INSTITUTE, PUSA, FOR .1919-20 S3 



C. The examination of the soils of the experimental 

 plots in the Punjab Field was completed. The results were 

 submitted by Dr. Harrison in December 1919 to the Com- 

 mittee appointed by the Board of Agriculture to review 

 the permanent manurial and rotation experiments at Pusa. 

 These experiments, . which were started in 1908, were de- 

 signed to find out the specific effect on soil fertility of the 

 more important organic and chemical manures, alone and 

 in various combinations, in a 2-year 4-course rotation. It 

 was also sought to determine how far soil fertility is affect- 

 ed by growing in rotation, leguminous crops (1) removed 

 from the land, (2) returned to the land in the shape of green 

 manures. The results obtained are noted below. 



The effect of applications of organic manures. Bulky 

 organic manures have a very appreciable effect in increas- 

 ing the total crop, but whereas with cereals the proportion 

 of grain is materially increased, the reverse is the case with 

 rahar (Cajanus indicus). The residual effect of rape cake 

 is inappreciable on the second crop, although its effect on 

 the crop to which it is applied is very marked. Rape cake 

 is therefore not as effective as farmyard manure when the 

 application is only once in a full cropping season. 



The effect of mineral manures. Of the manurial con- 

 stituents nitrogen, potash and phosphoric acid when applied 

 alone, the last is the only one which gives a distinctly 

 positive reaction in Pusa soil, but the combination of all 

 three gives the best results to the crop to which it is ap- 

 plied. In the case of cereals the use of phosphoric acid 

 increases the proportion of grain, but in the case of rahar 

 all manures increase the proportion of green matter. 



The effect of pulse crops in a rotation. It was noted 

 that the benefit due to the inclusion of legumes in the rota- 

 tion is positive so far as the yield of grain is concerned, 

 but the increases obtained are not of great magnitude and 

 there is practically no change in the weight of straw pro- 

 duced. In the case of rahar, the addition of a shallow- 

 rooted legume to the rotation resulted in slight decrease. 



