i6 



Journal of Agricultural Research 



Vol. VI. No. I 



tard did not do well in sand cultures ; growth was very irregular. Because 

 of the size of the jars and the irregular growth of the crops it will be 

 necessary to repeat the experiment. 



EFFECT OF CARBON BISULPHID IN REINOCULATED SOIL 



In the first part of this paper it has been shown that if soil treated with 

 carbon bisulphid is reinoculated with fresh soil the bacterial processes 

 are altered. The increase in number of bacteria attains a maximum 

 much sooner and begins to decline earlier than in soil treated with carbon 

 bisulphid but not reinoculated. This is also noted in the formation of 

 soluble nitrogen. In order to record the effect on plant growth, the fol- 

 lowing experiment was planned. Six jars with 9 kgm. each of Miami 

 silt-loam soil were used. Two months after treatment with carbon 

 bisulphid, 2 per cent of untreated soil were added to jars 5 and 6. An 

 equal amount was removed before the original soil was added. All of 

 the jars were kept for another month before planting. 



Plate"counts three months from the date of treatment showed a decided 

 increase in number of bacteria in the carbon-bisulphid soils. No appre- 

 ciable difiference existed between the carbon bisulphid and the carbon- 

 bisulphid reinoculated soil. 



The effect of treatment on nitrate content is evident from the following 

 figures: If the nitrate nitrogen at the beginning is 100, then the control 

 after three months is 370, carbon bisulphid is 50, and carbon bisulphid 

 plus 2 per cent of the original soil is 44. Here, again, the inverse rela- 

 tion of number of bacteria and nitrate content is noted. 



Protozoa were found in all of the soils and apparently in about the 

 same number two months after treatment as in the original soil. 



The effect of this treatment on the growth of oats and com may be 

 seen from the figures in Table XVI. 



Table XVI. 



-Effect of carbon bisulphid on the growth of oats and corn in reinoculated 

 soil 



No. 



Soil. 



Miami 

 ...do.. 

 ...do.. 



...do.. 

 ...do.. 



...do. 



Treatment. 



Control 



....do 



2 per cent of carbon bisul- 

 phid. 



do .., 



2 per cent carbon bisulphid 

 plus 2 per cent of the orig- 

 inal soil. 



do 



Weight of first crop, oats. 



Green. 



Gm. 

 168 

 178 

 178 



185 

 178 



215 



Dry. 



Gm. 



SI 



50-75 

 50 



54 

 51-5 



61.5 



Aver- 

 age. 



Gm. 



^50. 9 



56.5 



Weight of second crop, 

 com. 



Green. 



Dry. 



Gm. 



28 



30 

 2,2, 

 26 



26 



Aver- 

 age. 



Gm.. 



■ 29 



29-5 



■ 24 



