NITRIFICATION IN ARABLE SOIL. 



3G5 



pare, tlie quantity of nitioiien iii)i>li('(l in tlie form of niannrc and the 

 amount nitrified wc; luive the following very instructive table: 



Quantities of nilric nifroaen found in the drainage water at different seasons of the year, 

 calculated to WO parts of nitrogen applied in the form of manure. 



Soil. 



Grig'iioii 



Wiinlrcrqiies. 

 ^larniilliat ... 

 Palbost 



Average 



Spring. Summer. 



14.15 

 10, 4G 

 9.50 

 7.90 



10.53 



7. CO 

 2.34 

 •2. 6-1 

 0.10 



3.01 



Kfj. 

 3.94 

 4.81 

 5. 04 

 5 12 



4.87 



"Winter. 



Kg. 

 1.55 

 1.24 



2.59 

 2.05 



1.85 



Whole 

 year. 



Kg. 



27. 28 

 18.85 

 20. 43 

 15.13 



20.43 



On an average one flftli of the nitrogen of manure was changed to 

 the form of nitric nitrogen during the year and either utilized by the 

 crops or lost. Of this total quantity 10 ]>er cent was found in the 

 drainage water in the spring, 5 per cent in autumn, and only 3 per cent 

 in summer. 



Ev^en if we assume that soils in place, mannred like the preceding, 

 furnish a proportion of nitrates as high as those obtained in tiiese 

 experiments, we tind that the amounts thus furnished are still insufti- 

 cient and that in order to obtain high yields farmers are obliged to use 

 nitrate of soda. 



A good crop of beets requires about 100 kg. of assimilable nitrogen 

 per hectare. All of the manured soils examined gave more than 100 

 kg. of nitrogen, and nitrification was sufiticiently active at the beginning, 

 as we have observed, to sustain a vigorous growth of beets. It must 

 be observed in this connection, however, that the beets were seeded in 

 April or May and attained full growth about the time of tlie heavy 

 rains of antuinn, so that omly the nitrates formed during the spring and 

 sunmier were utilized. Calculating the amounts thus obtained we have 

 the following figures: 



Nitrates available to a crop of beets during spring and summer. 



Kg. per hectare. 



Grisnon soil (m.iuured) , 118. 72 



Wardrecqnes (uiauured) 68. 94 



MarmiJhat (manured) 67. 44 



Palbost (manured) 52. 92 



Although these soils were surrounded by the most favorable condi- 

 tions, and nitrification in thein was undoubtedly much more active than 

 in soils in place, we find that three out of the four did not furnish, during 

 the period of growth, the amount of nitrates necessary for the produc- 

 tion of a good crop of beets. 



This is a singular situation and merits careful consideration. The 

 soils used in these e.xperiments contained from 1.5 to 2 parts per 1,000 

 of nitrogen, or jier hectare of 4,000 tons from 0,000 to 8,000 kg. of nitro- 



