J> 



NOTES ON THE CHEMISTRY UE THE INARAS. 237 



D. — Soil taken about one mile from W'alfish Bay, north of the Kuisip 

 River, where Dr. Alacdonald indicated the possibility of cultivating 

 large wheat fields. 



All the samples in series A and B are from the Knisip River 

 estnary. These are of a most unnsnal character, differing 

 most essentially from ordinary desert sand, which consists almost 

 entirely of quartz grains, by having a large proportion of sinall 

 particles of white mica, a mineral containing a large percentage 

 of the valuable plant food potash. Sample A4 contained less 

 mica and more quartz than the rest. Sample Bi contained a 

 large proportion of various-sized lumps of dark shaly matter, 

 greatly decomposed. As these lumps are very different from 

 the surrounding sand, but are soft enough to be penetrated by 

 roots, they were separately analysed (see B3). 



Partial mechanical analyses were made of these soils, and 

 for the purposes of this paper it is sufficient to say that the 

 general type is a line sandy soil, perfectly porous, containing little 

 or no clay, and very uniform in grain, the particles being mostly 

 just under ^/-millimetre in diameter. 



The results of the analyses for reserve of plant foods are 

 given below in detail, the figures representing percentages, cal- 

 culated on the original air-dried soil. 



A. — Soils in which the I Xaras B. — Soils in which the 

 Plant thrives. ! Naras plant will 



not grow. 



A I A 2 A3 A 4 Bi l^2 B3 



Moisture 0.54 0.73 0.48 0.16 .. 0.50 0.53 14.84 



Loss on ignition ... 2.30 2.51 2.32 0.67 .. 5.14 1.91 9.25 



Chlorine 075 .152 .034 .011 .. 3 -.=169 1.099 7-02r 



S<jluble Salts 152 .384 .112 .040 .. 5-736' 1.84S ri.o6o 



Xitrogen trace trace trace trace .. .061 .014 -HO 



Lime 550 .500 .660 .316 .. .947 .656 1.634 



^fagnesia 066 .064 .126 .041 .. .411 -483 -601 



Potash 575 .573 -560 .079 .. .399 -240 .502 



Phosphoric Oxide.. .130 .139 .151 .069 .. .137 -102 .165 



The outstanding feature in connection with these soils is 

 the extraordinarily high percentage of the important plant food 

 potash, a substance particularly required by plants which produce 

 sugar. It is obvious that the potash is derived from the micas 

 of which the soils largely consist. It is noticed that sample A4, 

 which contains less mica than any of the others, has also the 

 least potash. There is, of course, considerably more total ]iotash 

 in the soils than is indicated by the above figures, wdiich give 

 only the amount available as plant food. As the mica gradually 

 decomposes more and more potash becomes " available," so that 

 a soil of this description has practically an inexhaustible supply. 



Since the soils on Avhich the plants will not grow, though 

 containing somewhat less potash than the good soils, are still 

 quite rich in this plant food, we have to look further for the 

 cause of their inferiority. The percentages of the other plant 

 foods in both series are very satisfactory, more so, on the whole. 



