NITRIFICATION IN ARABLE SOIL. 



363 



The (luaiitities of diaiii;ij;e water obtained tVoiii these soils, maiiuied 

 and unmamued, ealculated to millimeters, are shown in the following- 

 table : 



Drainaijc water J'lvin manured atid loinuduircd soils witltout revelation, March, 1S91. to 



Mare It, hS9-^^. 



Kind of soil. 



Exi>orjmf'iital field of (rrignoii 

 Wiiidi <i I] lies ( Piis-de-Calais) . . 



Mariiiilhat (Piiy-de-Doiue) 



Palbost (Puy-de-Doiiic) 



Manured. Uumaniired. 



Mm. 

 315.3 

 259. (i 

 332. 7 

 240.0 



Mm. 



■ill. 3 

 25 1 . 3 

 327. 7 

 373. 



Difl'erence. 



Mm. 

 +38. 

 + 8.3 

 + 5.0 

 -33.8 



The variations, favoring the manured soil in one case as much as 

 they do the unmanured soil in another, indicate that the addition of 

 barnyard manure did not exert an appreciable intluence on the power 

 of the soils to retain water. 



The unmanured soils gave, from March, 1S91, to March, 1892, the fol- 

 lowing (luantities of nitric nitrogen. 



Xitric nitrogen in drainage water. 



Grignon : Kg. per hectare. 



A without maimre ; in grass since 1879 78. 52 



B cultivated ; well uiaimred 115. 95 



C cultivated ; without manure since 1875 74. 70 



Wardrecques 73. 80 



Blaringliera 112. 60 



Marniiihat t)2. 06 



Palbost 63. 44 



These figures are much higher than tnose obtained at Rothamsted. 

 Warington found, in 1877 to IS80, 44 kg. of nitric nitrogen per hectare, 

 annually, while our soils have furnished on an average 83.01 kg. 

 We point out below the probable cause of this divergence. If the 

 preceding figures are carefnlly compared it will be seen that light soils, 

 such as that of Grignon, enriched by previous manuring, give a much 

 greater (piantity of nitrates than similar soils remaining for a long 

 time without fertilizers. It will be observed, on tlie other hand, that 

 in spite of the lack of recent manuring the organic matter of the soil 

 in plat C, which had remained without fertilizers since 1875, still fur- 

 nished considerable (juautities of nitrates, a little more than that 

 observed in Wardrec(iues and Limagiie soils, but appreciably less than 

 that found in the Blaringhem soil. In order to arrive at the extent 

 of nitrification of the nitrogen of the manure, the surface area of the soil 

 re]>resented in two of the above experiments, one without manure and 

 the other with 1 kg. of good barnyard manure, was determined, and 

 from this the amount of barnyard manure ai)plied per hectare was cal- 



