The chief objects of the investigation were
(1) to compare the "lime requirements" of certain acid soils
as determined by methods in use in various countries and to
compare the effects of adding lime in tha laboratory aad in
the field (2) to compare the results obtained by the various
methods which have been proposed for the determination of the
saturation value of the soil and (3) to determine the amount
of Calcium absorbed in the field, its effect on the other
bases of the soil and on the crop yield.
For this purpose 10 plots were laid down, 5 in
duplicate, the soils all containing practically the same
amount of clay 22 - 25'3, but varying amounts of organic matter
10 - 21f. .. short discussion on the methods of estimating
organic matter is given, the method used being that of
Robinson's, i.e. reduction of sulphuric acid to sulphur
dioxide by the carbon of the organic matter and estimation of
the sulphur dioxide evolved. The results agree well with
the "loss on ignition" and the method would appear to be very
useful in routine work. The total nitrogen was also
estimated, but no definite ratio could be established between
the carbon and the nitrogen - the ratio carbon to nitrogen
varied between 13 and 17 - or between the nitrogen and the
The pH of the plots in water solution varied between
4.5 and 5 and between 3.7 and 4.2 in N Kc1 solution, i.e. they
were highly acidic.
The various methods used in determining the "lime
requirements" were (1)Christensen- Jensen - lime rexuired to
give pH 7 found by titration with Ca(OH)2. The buffer power of the soils calculated according to his method is given.
(2) Kappen's - Lime required to remove the "hydrolytic
acidity" found by shaking soil with calcium acetate or sodium
acetate and titration of filtrate with sodium hydroxide.
More acidity was liberated by treatment with calcium than -,vith
(3) Daikahura's - Lime required to remove "exchange acidity"
found by shaking soil with normal potassium chloride and
titration of filtrate with standard sodium hydroxide.
(Kappen's type3 of acidity : "Ijydrolytic Acidity ", ",,Xchange
Acidity ", "Neutral Salt Decomposition ", and "Active Lcidity"
and also Page's theory that these are not different types, but are all of one kind differing only in degree are discussed.
The various phenomena can be explained by assuming greater
amounts of replaceable hydrogen present in the soil complex
as the acidity increases).
Hutchison and McLennan - Lime requirement by determining the
amount of calcium absorbed by soil from a solution of calcium
bicarbonate. The errors of the method pointed out by various
observers are given.
The results show that most lime is required to give
pH 7, the hydrolytic acidity method less, Hutchison- licLennan
still less, and least of all by exchange acidity method.
It is pointed out that pH 7 is perhaps unnecessarily high
for many crops so thatAamount of lime could be decreased.
It was also found that time taken for suspension of soil and
calcium hydroxide to reach e,uilibrium was longer than 48 hrs.,
96 hours and 120 hours being necessary in some cases. This
makes the method too long for routine use. The exchange acidity methods give amounts of lime which are tm low for practical purposes.
The Hutchison -McLennan and Kappen's method give results which
appear to be suitable. Kappen's method would be useful in
practice as being .,uicker than Hutchison- McLennan, but the
amount of soil used 100 gms. could be decreased and 200 c.cs. solution taken.