ON SOIL BACTERIA 



87 



the slag plot as on the untreated, but in April and August the position 

 of the two plots in this respect is reversed. 



Whenever possible during the season counts of the Azotobacter and 

 nitrate organisms were made. The results are set out in Table XL VI. 



TABLE XLV. BACTERIAL COUNTS (IN THOUSANDS) AT MARTIN'S 

 HEARNE AND HORNDON. (Agar-Albumose media) 



TABLE XLVI. COUNTS OF AZOTOBACTER AND NITRATE ORGANISMS 



IN THE SOIL AT MARTIN'S HEARNE AND HORNDON. 



(Thousands per grm.) 



There are no important differences between the numbers of Azoto- 

 bacter present on the treated and untreated plots at Martin's Hearne, 

 but at Horndon these soil organisms have been considerably developed 

 by the application of phosphates. 



The numbers of nitrate producing organisms have been greatly 

 increased on the basic slag plots at Horndon, a result which is in 

 keeping with the much greater amounts of nitrate found in this 

 soil throughout the season. (Tables XLIII and XLIV and Figs. 18 

 and 19.) 



