile post). Thirty-eight soils included in the table, and, making allowance for the probably greater content of salt which would exist in the third foot (compare Table 4, Sec. 2, App. A), I should place these 38 soils as :— 11 Good, 13 Doubtful, 14 Bad. This estimate, however, is made with reserve for the reasons stated. Salinity varies from place to place. Enough has been said to indicate that the Esperance district is neither all too salt nor is it all free from too much salt. As a fact large areas are undoubtedly charged with too much of it. For information on this point we have 16 soils fully examined in 1917 down to 36 inches, 10 soils examined for common salt only in 1912 down to 36 inches, and 38 soils examined in 1912 down to 18 inches. The results may be summarised thus:— TABLE 11. Relative proportion of safe and unsafe soils. Good. — Doubtful. — Bad. Number. — Per cent. — Number. — Per cent. — Number. — Per cent. 16 soils (1917) — 6 — 37 — 2 — 13 — 8 — 50 10 soils (1912) .. 3 30 2 20 5 50 38 soils (1912) .. 11 29 13 34 14 37 The estimate for the 38 soils is in some measure tentative, but in the main it bears out the conclusion formed from the other soils of which we have more complete information. The evidence goes to show that about one-third of the area is not seriously charged with salt, about one-sixth is doubtful, while the reminder of the soils contain too much salt for profitable farming. In making this statement it should be remembered that some of the valuable lands on the banks of the Dalyup settlement and at Myrup are for practical purposes free of salt. Migration of salt to lower ground. A fact to be noted in connection with the presence of salt is that salt is not a fixture in the soil, but that it tends to pass from the high lands into the hollows. The reasons for this have already been explained. Table 12 shows at two places how salt tends to migrate to the low ground. At each place a sample was taken on a salt flat, and again on the hill-side adjacent to it. The figures refer to percentage of common salt. TABLE 12. Migrator of Salt to lower ground. ______________________________________________________________________________ Sample. Location. Common Salt. ______________________________________________________________________________ W. Baker's farm, S.W. Scaddan 1 .. .. Low-lying hollow .. .. .. .. .. •835 (a) 2 .. .. Higher Land adjoining .. .. .. .. •108 (a) ______________________________________________________________________________ Difference .. .. .. .. .. .. .. .. .. •727 ______________________________________________________________________________ Bush, six miles N.E. Scaddan— 11 .. .. Lake bottom .. .. .. .. .. 4.674 (a) 12 .. .. Higher land adjoining .. .. .. .. .350 (a) ______________________________________________________________________________ Difference .. .. .. .. .. .. .. .. .. 4.324 ______________________________________________________________________________ This tendency of salt to move downwards is clearly demonstrated by the figures. The numerous salt lakes and pans lying between Norseman and Esperance have formed in this way, a movement which is rendered possible by the undulating character of the country. (See photograph, Appendix A.) The occurrence of such lakes indicates that the higher land has lost part of its salt. The amount of rainfall in the district (Appendix C. Table 1) is of great importance in furthering salt movement, and Scaddan and Grass Patch are better situated in this regard than Lake View. Lands of a porous character, such as some of those around Scaddan, will lose salt faster than the grey loams carrying Morrell and tall Mallee. When the country is cleared the movement of salt from the higher lands will be greatly accelerated. This phenomenon is illustrated in the recent formation of salt pans in the York, Meckering, and other districts of the State subsequent to clearing. After clearing land the whole tendency of salt is to leave the higher ground, and a not unimportant factor in connection with salt in bush lands is that the worst effects—although the farmer may be unaware of salt
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