422 EXPERIMENT STATION RECORD. [Vr.l. 37 



" Large quantities of nitric nitrogen disappeared from the fallow soil during 

 the summer months. This is attributed to the growth of bacteria, which trans- 

 forms it into protein substances and not to denltrification. 



" The larger applications of irrigation, 37.5 and 25 in. of water, carry much 

 of the nitric nitrogen beyond the sphere of action of the plant, and this accounts 

 for the decrease in crop yield, which is often noted when excessive quantities 

 of irrigation waters are applied to a soil. The application of water to a soil 

 depresses the number of organisms which will develop upon synthetic agar in 

 alfalfa, oats, and potato soil, but increases them in fallow. The results obtained 

 with the corn are irregular. The ammonifying powers of all the soils, except 

 the alfalfa, were increased by the application of irrigation water. Water in- 

 creased the nitrifying powers of all the soils except the oats soil. 



" There was a difference of 2° F. in the temperature of the soil of irrigated 

 and unirrigated in favor of the unirrlgated. This difference in temperature was 

 perceptible to a depth of 4 ft. The number of organisms was higher in the 

 cropped than in the fallow plats, and this is probably due to the plant residues 

 left upon the cropped soil." 



The soils in the order of increasing ammonifying powers were alfalfa, oats, 

 corn, potato, and fallow soils. " By naming them in the order of increasing 

 nitrifying powers, they are fallow, corn, oats, alfalfa, ami potato [soils]. The 

 alfalfa not only feeds closer upon the nitric nitrogen of the soil than do other 

 crops but it also increases the nitrifying powers of the soil. Hence, it would 

 deplete the soil of its nitrogen more rapidly where the entire crop is removed 

 than would other crops. 



"The use of irrigation water increases the ba<terial activities of the soil 

 which render soluble the nitrogen, and where exce.ssive quantities of water are 

 usetl considerable of this is washed from the .<5oll, thus unnecessarily depleting 

 the soil of its nitrogen. This in turn gives diminished yields on the soil." 



The behavior of legume bacteria in acid and alkaline media, R. C. Salter 

 (Proc. Iowa Acad. Sci., 2S {1916), pp. S09S1S, figs. 2).— Experiments made to 

 compare the effects of acid and alkali on legume bacteria are reported, in 

 which it was found that " alfalfa bacteria are benefited by an alkaline reaction, 

 while the clover bacteria do best in a neutral or slightly acid medium. The 

 difference in behavior of alfalfa and rod dovor plants in acid soils is charac- 

 terized by a corresponding difference in the behavior of their symbiotic l>acteria." 



Effect of decomposing organic matter on the solubility of certain inorganic 

 constituents of the soil, C. A. Jensen {U. S. Drpt. Agr.. .Jour. .igr. Research, 

 9 (1917), No. 8, pp. 25S-268) .—This paper "deals with the solvent action on 

 certain inorganic soil constituents of the water-soluble decomposition products of 

 manures and other organic fertilizers. Soils were extractetl (1) with soluble 

 organic matter obtained from decomposing green manures and from stable 

 manures; (2) with soluble organic matter obtained from thoroughly flecom- 

 po.sed green manures; (3) with artificially prepared hinnus solutions obtaine*! 

 by hydrolyzing organic substances with acids: and (4) with osniose<.l organic 

 solutions derived from the decomposition of organic matter. In addition, stable 

 and green manures were added directly to the soil and the effect of this treat- 

 ment was noted (1) on the amounts of certain soil minerals dissolved out with 

 water, and (2) on the change produced in the specific electrical conductivity 

 of the soil. . . . Two types of soil, a clay loam and a sandy loam, were used. 



" In the four soil extractions these organic solvents removed from the soil 

 from two to five times as much calcium as was addetl to the soil with the sol- 

 vents. In most cases these solvents removed more magnesium from the soil in 

 the four extractions than was added with the solvents, the increase varying 

 from a siiuill fraotiDu to about 80 per » cnt. The amount of iron and phosphoric 



