1912] Lipman: Bacteria in Soils of Arid Begions 11 



give the quantitative results as they are given for ammonification 

 in table I. The plus sign represents nitrate formation and the 

 minus sign the absence thereof. The numbers of the soils are 

 referred again to the descriptions above given. 



TABLE II 



Nitrification in Soil Columns 



Soil No. 1 2 3 4 5 6 7 8 9 10 11 



1st ft. + + + + + + + ___ + 



2na ft. + + + + + — + — __ + 



3rd ft. + + + + + _ + ___ + 



4th ft. + + + + + _ + ___ + 



5th ft. + + + + + _____ + 



6th ft. trace + __ + _____-|_ 



7th ft. ___ — ______ + 



8th ft. __________ + 



9th ft. — — — — — — _ _ _ 



10th ft. — — — — — ___ 



11th ft. — — — — _ _ _ _ 



12th ft. — — — — — _ _ _ 



From the data in table II we see again a striking resemblance 

 between nitrification in the soil depths and ammonification in 

 the same. All the alluvial soils in particular show very uniform 

 nitrate formation. The latter seems to be as much inhibited 

 in soil No. 1 by the hardpan layer as is ammonification. In 

 soils 2, 3, 4, and 5, as well as 7, we find a general tendency for 

 nitrates to be formed in the first five feet and then an enfeebled 

 power of nitrate formation, in some cases for one foot and in 

 other cases a total loss of that power. In nearly all cases these 

 run parallel with a similar decrease in ammonia formation, but 

 it seems that nitrate formation is more seriously hampered by 

 the conditions which curtail ammonia formation and particularly, 

 it appears, by the lack of oxygen in the lower layers of the soil. 

 This is an account, therefore, of the first case which has come to 

 my notice of nitrification at any depths below two or three feet 

 in the soil, and shows a marked difference in itself between soils 

 formed and existing under humid and those formed and exist- 

 ing under arid conditions. Nitrogen therefore is available in 



