SOILS FERTILIZERS. G19 



fonnd to be better stocked with pbint food tban a productive field soil. Tlie 

 pine liumiis reacted weakly acid and liming slightly improved growing con- 

 ditions. 



Turpentine and carveue wlieu applied to a loam soil retarded the germina- 

 tion of corn, but this effect was apparent only during germination. No efl'ect 

 was observed with these products when used in the presence of tannin. Silver 

 pino-needle oil slightly retarded germination and chlorophyll formation. The 

 addition of ground pine needles to soil, while apparently not affecting germina- 

 tion, retarded the growth of the plant, which effect the author attributes to the 

 favorable influence of the pine needle cellulose on the activity of denitrifying 

 bacteria rather than to poisonous secretions. Formic acid strongly retarded 

 germination. Carvene and turpentine were both temporarily but increasingly 

 toxic to corn plants. The vapors of a number of the volatile conifer products 

 were found to be more or less toxic to Impaticns sultanii, rape, and cresses. 



The volatile products also retarded the formation and activity of soil fer- 

 ments, were more or less toxic to soil and milk bacteria, and, with one excep- 

 tion, more or less retarded the formation of nitrates from the ammonia of 

 urine. 



The oxidation of ammonium sulphate in beech humus was marked, while in 

 pine humus it was either small or negative. Comparative studies of the effects 

 of decomposing beech leaves and pine needles on the reduction of sodium nitrate 

 showed them to be about equally active. The volatile products had little retard- 

 ing influence on the reduction of sodium nitrate but markedly retarded the 

 bacterial decomposition of cellulose. 



It is concluded from these studies that the most of the different coniferous 

 products tested are toxic to higher plants, yeast, and bacteria, and that the 

 humus of pine forests, in contrast to the humus of beech forests, has a generally 

 unfavorable efi'ect on plant growth. 



A list of references to literature bearing on the subject is appended. 



Field test with toxic soil constituent: Vanillin, J. J, Skinnek (TJ. 8. Dept. 

 Agr. Bui. 164 (1015), pp. 9, pis. 4). — Pot and field experiments on the effect of 

 vanillin, a soil constituent (E. S. R., 30, p. 610), upon plant growth are reported. 



In pot experiments using a loam soil clover was stunted in growth and its 

 green weight reduced 53 per cent when 100 parts per million of vanillin was 

 present. In pot experiments with wheat using an infertile sand, an infertile 

 sandy loam, and a fertile loam vanillin in concentrations varying from 100 to 500 

 parts per million was harmful in the two infertile .soils and had no effect in 

 the fertile soil. The negative effect in the fertile soil is attributed to its stronger 

 oxidizing power. 



In field exiieriments on an acid silty clay loam with cowpcas, string beans, and 

 garden peas the harmful effect of the vanillin when added at the rate of 285 lbs. 

 per acre was noticeable from the beginning and throughout the experiments. 

 Six months after application this soil still contained vanillin, and when used in 

 pot experiments was harmful to wheat, cowpeas, string beans, and garden peas. 



The number and growth of protozoa in soil, J. M. Siikrman {Ccnibl. Balct. 

 [r/c], 2. AM., 41 ilOlJf), No. 18-23, pp. 625-630; ahs. in Internal. Inst. Agr. 

 [Rome], Mo. Bui. Agr. Intel, and Plant Diseases, 5 {1914), '^o. 9, pp. 1165, 

 1166). — Studies, using the dilution method, on sixteen soils representing various 

 types under vr.rious treatments as to cultivation indicated that the normal fertile 

 soil has a protozoa content approximating 10.00<) per gram. "The flagellates 

 constitute the greater portion of the i)rotozoan fauna of the soil, and not the 

 ciliates nor amoebie. Colpoda eucullus appears to be the most widely distributed 

 ciliate in soil, and may occasionally be found in numbers api)roximatiug 1,000 



