210 THE LIVING ORGANISMS OF THE SOIL [chap. 



grown for the first time on heavy land in a new district 

 has been observed to fail completely, the failure being 

 attended by a complete absence of nodules from the roots. 

 Success does not, however, invariably follow inoculation. 

 In the first place, it may be necessary to bring the soil 

 itself into the proper condition for the growth of both 

 crop and the bacteria, the natural absence of which is 

 of itself evidence that the soil is unsuited to their 

 maintenance. Liming and dressings of basic slag and 

 potash salts are generally the necessary preliminaries 

 to any satisfactory growth of leguminous crops on 

 indifferent s.oils. Even then the first inoculation may 

 show comparatively little effect, the plant still remaining 

 weakly, though most of the individuals may show 

 nodules. The inoculation only supplies a very limited 

 number of bacteria compared with the population in 

 a normal soil. It is only when the crop comes to be 

 sown a second time that vigorous growth is obtained. 

 It is within the author's experience that a first sowing 

 of lucerne on land that had never carried the crop 

 before gave weakly, unnodulated plants. A culture of 

 nodule organisms was sprayed over in early spring 

 without benefit, whereupon the crop was ploughed up 

 and resown, the seed being inoculated before sowing. 

 The plant was still poor, though generally nodulated ; 

 accordingly it was again ploughed up and resown, with 

 the result that a good crop of lucerne was established. 



Inoculation with soil from a field which has pre- 

 viously grown the crop about to be sown has often 

 proved a signal success in reclaiming the poor heath 

 lands of East Prussia, by the system of green manuring 

 worked out by Dr Schultz at Lupitz. Very large 

 areas of barren sandy heath land have been re- 

 claimed and rendered fit for the cultivation of the 

 ordinary crop by a system of growing lupins and 



