42 REPORT OF THE AGRICULTURAL RESEARCH INSTITUTE 



cultivators. Hybridization work, on the other hand, begun 

 without exhausting the possibilities in selection, might 

 easily prove to be unnecessary even if, after many years 

 of work, it proved successful. 



Soil ventilation and drainage. For some time the 

 existence of an important limiting factor in crop produc- 

 tion has been suspected in India, namely, the want of suffi- 

 cient air for the soil organisms and roots of plants. A 

 large number of observations on plant growth have been 

 made at Pusa, at Quetta and in other parts of India which 

 can be most easily explained by a want of proper aeration 

 of the soil. All the evidence obtained, as well as the results 

 of a number of experiments, have been consistent with this 

 view. During the year, a preliminary statement of the 

 case was put forward in Bulletin 52 in which some of the 

 work in progress was outlined. The volume of the gases 

 in the soil is naturally bound up with the amount of water 

 present and this in turn opens up many questions with 

 regard to irrigation and to the saving of water in crop 

 production. The practical applications of the views put 

 forward are many and obvious. In some cases, they have 

 already been translated into practice. The regulation of 

 the air supply of the soil in the case of Java indigo has 

 given important results which have been indicated above 

 under that crop (p. 35). There seems little doubt that 

 the future of the indigo industry in Bihar depends on the 

 copious aeration of the soil in which this crop is grown. 

 In the case of green-manuring in India, soil ventilation 

 appears to be one of the chief factors on which success 

 depends, while in tobacco cultivation in Bihar there is 

 reason to believe that the cost of manuring can be mate- 

 rially reduced if means of permanently aerating the soil 

 are adopted. 



Perhaps the most important direction in which the air 

 supply of the soil can be increased in Bihar is by means 

 of surface drainage. A method has been worked out at 

 Pusa and is now in successful operation on several of the 

 estates in Bihar. This consists in dividing up the area 



