1918] FIELD CROPS. 129 



ringed. Cryptomeria japonica and Prunus mutabilis, which had been shallowly 

 ringed, were attacked by insects with particular severity above but not at all 

 below the ring. 



Recent studies on sectioning and regeneration in plants, L. Daniel {Rev. 

 04n. Bot., 29 {1917), No. S39, pp. 65-12, figs. 11).— The author has made further 

 observations (E. S. R., 19, p. 728) on the production of anomalies by sectioning 

 and other forms of injury to growing plants. Decapitation of Eucalyptus glob- 

 ulus was followed by the development of the more juvenile form of leaves. 

 Carrot roots which had been sectioned or otherwise injured gave unusual forms 

 which are described. 



The cause of the disappearance of coumarin, vanillin, pyridin, and quino- 

 lin in the soil, W. J. Robbins {Alabama Sta. Bui. 195 {1917), pp. 49-64, pis. 

 2). — Experiments with sandy loam soils, one of neutral reaction and fair fer- 

 tility and the other of decidedly acid reaction, are reported. A list of cited 

 literature is included. 



It was found that " vanillin, coumarin, pyridin, and quinolin when added 

 separately to the soil used at a concentration of approximately 1,000 parts 

 per million of air dry soil produce a great temporary increase in the number 

 of bacteria which will develop on Brown's albumin agar. In the case of 

 vanillin and quinolin it is shown that this increase in numbers is preceded by 

 a decrease. The number of Actinomyces colonies in the soils treated with cou- 

 marin, vanillin, and quinolin decreases, reaching a minimum roughly corre- 

 sponding with the maximum in bacterial numbers. 



" Steam sterilizing of the soil used in these experiments produces material 

 toxic to the growth of wheat plants. Soil microorganisms destroy the toxicity 

 of the steamed soil under the conditions of the experiment. The effect on the 

 growth of wheat of vanillin, coumarin, pyridin, and quinolin in sterile soil 

 and in soil which has been sterilized, reinoculated, and incubated was compared. 

 In the inoculated soil the toxicity of the four compounds largely disappears. It 

 persists in the sterile soil. 



" Specific bacteria were isolated from the soils used which utilize coumarin, 

 vanillin, and pyridin as food sources. The bacterium feeding on vanillin will 

 in pure culture destroy the toxicity of vanillin [and coumarin] to wheat. . . . 

 The increase in the numbers of bacteria in the soils treated with the four com- 

 pounds and the disappearance of the toxicity of these substances in inoculated 

 soil is believed to be due to the fact that they serve as favorable food sources 

 to definite species of bacteria." 



FIELD CROPS. 



[Work with field crops on the Huntley reclamation project experiment 

 farm in 1916], D. Hansen {V. S. Dept. Agr., Bur. Plant Indus., Work Huntley 

 Expt. Farm, 1916, pp. 1-10, 12-14, 16-23, figs. 2). — This continues work pre- 

 viously noted (E. S. R., 36, p. 132), together with additional new experiments 

 Including methods of establishing irrigated pastures, methods of seeding clover, 

 and crop rotation experiments. 



The average yields of all crops in 1916 in the irrigated-crop rotation experi- 

 ments amounted to 4.64 tons of alfalfa, 11.17 tons for sugar beets, 240.3 bu. for 

 potatoes, 78.2 bu. for oats, 26.4 bu. for wheat, 36.3 bu. for corn, and 17.7 bu. for 

 flax. The maximum oat yield for 1916 amounted to 104.8 bu. per acre and was 

 grown in rotation with alfalfa (2 years) and potatoes. The maximum potato 

 yield, 401.7 bu., followed alfalfa for 3 years. The maximum sugar beet yield, 

 amounting to 17.93 tons, was obtained in a rotation of beets (manured) and 

 potatoes. 



