780 
Journal of Agricultural Research 
Vol. V, No. 16 
(3) Calcium sulphate stimulates the growth of pure cultures of red- 
clover bacteria in nutrient solutions and in soil extract. The increase is 
as great with 0.01 per cent as with 0.1 per cent. 
(4) The root development of red clover is increased by calcium sulphate, 
0.01 per cent being apparently as efficient in producing this increase as 
0.1 per cent. 
(5) In small amounts calcium sulphate increases the yield of red clover 
and also the number of nodules. Concentration as high as 0.05 to 1 per 
cent, however, produces no increase in growth. 
(6) The application of elemental sulphur to Miami silt-loam soil 
increased but slightly the yield of clover and apparently did not affect 
root development or nodule formation. In producing this slightly 
increased growth 0.01 per cent was as efficient as were higher concentra¬ 
tions. 
(7) A review of the results of these experiments shows that calcium 
sulphate in soil does not produce any marked effect on the bacteria com¬ 
monly found on agar plates, but does increase the growth of the legume 
bacteria. It also increases the yield of red clover, which is accompanied 
by a greater root development and a greater number of nodules. 
(8) The addition of sulphur increases the ammonification, but decreases 
nitrification and the total number of soil organisms. It increases the 
yield of red clover but slightly and does not affect the root development 
nor the number of nodules. 
