WATER SOILS. 977 



the soil is drained by uumerous ditches and canals. Occasionally, 

 however, the saltwater breaks through the dikes, flooding the land and 

 making it unfit for cultivation for several years. 



In a study of the causes of the sterility thus produced the authors 

 found that when soils which had thus been flooded contained 0.5 per 

 cent of salt the growth of the ordinary field crops was seriously 

 retarded, but that with 0.2 per cent cereals grew normally. It was 

 further observed, however, that in soils of this region, termed saline aud 

 abandoned for that reason, sterility was sometimes due to a deficiency 

 of phosphoric acid and to slow nitrification resulting from imperfect 

 cultivation. 



On the composition of drainage waters, P.P. Deheuain {Gompt, 

 Rend., 120 {1895), No. 13, pp. 701-706). — An account is given of obser- 

 vations in the same line as those reviewed in previous numbers of the 

 Eecord.^ Comparing the results obtained in 1893, which was a year of 

 poor crops, with those obtained in 1894, a season of good crops, it was 

 found that drainage water was more abundant and much richer in 1893 

 than in 1894. The poverty of the waters in 1894 is attributed to the 

 vigor of the plants, which by means of their numerous roots com- 

 l)]etely assimilated the nitrates. The diminished amount of drainage 

 was due to the vigorous leaf growth, which returned to the atmos- 

 phere all of the water supplied by precipitation except during wet 

 l)eriods. Abundant drainage was obtained only during the winter, 

 while during the summer no water passed off in the drains. 



It is calculated that the wheat crop of 1894 per hectare contained 91 

 kg. of nitrogen and in 1893 only 44.2 kg., but in 1893 the soil lost 49.7 

 kg. of nitric nitrogen in the drainage water, while in 1894 the loss from 

 this source was insignificant. The total amount of nitrogen removed 

 from the soil in the good season of 1894 was therefore 91 kg., as against 

 93.9 kg. in the bad season of 1893. 



Further experiments by the author confirm previous conclusions that 

 fallow soils lose much more nitrogen in the drainage than those covered 

 with crops, and emphasize the importance of planting autumn catch 

 crops. 



The more important results obtained on 20 vegetation boxes left bare 

 and bearing various crops (grapes, sugar beets, wheat, and oats) are 

 given in the following table: 



Losses of nitric nitrogen in drainage waters. 



' E. S. R., 6, pp. 353, 491. 



