288 Prof. Bottomley. Effects of Nitrogen-fixing [Apr. 20, 



a mixed culture of Pseudomonas and Azotobacter applied directly to the roots 

 of other non-leguminous plants might benefit their growth also. 



The first experiments were made on oats (Avena sativa). Four 5-inch pots 

 were filled with sand freed as far as possible from organic matter and nitrates, 

 and given a sufficient dressing of phosphates, potash, and lime. Twenty oat 

 seeds were planted in each pot, and as soon as the young plants were about 

 1 inch high two of the pots were watered with a mixed culture of Pseudo- 

 monas and Azotobacter grown in the previously mentioned medium. The 

 plants were watered regularly with distilled water and allowed to grow until 

 the untreated plants exhibited signs of drooping. Each plant was then 

 carefully air dried and weighed, with the following result : — 



Untreated, average weight per plant (M2 gramme 



Treated 074 



an increase of 032 gramme, or 76 per cent. 



In 1908, field experiments were made on barley. Two plots, each having 

 an area of 484 square yards, were planted, one with seed moistened with the 

 mixed culture, the other with seed untreated. The land was very poor and 

 low in organic nitrogen, having carried oats in 1906 and barley in 1907. The 

 yield of grain per plot at harvest was : — 



Untreated 608 lb. 



Treated 691 „ 



an increase of 83 lb., or 13 - 6 per cent. 



On the same farm a strip of land was sown with treated seed through the 

 centre of a 34-acre barley field. It was found impossible at harvest to keep 

 the yield of treated seed separate from the rest, but samples of grain from the 

 treated and untreated parts were taken and analysed, and it was found that 

 the barley from the treated seed had the higher nitrogen-content. 



Milligrammes Weight of Milligramme 

 of N per cent. 1000 corns. N per corn. 



Untreated 1-55 48"5 075 



Treated 176 49"5 0"87 



Experiments on hyacinths (Galtonia candicans) grown in sandy soil. The 

 soil was dressed with lime in August, 1907, and remained fallow until April, 

 1908, when it was manured with cow manure — 10 tons to the acre. Bulbs 

 of equal size were then planted, 250 in each bed, a path of 14 inches dividing 

 the two beds. The treated bulbs were twice watered with mixed culture 

 solution, once in May and once in June, the control bed being watered with 

 pure water at the same time. The difference between the treated and 



