226 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 
Soil Alkali, A Study of Methods of Determining. By D. W. Pittman (U.S.A. 
Exp. Sin., Utah, Bull. 170, August 1919 ; 8 figs.). — Reports some comparisons 
of different methods of testing alkali soils both as to results and relative variability, 
a study of some of the irregularities in the water-extraction method of testing 
for sodium carbonate, and a study of crop germination as an index of alkalinity. 
A. P. 
Soil, Cause of Chlorosis (lime-induced) and Availability of Iron in the. 
By P. L. Gile and J. O. Carrero {U.S.A. Jour. Agr. Res. xx. No. 1, Oct. 
1920, pp. 33-62 ; 2 plates). — Soil surveys of cultivated plants show that a parti- 
cular type of chlorosis occurs only on calcareous soils, and this appears to be due 
to the addition of carbonate of lime to soils producing normal calcifugous plants 
and causes these soils to produce chlorotic plants. From the analyses of the ash 
of chlorotic plants it would appear that a deficiency of iron in the ash is one cause 
of the chlorosis, and that excess of lime is another cause. Rice, a plant sensitive 
to lime, does not appear to be sensitive to the alkalinity of carbonate of lime 
except as this alkalinity influences the availability of iron in calcareous soils. 
Pure organic compounds of iron were not efficient sources of iron for rice plants 
in calcareous soils. Stable manure, and green manure when used in quantity, 
however, enabled the plant to secure more iron. The availability of iron in 
calcareous soils appears to be slightly greater near the optimum water content 
of the soil than at the higher percentages of water. — A . B. 
Soils, Effect of Calcium Sulphate on the Solubility of. By M. M. McCool 
and C. C. Millar (U.S. Jour. Agr. Res. xix. No. 2, April 1920, pp. 47-54). — Six 
different soils were treated with a saturated solution of calcium sulphate. In 
one series of experiments, the mass was transferred to filter paper, permitted 
to drain, and then transferred to containers. The rate of formation of soluble 
substances was determined by the freezing-point method. This was found to 
increase the solubility of the soil considerably. 
In another series, the amount of soluble material was reduced to a minimum 
by washing with distilled water, and the residuary effects of the treatment 
on solubility determined. The calcium sulphate treatment was found to have 
resulted in a very large increase in soluble substances. 
Two soils of different texture and organic content were treated with a 
saturated solution of calcium sulphate, a decinormal solution of calcium phos- 
phate, and a combination of the two. The soils were then washed and rate 
of formation of soluble salts determined. The calcium sulphate increased the 
solubility in each soil, while the calcium phosphate decreased the rate of formation 
of soluble substances. When the two substances were used together a neutral 
effect was produced. — A. B. 
Soil Fauna of Agricultural Land, A Preliminary Survey of the. By P. 
Buckle (Ann. App. Biol. vol. viii. Nov. 1921, pp. 135-145). — This research 
was undertaken to ascertain whether (1) arable, (2) freshly broken-up pasture, 
and (3) permanent pasture lands each had a characteristic insect fauna, and 
the results indicate that they had. 
(1) Arable land showed no characteristic fauna, but the predominant species 
were those found on pasture. 
The difficulty of correct records is on account of the species of insects 
varying with the particular crop at the time. 
(2) In freshly broken-up pasture land there is a corresponding increase 
in the fauna as vegetative growth increases. 
(3) Permanent pasture land shows more stable distribution and number of 
soil fauna, which is accounted for by the fact that grassland bears a vegetative 
covering when there is little vegetation on arable land. 
As there is no ploughing or working of the soil, which exposes insects to 
harsh climatic conditions and bird attack, the hibernation of species and the 
period of quiescence proceeds normally. 
The difficulty in sampling is that dominant species are exaggerated, whilst 
rarer species may be overlooked, unless a very thorough survey is undertaken. 
G. F. W. 
Soil, Physical State of, Effect on Crop Growth and Season upon. By 
D. R. Hoagland and J. C. Martin (U.S.A. Jour. Agr. Res. xx. No. 5, Dec. 
1920, pp. 397-404 ; 4 figures). — The physical state of certain soil constituents is 
influenced to a marked, degree by the concentration of the soil solution. The 
colloidal state of the soil suspension undergoes significant alterations during the 
season. A large increase in colloidal matter is noted when the soil solution is 
