WATER SOILS. 631 



on the basis of dry weight of soil, a table being given by which per- 

 centages calculated on the fresh weight may be converted into those 

 calculated on the dry weight. 



Tables and diagrams show the daily variation in the moisture content 

 of the soil during April to September in early truck land at Mardela 

 Springs, Maryland; blue grass (Trenton limestone) land at Lexington, 

 Kentucky; cotton land (Red Hill formation) at St. Matthews, South 

 Carolina; sandy cretaceous cotton land at Union Springs, Alabama; 

 sandy cretaceous cotton land at Fort Deposit, Alabama; black creta- 

 ceous prairie at Macon, Mississippi; black clay of the Mississippi bot- 

 tom at Greenville, Mississippi ; black waxy soil at Paris, Texas, and 

 prairie land at Colby, Kansas. 



" Curves illustrate in a graphic way the conditions in several soils 

 during a period of quite marked drought, during which crops suffered, 

 in the season of 1890." These and other data in the case of some of the 

 soils which have been studied for some time under different weather 

 conditions have been used as a basis for approximately establishing 

 lines of excessive moisture and of drought in the soils. 



Researches on the drainage waters of bare and cultivated 

 soils, P. P. Deherain (Ann. Agron., 23 (1897). Xo. 6, pp. 241-267).— 

 This is a summary of observations on the vegetation boxes at G-rignon 

 during 5 years. 1 The results clearly demonstrate that the quantity of 

 nitrates removed by the drainage water from bare soils is very much 

 greater than that removed from soils covered with a crop, and this 

 discrepancy is not in every case entirely accounted for by the amount 

 of nitrates utilized by the plant. 



From the data obtained in experiments with wheat, it is estimated 

 that the amount of nitric nitrogen utilized by the crop and removed in 

 the drainage water was only 94 kg., while the amount of nitric nitrogen 

 found in the drainage water from a check plat of bare soil was 200 kg. 

 The wide discrepancy in this case may be partially accounted for by 

 the fact that during a part of the growing season of the wheat the 

 moisture was not sufficient for the needs of the crop and for active 

 nitrification in the soil. In experiments with corn, during the growing 

 season in which the rainfall was abundant, the amount of nitric nitrogen 

 utilized by the crop and found in the drainage water was 197 kg., as 

 compared with 200 kg. found in the drainage water of bare soils. 



These results show in general that the soils experimented on are 

 capable, with a sufficient supply of moisture, of furnishing all the 

 nitrates required by the largest crops, and indicate that if provision 

 were made for a sufficient supply of irrigation water at all periods of 

 the growing season, nitrification would be so promoted that much 

 smaller applications of nitrogenous fertilizers would be required. 



1 For abstracts of previous work in this line see E. 8. R v 6, p. 977. 



