son, PHYSICS, CHICanSTRY AND MICROTilOr.Or.Y 



1 25 1 



Fertility of Tchernoziom non-manured, manured, sterilised and chloroformed. 



Manures applied 



and mode of treatment 



Ml" the samples 



of 



tchernoziom 



Average weight in gr. 



;)f the total vcsetable mass 



(seed and straw) 



Ratio between the vegetable masses, 

 that of the conliol series 

 being taken as the unit 



I ajjril 

 fallow 

 j (layer 

 fromoto 



on 

 april 



fallow 

 (layer 

 from 



17,7 to 



on 

 cleared 



land 

 (layer 

 from 



o to 



on 



3 years 

 lucerne 



soil 



(layer 



fromoto 



april 



fallow 



(layer 



fromoto 



on 

 april 

 fallow 



(layer 

 from 

 17,7 to 



on 



cleared 

 land 



(layer 

 from 

 o to 



17.7 cm) 35 5 j.^) 17.7 cm) 17.7 cm) 17.7 cm) 3- 7 cm) 17.7 cm) 



3 years 

 lucerne 



soil 



(layer 



from o to 



17.7 cm) 



i.Unmanured 



2. Nitrogenous manuring 



3. Phosphate » 

 .( . Complete mineral » 



5. Sterilisation 



6. CUoroforming .... 



1. 00 

 1.06 

 1-49 

 2-74 

 2.95 

 1.71 



1. 00 

 0.85 



2.53 

 5.18 

 4.86 

 3.45 



1. 00 



0.93 

 1.32 

 3-56 

 4.04 



2.33 

 2.26 



\ 



are the causes of this increase in fertility ? In order to reply to this question 

 the writer carried out researches on the bacterial flora of the soils under 

 study and determined the chemical composition of the sterilised samples, 

 paying special account to two elements : phosphorus and nitrogen. Two 

 cultures were made, one on agar, the other on gelatine ; for each, peptonised 

 beef bouillon, diluted to o.ooi in the one case and in the other to o.oooi, 

 was utilised as the nutrient liquid. The calculation of the number of bac- 

 teria was made in Petri dishes in reference to one gram of absolutely dry 

 soil. These experiments were only made with April fallow tchernoziom 

 The results of these calculations, compiled in several tables, prove that 

 the bacterial flora of chloroformed and sterilised tchernoziom is incompar- 

 ably more numerous than the normal ; that it is more numerous in the ar- 

 able soil than in the layer below, and that in the case of sterilisation, it is 

 more numerous on agar than on gelatine. For instance, for the normal 

 samples of the arable layer in the culture on agar, with a dilution to o.ooi, 

 the number of bacteria before the experiments was 160 000 per one gram of 

 absolutely dr}^ soil ; a'ter the experiments, 167 000, or an insignificant in- 

 crease. In the soil chloroformed after the experiments the number of bac- 

 teria was 3 152 000 and in that sterilised it was 2 138 000. Considering 

 the case of the chloroforming of the tchernoziom, and laying stress on the 

 fact that it creates conditions in the soil which lead to a more energetic 

 multiplication of the bacteria, the writer believes that this action of the 

 chloroform must be the princi})al cause which, in chloroformed soils, leads to 

 the increased production of vegetable mass, because with the more intense 

 development of the bacterial flora those processes which enrich the soil in 

 fertilising elements, especially nitrogen and phosphorus, also intervene 

 with greater intensity. The enrichment of the soil in this latter element phos- 

 phorus, takes place, according to the writer, at the expense of its organic 



