36 SOME ASPECTS OF THE INDIGO INDUSTRY IN BIHAR 
Manuring. 
Although indigo is a leguminous plant there is a copious development of 
nodules only after the early rains, so that it responds markedly to nitrogen 
applied in the form of organic matter such as leaf-mould, farmyard manure 
or oilcake. That nitrogen is required by the young crop is suggested by the 
waterlogging experiment carried out in September 1917, which is described 
above. This indication has been confirmed by the results of numerous field 
experiments and of several series of pot cultures. The chief effect of the orga- 
nic matter is to stimulate the seedlings and to help the crop to establish itself. 
If the soil is too poor at sowing time, numerous bare patches in the field 
develop and the crop looks thin and starved. Organic matter, on the other 
hand, leads to dark foliage and to strong growth. The effects persist till the 
break of the rains when they pass off due, in all probability, to the result of 
the intense nodular development which is such a feature of the crop at this 
period. Even during the rains, the indigo crop appears to make use of come 
bined nitrogen as the cereal crops like wheat and oats which follow indigo 
compared with those on fallow land never show any great vegetative vigour 
and exhibit all the signs of a reduced supply of available nitrogen. 
The effect of available phosphate on growth has been investigated by 
growing indigo in two sets of lysimeters—one filled with alluvial soil from 
Kalianpur and the other with Pusa soil. Kalianpur soil is exceedingly rich 
in available phosphate (0°318 per cent) while Pusa soil, when analysed by 
Dyer’s method, gives very low figures (0°001 per cent) for available phosphate. 
In spite of this the growth has always been greater in Pusa soil than in Kalian- 
pur soil as the following measurements taken on September 11th, 1918, 
show :—- 
Average height of plants in inches. 
Pusa soil .. a 4 oi 10°7 
Kalianpur soil ie a oe 5-0 
A second similar set of measurements were made on September 15th, 
1919, with the followimg results :— | 
Average height of plants in inches. 
Pusa soil .. ae a 4,5 36°4 
Kalianpur soil id ie a 20°1 
These figures afford no support to the view that manuring with super- 
phosphate will increase the growth of Java indigo. 
Pusa: 
20th November, 1919. 
