TRANSACTIONS OF SECTION K. 807 
4, The Influence of Sulphates as Manure upon the Yield and Feeding- 
value of Crops. By T. 8. Dymonp, P.J.C., F. Hucues, and 
C, JuPE. 
A determination of the sulphuric acid in twenty Essex soils showed that they 
contained on the average ‘051 per cent. of SO,, an amount hardly more than 
one-third the percentage of the phosphoric acid in the same soils. Even this 
small amount of sulphuric acid is by no means entirely in a soluble state. The 
extraction of a soil by a 1 per cent. citric acid solution yielded only one-eighth 
of that extracted by concentrated hydrochloric acid, pointing to the existence in 
the soil of insoluble basic sulphates. In the light of these results, it may well be 
asked whether the available sulphuric acid in soils is sufficient for crops; for, 
taking the average composition of ordinary farm crops, the sulphuric acid absorbed 
amounts to 254 Ths. per acre, z.c. almost as much as the phosphoric acid, which 
amounts to 28 lbs. 
Field experiments have been made in Essex upon the use of sulphate as manure 
for oats (two experiments), cabbages (three experiments), peas (two experiments), 
and permanent pasture. In the case of chalky soils the sulphate was applied in 
the form of gypsum ; in the case of non-chalky soils in the form of sulphate of 
ammonium, as against chloride of ammonium. Except in the case of the 
cruciferous crop, the result was negative, the crops being’ more often decreased 
than increased by the application. In the case of the cabbages, 7.e. the crop 
richest in combined sulphur, the application of sulphate increased the crop in each 
of the three experiments. 
That with so small a quantity of sulphuric acid in the soil the crops yet find, 
as a rule, enough for their requirements is remarkable; but it must be remem- 
bered, in the first place, that rain-water contains an appreciable quantity of 
sulphuric acid, amounting in the case of a sample analysed at Chelmsford to 
1 part per 100,000. This for the average annual rainfall in Essex during the 
years 1895-1903 (500,000 gallons per acre) amounts to 50 lbs. SO, per acre, or 
double the requirements of average farm crops. In the course of some pot-culture 
experiments it was found that maize, clover, vetches, oats, mustard, and peas, 
even when grown in sand washed free from sulphate by hydrochloric acid, failed 
to respond to sulphate-manuring when exposed to the rain, and it was only when 
kept under cover during rain and watered with distilled water that striking 
differences were observed. 
Tn the second place, Berthelot and André have shown that the total sulphur 
in soils they examined amounted to nearly eight times the sulphur in the form of 
sulphate, the principal part of the sulphur being in the form of organic sulphur 
compounds. The present authors tind that in the presence of fermentative 
organisms a fairly rapid oxidation of this organic sulphur takes place. A soil was 
sterilised by heating at 100° for 1} hour on two successive days. One part was 
inoculated with soil-washings, the other not. Air, previously heated, was passed 
over both for 70 hours at the rate of 3 litres per hour. At the end of this 
period the sterilised soil contained 0256 per cent. of SO,; the inoculated soil 
contained as much as ‘0339, an increase of ‘0083 per cent., produced by 
fermentation. 
The question now arises whether, although crops grown under ordinary con- 
ditions do not respond in yield to sulphate-manuring, the application of sulphate 
may not influence the composition and feeding-value, and especially the proportion 
of albuminoids, which are, as a rule, sulphur compounds. For this inquiry a long 
series of determinations have been carried out of the total albuminoid nitrogen 
and sulphur in crops grown with and without sulphate of lime in presence of 
abundance of chalk. The crops included vetches, mustard, and oats grown in soil 
in pots, oats, mustard, and vetches grown in sand in pots, and grass and clover 
grown in the field. The sulphur was determined by Berthelot and André’s 
