272 



Bi;LLF;rix 275. 



Table XII. 



It will be seen from these records that germination was much poorer 

 in the steamed soil. 



From the first the growth was poorest in the steamed Soil No. i, both 

 of the unsteamed soils producing a better growth, while steamed Soil 

 No. 2 grew a better crop than either of the unsteamed soils. Fig. 77 

 shows a photograph of these baskets on April 5, about five weeks after 

 they were planted, in which they maintain this relation. This is the same 

 relative growth as that produced at this stage on these soils when planted 

 immediately after steaming. At harvest the same order of growth ob- 

 tained, which is contrary to the results given by the same soils when 

 planted immediately after steaming. However, owing to the lateness 

 of planting the crops were ripe in less than five months, which probably 

 accounts for the failure of Soil No. i more fully to recover from the in- 

 jurious effects of steaming. After the wheat was harvested millet was 

 planted without any further treatment of the soils, and Fig. 78 shows 

 that steamed vSoil No. i had produced by August 24 a better crop than 

 steamed Soil No. 2. It seems, therefore, merely a question of time 

 until this relation asserts itself after steaming. 



It will be noted that at the end of nine months the changes had not 

 taken place in these soils that had already occurred at the end of seven 

 months in the same soils when they were planted immediately after 

 steaming. This indicates that the growth of plants m soil serves to 

 hasten the recovery from the injurious effects of steaming. 



SUMMARY. 



Among the resvilts obtained by the experiments described in this paper 

 those that have not ])vvn brought to light by other experimenters are as 

 follows : 



I. Steaming the soil at two atmospheres pressure for two hours or 

 four hours reduces the nitrates of the soil to nitrites and to ammonia, but 

 most of the ammonia is formed from organic nitrogen. 



