362 EXPERIMENT STATION RECORD. 



t lie tube. At tlie besiniiiiig pots were used which contiiiued only 30 kg. 

 of soil, but these were soon replaced by others which held over 50 kg. 

 Ju most cases these pots were arranged in a trench, and protected from 

 direct radiation. Despite this precaution the soils were warmer and 

 drier than those in place. Althougli the elevation of temperature 

 favored nitritication and the drying impeded it, it is nottobesupi)osed 

 that these two opposite forces exactly couhterbalanced each other, but 

 it may be assumed that the results found did not vary much from those 

 which would be found iu soil in place in a climate warmer and a little 

 drier than that of Paris, 



This method of investigation has the advantages of re(iuiring little 

 space for installation, and of allowing almost iiuletijiite nudtiplication 

 of pots, with a large variety of wSoils; but while pots containing 50 kg. 

 of soil gave good average yields of small plants, such as rye grass, 

 clover, and eveu vetches, the larger plants — beets, wheat, and oats — did 

 not thrive well.in them. There was not sufficient room for the growth 

 of roots. To overcome this objection vegetation boxes were devised 

 which held as high as 5 tons of soil. 



The first investigations to which attention will be called were made 

 in pots, the last exclusively in the vegetation cases, which will be 

 described when the results obtained in them are discussed. 



(JOMPOSITION OF THE DRAINAGE WATERS OF MANURED AND 

 UNMANURED SOILS. 



The soils on which exiieriments were made were obtained from 4 

 different localities: From the experimental field of Grignon (Seine-et- 

 Oise) iu the vicinity of Paris; from Wardrecques on the boundary 

 between Pas-de-Calais and oS^ord; from Marmilhat and Palbost (Puy- 

 de-Dome) in central France; and from Blaringhem in the Department 

 of Nord. 



The soil of the experimental grounds of Grignon is light, permeable, 

 and sandy, and suffers more from drought than from excessive moisture. 

 It I'ests on coarse, rotten limestone, and is not drained, because it does 

 not need draining. The proportion of total nitrogen in this soil varies 

 from 1.5 to 2 parts per 1,000. The soil of Wardrecques (Pas-de-Calais) 

 is stronger than that of (irignon, being of excellent quality, but rests 

 on impermeable clay, and is much benefited by being drained. In 

 favorable seasons it. yields enormous crops of wheat. Its proportion of 

 nitrogen is the same as that of the Grignon soil. The soils of Marmilhat 

 and Palbost are more clayey, and do not attain their full value until 

 they are.drained. They are also poor in nitrogen. They were collected 

 in the i)lain known as the Limagne, which lies at the foot of the 

 mountains of Auvergne. They are very rich in organic matter, have 

 a characteristic black color, and generally contain over 2 parts per 

 1,000 of nitrogen. 



