Mallee - Part 2
The lime and magnesia are very similar to those of land under crop (Table 2—corrected average) and the sulphates and carbonates closely coincide. The details for common salt and the general average again show that this is certainly the important salt.
Bush Lands r emote from growing Cops.
the samples here, of which complete analyses were made, include No. 10 (tall mallee about six miles from Scaddan), No. 12 (morrell at N: Patch), No. 15 (tall mallee and ti-tree, McKinnon's), No. 16 (salmon gums), and No. 17 (small open mallee and ti-tree near Grass Patch). In each case the bush growth was apparently typical of important areas.
TABLE 4.
Bush lands.
___________________________________________________________________________________________________ Sample. Total Inorganic Common Salt. Sod. Sulphate. Sod. Carbonate. Lime. Magnesia.
Salts.
___________________________________________________________________________________________________ 10 .. .. .. •542 •367 •063 •051 •0054 •0064 12 .. .. .. •485 •332 •058 •052 •0079 •0139 15 .. .. .. •736 •499 •117 •068 •0095 •0198 16 .. .. .. •205 •136 •015 •028 •0128 •0086 17 .. .. .. •521 •337 •070 •056 •0037 •0043 ____________________________________________________________________________________________________ Average .. .. •498 •334 •065 •051 •0077 •0106 ____________________________________________________________________________________________________
Here again the sulphates and carbonates remain low, and, in the presence of a slightly increased lime and magnesia content, call for no special comment. The figures regarding those constituents are not less favourable than those relating to lands already discussed. In these bush lands also, t he most important salt constituent is certainly the common salt.
American experience.
in American experience with soil salts the occurrence of sulphates and carbonates often causes serious concern. in Utah investigations were carried out in seven counties, soils for analysis being taken from growing crop. the crop was Lucerne in one case; in the others wheat or oats. In these crops salt patches, varying from 10 to 100 feet in diameter, occurred where nothing would grow. Samples were taken from those sterile patches, also from parts of the fields producing good crops, also from places surrounding the bare patches where about half a normal crop was produced. The following figures published by the Utah Experiment Station* in 1916 given the main results of the investigation. Average of seven counties:— ____________________________________________________________________________________________________
* Utah Agric. Expt. Sta., Bulletin 145 (1916).
TABLE 5.
Total Soluble Salts, Chlorides, Sulphates and Carbonate in Alkali Soils as percentages of the dry Soils.
__________________________________________________________________________________________________________________ Part of Field producing. Total Inorganic Common Salt Sod. Sulphate. Sod. Carbonate.
Salts.
______________________________________________________________________________________________________ Total Inorganic .. } Best Crop .. •5130 •0931 •3080 •1100
Salts .. } Medium Crop .. •9494 •1811 •5505 •1017
No Crop .. .. .. .. .. .. 1•4645 •3119 •7415 •1184 _____________________________________________________________________________________________________
Regarding the sulphates, not only do the American soils show wide variations, but their amount is about 10 times greater than is found in the Esperance soils. The carbonates even under the best crops are about double those of Esperance, whose soild moreover are well supplied with lime and magnesia.
In those soils the carious salts appeared in conjunction, and the effect of the large amounts of sulphates, and the carbonated was added to that of the sodium chloride (Common salt) present.
Sulphates and Carbonates.
In investigating a salt problem in soils, the occurrence of sulphates and carbonates is always a possible source of trouble, and to find a low percentage of chloride (common salt) is no guarantee that he soil does not suffer from other soluble salts. The complete analysis made of certain of the Esperance soils gives reassurance however in this important matter, and it can be definitely stated that the occurrence of soluble sulphates and carbonates in those soils need cause no special concern. Their presence will, to some extent, accentuate the evil effects of the sodium chloride present, but the amounts are relatively small. Owing to this fact and to their relative constancy in the soils, the occurrence of sulphates and carbonates meed not be considered as an important variable. For practical purposes it now becomes possible, therefore, to confine attention to the sodium chloride content alone.
Data available for Sodium Chloride.
Of the samples of soils and subsoils taken, 36 were sent to three different analysts. In the absence of a standard method of soil analysis no absolute conformity is to be expected in the results. Where one chemist differs from another, this does not imply that either of them is in error. Such variations may be due to the particular methods of examination. The following results were approximately obtained by the three analysts, on the average of 36 samples, which were supplied to them in common:—
TABLE 6.
Average results for Sodium Chloride (36 samples).
________________________________________________________________________________________
— Mann. Dunn. Simpson. Average.
________________________________________________________________________________________ Average, percentage .. .. .. •274 •236 •257 •255 Average = 100 .. .. .. .. 107 92 101 100 ________________________________________________________________________________________
