sept. 4, 1916 Influence of Barnyard Manure on Soil Bacteria 



903 



uniform for all plots. The plots had been treated since the spring of 

 191 1 in the manner described; the bacteriological analyses were made 

 during the summer of 19 14 and 191 5. 



The results reported in Table IV giving the number of colonies of 

 bacteria developing in four days on synthetic agar represent in every 

 case the average of a number of determinations made at the times 

 indicated. 



Table IV. — Number of colonies of bacteria developing in four days on synthetic agar — 



fallow plots 



Number 

 of deter- 

 mina- 

 tions. 



Treatment. 



No water; no manure . . . 

 5 inches of water; no 



manure 



10 inches of water; no 



manure 



20 inches of water; no 



manure 



30 inches of water; no 



manure 



40 inches of water; no 



manure 



No water; 5 tons of 



manure 



No water; 15 tons of 



manure 



5 inches of water; 5 tons 



of manure 



5 inches of water; 15 



tons of manure 



10 inches of water; 5 



tons of manure 



10 inches of water; 15 



tons of manure 



20 inches of water; 5 



tons of manure 



20 inches of water; 15 



tons of manure 



30 inches of water; 5 



tons of manure 



30 inches of water; 15 



tons of manure 



40 inches of water; 5 



tons of manure 



40 inches of water; 15 



tons of manure 



Number of colonies. 



May 12. 



3,475,000 

 3, OOO, OOO 



2, 960, OOO 



3, O3O, OOO 



2, 37O, OOO 



5, 660, OOO 



3, 570, 000 

 7, 700, OOO 



4, 000, 000 



5, 600, OOO 

 4, 600, 000 



6, 000, 000 

 4, 300, 000 

 4, 400, OOO 



6, 200, 000 



3, 600, 000 

 4, 450, OOO 



4, 600, 000 



July 25. 



12, 500, OOO 

 7, 600, OOO 



12, 9OO, OOO 

 12, 60O, OOO 



15, 800, OOO 

 11,860, OOO 

 23, 500, OOO 



20, OOO, OOO 

 11, 800, OOO 

 14, 200, OOO 

 19, OOO, OOO 



28, OOO, OOO 

 18, OOO, OOO 

 27, 400, OOO 



21, 200, OOO 



29, 400, OOO 

 14, 066, OOO 

 i9» 933. °°° 



Nov. 12. 



4, 100, 000 

 3, 700, 000 

 3, 700, 000 

 3, 950, 000 



5, 700, 000 



3, 800, OOO 



4, 300, 000 

 4, 800, 000 



6, 600, 000 

 11, 200, OOO 



7, 600, 000 

 4, 000, 000 

 6, 600, 000 

 9, 800, 000 



4, 400, 000 

 3, 200, OOO 



5, 933, 000 



6, 200, 000 



Average. 



5, 692, 000 

 4, 767, OOO 

 6, 520, 000 



6, 527, 000 



7, 957, 000 



7, 107, OOO 

 io, 457, 000 

 10, 833, 000 



7, 467, 000 

 10, 333, 000 

 10, 400, OOO 



12, 667, OOO 



9> 6 33> °°° 

 13, 867, OOO 

 10, 600, OOO 



12, 067, OOO 



8, 150, 000 

 10, 244, OOO 



It may be seen that the number of organisms are comparatively low 

 during the spring, in no case exceeding 8,000,000, while in July the number 

 becomes in most cases three or four times as many. In November the 

 number developing is about the same as in May. This method therefore 

 gives a maximum count in midsummer. The spring samples were taken 

 after all frost had left the ground, while the fall samples were taken before 

 55851°— 16 3 



