24 SOME ASPECTS OF THE INDIGO INDUSTRY IN BIHAR 
grown successfully on several estates and is being further improved by selection 
at Pusa. 
Type 20. This has been selected from the Java-Natal indigo obtained 
from the Koeto Sani Estate in Java. It is a tall rapidly growing perennial 
indigo which resembles the original Java-Natal first introduced into Bihar. 
A number of plants of the original sample have given two crops of seed and have 
survived the intervening monsoon. Selection is in progress on this type by 
which the vigour is being increased and by which the power of repair after 
cutting back is being improved. 
As the soil conditions of the various indigo estates in Bihar vary con- 
siderably, it is quite possible that one type of plant will not prove to be the 
most efficient in all cases. The soils of most of the estates in the northern 
portion of the indigo tract are heavier and moister than those of the south. 
Different types may, therefore, be required for the various tracts. Should this 
be found to be the case, it will add considerably to the labour of selection. 
Improved drainage. 
As poor soil aeration has been found to be an important factor in the well- 
being of the indigo crop, it follows that any iniprovement in the general or 
local drainage of Bihar during the rains would tend to reduce wilt. Regarded 
in its widest aspect this is a large subject as the efficiency of the local rivers, 
on which the monsoon drainage is based, depends on the rise and fall of the 
Ganges, on the area under inundation in Bengal and on the obstructions (in the 
shape of embankments) to surface drainage in Bihar. The wider aspects of the 
subject, however, demand attention as there can be no question that the flood 
level in Bihar is rising and that the damage done to the monsoon crops is 
increasing. Improvements in local drainage are in many cases possible by 
the adoption of the Pusa system, a method which has been taken up already 
on a number of estates.! 
APPENDIX. 
Variation of CO, in the soil gas from the different plots in the Botanical Area, 
Pusa, during the period January to November 1919. 
Apparatus and methods employed. 
A hole was first made in the plot by means of a half-inch auger. A brass 
tube (2 feet 3 inches in length, inner diameter 0-6”) sharpened at one end with 
1 Bulletin 58, Agr. Res. Inst., Pusa, 1915. 
