TRANSACTIONS OF SECTION M. 777 
4, Nitrification in some Pasture Soils. By C. T. Grunonam, FIC. 
The author gave an account of some observations on the processes of ammoni- 
fication and nitrification in some pasture soils containing a high percentage of 
organic matter and very little carbonate. It is known that nitrification is 
reduced to a minimum in a pasture soil rendered acid by the continued use of 
ammonium salts as manure; and an investigation has been made of the behaviour 
in this respect of soils naturally acid or in process of becoming acid. The soil 
chosen for most of these experiments was one apparently intermediate between 
a true ‘moor’ and a true ‘fen’ soil. It is very dark in colour, contains between 
30 per cent. and 40 per cent. organic matter, and only traces of carbonate, but 
the soil water is neutral in reaction. It behaves as an acid soil in that, when 
seeded into a culture solution containing glucose, with ammonium chloride as 
the only source of nitrogen, a growth of moulds appears and the culture becomes 
distinctly acid. On the other hand, the soil itself is capable of bringing about 
rapid nitrification. The plan adopted was to follow the fate of the nitrogen 
in peptone added to the soil beyond the ammonia stage and to determine also 
the nitrates formed. It was found that nitrification sets in almost at once and 
proceeds very rapidly. Ammonium sulphate is also quickly nitrified, though 
the soil very soon takes on a faintly acid reaction. 
Figures were given of a series of determinations of ammonia and nitrates 
over a considerable period in portions of soil to which peptone was added; 
these were compared with similar figures obtained from normal soils and from 
soils naturally acid. Other details of the behaviour of these soils were given. 
A note on the use of ‘nitron’ for the determination of nitrates in aoil 
extracts was appended. 
5. The Effect of Soluble Humates on Nitrogen Fixation and Plant 
Growth. By Professor W. B. Borromuny, M.A. 
The observations of Heinze, Krzemieniewski, and others on the influence of 
soluble humates on nitrogen-fixing bacteria suggested the possibility of using 
a material rich in soluble humates as a medium for introducing cultures of 
nitrogen-fixing bacteria into the soil. It was thought that such a medium might 
also benefit the nitrogen-fixing organisms already present in the soil. 
It has been found that the insoluble humic acid which is present in large 
quantities in peat can be readily converted into soluble humate by the action 
of certain aerobic soil bacteria. Peat after treatment with these organisms is 
sterilised and then inoculated with a culture of nitrogen-fixing organisms. This 
prepared peat can then be used for soil inoculation, either by direct application 
to the soil, or preparing from it a culture solution. 
A mixture of 9 oz. of poor garden soil and 1 oz. of prepared peat after 
seventeen days’ incubation at 26° C. gave the following results :— 
Soil+sterilised prepared peat ...... (a) "717 grm. N per 100 grms. soil. 
(5) “709 2” ”» > 9 
Soil+active prepared peat ......... a (a) e'792he x5 nf: 
(5) “789 ” ” ”» ” 
An average gain of 77 mgrms. of N per 100 grms. soil. 
A culture solution was obtained by mixing 2 grms. of the prepared peat and 
‘5 orm. of sugar in 100 c.c. of distilled water, and incubating at 26° C. for 
twenty-four hours. A mixture of 12 oz. of soil and 75 cc. of this culture 
solution, after seventeen days’ incubation at 26° C., analysed as follows :— 
Soil+sterilised culture ............ (a) *241 grm. N per 100 grms. soil. 
(d) 251 9 ” 9? »”> 
Soil+living culture ............... (a) 348 —,, > 55 * 
(b) 338 bed ”) ”) 2? 
An average gain of 97 mgrms. of N per 100 grms. soil. 
Pot experiments in the greenhouse and plot experiments in the open showed 
that the prepared peat, in addition to its effect on nitrogen fixation, has a direct 
influence on promoting plant growth. This is probably due in part to the 
