183 



the details of Tacke's experiments ;(^^ he found that in sandy soil an ap- 

 pKcation of lime corresponding with 24 cwt. per acre did not destroy the 

 bacteria, and the results obtained with peaty soils were similar. It is 

 therefore, concluded that in the field experiments above described the 

 injury which still remains unaccounted for, was, at any rate, not due 

 to the lime. The subject is now being investigated jointly by Drs. 

 Salfeld and Tacke, and no doubt some explanation will, before long, be 

 forthcoming. 



IMPORTANCE OF SOIL INOCULATION IN AGRICULTURE. 



It may be remarked, in the first place, that the results of Salfeld' s 

 and other experiments show that there exists soils which are so poor 

 in nodule bacteria (Bacillus radicicola) as to require inoculation before 

 certain leguminous crops can be suceessfully grown on them in ab- 

 sence of arailable nitrogen in the soil. 



The most striking results were obtained with the poorest soils, new- 

 ly cultivated peaty land giving luxuriant crops when suitably inocu- 

 lated, after being limed or marled, and sufficiently manured with po- 

 tash and basic slag; whilst without inoculation the same crop com- 

 pletely failed. The plants successfully grown were red, white, and alsike 

 clovers, lotus corniculatus, serradella, horse beans, field and garden 

 peas, etc. The same holds with sandy soils, which when inoculated 

 gave good crops of lupins, serradella and clover. No experiments 

 seem to have been made as yet with new loamy soil, but there can be no 

 doubt that such land could be successfully brought under cultivation 

 by similar treatment. On old cultivated land inoculation has not the 

 same importance, but experiments alone will show whether it is bene- 

 ficial or not. 



Whether the bacteria of the different root nodules are different spe- 

 cies, or modifications of one species, it is clear that judgment must be 

 exercised in selecting soils for particular crops ; and in some cases it 

 may be desirable to experiment with different soils. But when a field 

 is once suitably inoculated the soil of the field is available for any 

 number of other fields which may require inoculation for the same 

 crop. The quantity of soil to be applied will depend on the number 

 of bacteria present in the soil, and also on the physical nature of the 

 soil ; the finer the soil, the better it can be distributed, and a small 

 quantity of a readily pulverised soil will, of course, go further than a 

 large quantity of soil which forms hard lumps. The amount of soil 

 necessary may thus vary from about half a ton to a ton and a half per 

 acre. Thorough incorporation with the land is most important to en- 

 sure proper infection of the young plants. 



When a leguminous crop fails, the first thing to do is to examine 

 the roots to see whether nodules are present ; if absent, inoculation ex- 

 periments should be made the following year. But there may, of 

 course, be other reasons for the failure, such ag acidity of the eoil. 



13. Mitthailungen d. Ver. z. Ford. d. Moorkultur, 1895. Bd. 13. No. 22. 



