38
THE JOURNAL OR INDIAN BOTANY.
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Table 4 Area IV
Per cent.
Saccharum Munja Roxb. ...
96-6
Eleusine aegypfciaca Desf.
Indigofera linifolia Betz. ...
1*36
Eragrastis ciliaris Link, var
Indigofera cordifolia Heyne .
- 68
brachystachya Boiss.
Phaseolus trilobus Ait.
- 34
Perotis latifolia Ait.
Orotalaria Burhia Ham.
- 34
Panicum ram o sum Linn .
Indigofera enneaphylla Linn .
- 34
Cyperus niveus Reis.
Calotropis procera R. Br . ...
- 34
Eragrostis tremula Hochst . Cenchrus catharticus Delile .
2.C. Soil Analysis . — ‘The soil throughout; the four areas is an almost pure sand, but in Area II there is a perceptible proportion of humus. Treatment of the soils with dilute acid indicated the presence of carbonates. No complete analysis was attempted, but magnesium carbonate seemed to be present in greater quantity than the calcium salt.
By treatment of weighed samples with measured volumes of standard acid, and titrating the remaining acid with standard alkali, carbonates were estimated as C0 2 . Again by calcining weighed sam- ples, allowing them to cool in an atmosphere free from C0 2j and weighing again, it was assumed that the loss of weight would represent 00 2 plus humus. By subtracting from these figures those obtained previously for C0 2 alone, the amount of humus was estimated. The figures were as follows : —
Table 5
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Humus plus CO s
CO 2
Humus (by difference)
Area
Per cent.
Per cent.
Per cent.
I ...
2*12
0*77
1*35
II ...
4*37
1*50
2*87
Ill ...
... 2*48
1*38
1*10
IV ...
3*38
2*56
0*82
The general aspect of the vegetation, and the prevalence of families usually regarded as halophytic, suggested that sodium chloride might be present to an appreciable extent, but repeated tests of filtered soil extracts with dilute silver nitrate, gave negative results in each case.
Erom these results it did not appear, with the possible exception of area II, that the differences in the vegetation could be caused by differences in the chemical nature of the soil.
