774 ie TRANSACTIONS OF SECTION \M. 
(iv) The Precision of the Irish Barley Experiments. 
By Dr. F. E. Hacxert. 
(v) The Burbage Breeding Experiments. By Major C. C. Hurst. 
MONDAY, SEPTEMBER 15. 
Joint Meeting with Section I.—See p. 669. 
TUESDAY, SEPTEMBER 16. 
The following Papers were read :— 
1. The Partial Sterilisation of the Soil by means of Caustic Lime. 
By H. B. Hutcuinson, Ph.D., and K. MacLennan, B.Sc. 
The main line of work has been to determine the efficiency of caustic lime 
as a partial sterilisation agent for field conditions, but from the results obtained 
it would appear probable that a closer inquiry into the effects of lime and of 
chalk on field soils and of the general practice of liming would repay further 
investigation. 
Various types of soils have been submitted to periodical chemical and 
bacteriological analysis and show great differences in their behaviour on treat- 
ment with caustic lime in different proportions and with chalk. The factor 
limiting bacterial activity and the proportion of ammonia and nitrate may be 
successfully removed by applications of caustic lime, but the possibility of a 
profitable adoption of the method in practice—with the exception of market- 
garden conditions—can only be decided after reference to special conditions, 
such as type of soil, intensity of cultivation, type of crop and prevailing prices. 
The action of lime may be regarded as being intermediate in character between 
that exercised by heat and mild antiseptics. The micro-flora and fauna of the 
soil are not affected to such an extent as by heat, but the amount of chemical 
oe is much greater than that caused by antiseptics as carbon bisulphide and 
toluene. 
After a certain incubation period, the length of which depends on the char- 
acter of the soil and the amount of lime applied, soil bacteria begin to multiply 
rapidly and lead to large increases in the amount of available nitrogen. Below 
the partial sterilisation limit the production of food would appear to be due to 
initial chemical action of the lime in breaking down some of the more complex 
soil constituents, so that the total ammonia and nitrate are in some cases in 
proportion to the amount of lime applied. Above the partial sterilisation point 
this relation no longer holds. 
The value of an addition of chalk depends largely on the amount of carbonate 
initially present in the soil and the character of the reserves of soil nitrogen. 
In some cases its action is considerable, whilst in others it is negligible. 
Table showing the Effect of Caustic Lime and of Chalk on the Production of Ammonta 
and Nitrate in various Soils. (Parts per million of Dry Soil.) 
| dy | Chalk 
oe Caustic Lime (per cent.) | (per cant) 
0 | 01 | o2 | o8 | o4 | 05 | 10 1:0 
| | | 
Rothamsted. .| 8 | 21 | 40 | 44 | 46 | 54 | 69 |] 8 
Chelsea. . .| 3841 36 41 49 | 57 | .59 75 |) 33 
Wobury (acid) .| 12 | 29 | 45 48 64 | 60 | 35 49 
Craibstone . . | 23 | 18 | 27 36 | 44 | 49 | 90 33 
| 
