Albert Howard 



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during the rain. That the rise of the subsoil water combined with the 

 consolidation of the surface soil does interfere with soil-aeration is shown 

 by the periodic determination of the soil gases at Pusa during 1919 

 (Table I), a year when rainfall was below the average and when the 

 movements of the ground water were very slight. 



During this year, indigo wilt was almost negligible and only made 



Fig. 2. Rise and fall of the river and well levels at Pusa in 1919. 



its appearance at Pusa on two occasions, between July 23rd and Aug. 7th, 

 and again between Sept. 1st and 23rd. A reference to Fig. 2 will show 

 that these attacks followed a rise of the ground water combined with 

 heavy rain. During these periods, the roots of many of the affected 

 plants were exposed and compared with those of normal individuals. 

 In all cases, most of the nodules and fine roots of the wilted plants were 

 dead except a very few near the surface of the ground. The root tips of 



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