814 EXPERIMENT STATION RECORD. (Vol. 36 



obtained, but the ability to oxidize ammonia nitrogen to nitrate nitrogen was 

 materially altered. Continuous corn and wheat with no additions of manure 

 or chemicals brought about a relatively low oxidizing power in the soil complex. 

 The addition of manure, and to a less extent commercial fertilizers, materially 

 raised the oxidizing power, especially under continuous corn and wheat. 



The nutrition of soil bacteria, E. R. Allen {Mo. Bui. Ohio Sta., 1 {1916), No. 

 8, pp. 249, 250). — Experiments with extracts from a fertile soil before and after 

 the soil was ignited are reported, which show " that soil is superior to sand 

 for the support of nitrification and that the addition of humus improves the 

 sand while the addition of carbon black does not. Both humus and carbon 

 black remove substances from solution by absorption, but the actions of the 

 two . . . have been quite different. Ignition of soil, which would destroy 

 its humus, helped rather than injured its power to support nitrification. The 

 addition of humus to ignited soil exerted but little effect upon nitrification. 

 The experiments, however, do not confirm or disprove either the physical or 

 chemical theory." 



Influence of barnyard manure and water upon the bacterial activities of 

 the soil, J. E. Greaves and E. G. Caeteb {U. S. Dept. Agr., .Jour. Agr. Research, 

 6 {1916), No. 23, pp. 889-926, figs. i(?).— Experiments conducted at the Utah 

 Experiment Station are reported, dealing with (1) the bacterial activities of a 

 soil receiving a definite amount of manure and measured quantities of irriga- 

 tion water and kept fallow in pots under vegetation house conditions. (2) the 

 bacterial activities in a fallow soil under field conditions receiving known 

 quantities of manure and water, and (3) the bacterial activities of soil treated 

 as in (2) but producing a crop. The soil used was of sedimentary nature and 

 consisted of fine sand and coarse silt of fairly uniform physical and chemical 

 composition to a great depth. 



It was found that in a calcareous soil kept in pots for four months " the 

 temperature of the manured and unmanured averaged practically the same for 

 the period, but the temperature of the soil with 12.5 per cent of water averaged 

 1° G. higher than did soils with 22.5 per cent of water. The greatest number 

 of organisms developed on synthetic media from the soils receiving the greatest 

 quantity, 25 tons, of manure. There were more colonies developed from the 

 soil receiving 12.5 per cent of water than from any of the other soils receiving 

 higher quantities of water. 



" The ammonifying powers of the soil increased with the manure applied up 

 to 25 tons of manure per acre, but the greatest increase per ton of manure was 

 obtained in soil receiving 5 tons. The ammonifying powers of the soils In- 

 creased as the water applied increased until 20 per cent of water was applied. 

 The ammonifjing powers of soil receiving 22.5 per cent of water were not as 

 high as were those of soil receiving 20 per cent of water. The greatest increase 

 per unit of water applied was when the water was increased from 12.5 to 15 

 per cent of water. 



" The nitrifying powers of the soil increased as the manure and water applied 

 increased up to 25 tons of manure and 22.5 per cent of water. 



" The nitrogen-fixing powers of the soil were greatest in those pots receiving 

 10 tons of manure per acre. Increasing the water above 12.5 per cent but not 

 above 22.5 per cent slightly increased the nitrogen-fixing powers of the soil. 

 Nothing in the results indicated that the application of manure up to 25 tons 

 per acre and of water up to 22.5 per cent caused denitrification in the soil. 



" Bacteriological analyses of fallow field soil receiving none, 5 tons, and 

 15 tons of manure per acre and receiving none, 5 in., 10 in., 20 in., 30 in., 

 and 40 in. of irrigation water gave the following results : 



