788 EXPERIMENT STATION RECOKD. [Vol.35 



the maximum, minim.um, and mean for the mulched section were all much 

 higher than for the clean cultivated section. This was especially true in the 

 earlier part of the season when the mulch was heavy. Later on, the straw 

 became somewhat dissipated, and the moisture was not retained as well as 

 earlier in the season. One considerable factor in the higher average under the 

 mulch was that all of the ground was uniformly moist ; while in the case of 

 furrow irrigation the ground in the tree rows received very little benefit from 

 irrigation." 



Text-book of land drainage, J. A. Jeffery {New York: The Macmillan Co., 

 1916, pp. XX-{-256, figs. 95). — This book, prepared mainly for the practical 

 farmer, represents an attempt " to put into simple and concise terms the funda- 

 mentals of our knowledge concerning the relation of water to agriculture and 

 of the relation of drainage to soil water." It contains the following chapters : 

 Characteristics of soils, physical interrelations in soils, humid areas and their 

 reclamation, general drainage information, leveling, laying out a drain or sys- 

 tem, construction, other conditions and problems, the hose level, using the 

 hose level without leveling rods, drainage indications, drainage and the ground- 

 water supply, drainage and climate, and drainage laws. 



An appendix describes 18 experiments prepared to demonstrate some of the 

 more important facts concerning soil conditions and drainage. 



The drainage of white land and other wet lands in Oregon, W. L. Powers 

 and T, A. H. Teetee {Oregon Sta. Bui. 137 {1916), pp. 80, figs. ^S).— "This 

 bulletin describes experiments to determine the most suitable depth, distance 

 apart, and size for field drains in white land, and also gives information regard- 

 ing the drainage situation in Oregon in general. There is in the State a great 

 variety of wet lands of which three classes [predominate], namely, white land, 

 marsh land, and alkali land. Drainage of much of this wet area appears to be 

 feasible, as good quantities of plant food and friable layers have been found 

 therein. . . . 



" Studies of subsoil and ground water in white land generally show a friable 

 streak at 33 to 36 in. depth and show also that tile placed in these areas have 

 lowered the water table most promptly. The water table is lowered for 25 to 

 30 ft. back from the tile within 24 hours after saturation. 



" A depth of 33 to 36 in. has been found most effective for lateral drains in 

 typical white land, while deeper drains are desirable in the less retentive areas. 

 An interval of 60 to 66 ft. between laterals affords the most practical drainage 

 for typical white land under present conditions, and this distance may be 

 increased in less retentive phases of this soil. 



" Measurements of outflow indicate that main drains should have a capacity 

 of i acre-inch run-off to the acre in 24 hours for areas up to 40 acres nnd i in. 

 for larger fields. The total and percentage run-off in the Willamette Valley is 

 large. 



" Since drainage is costly and white land subsurface is retentive, farm opera- 

 tions should aim to aid water in entering the tile. When drained fields are In 

 clover a larger outflow from tile and less surface water have been observed, and 

 the structure and fertility of the land gradually improves. 



" Reports from farmers having over 100 miles of tile in operation in the 

 white land and other wet land in the valley show that tiling has generally been 

 successful. The tendency is toward larger tile in place of small open ditches. 

 A combination of tile with a surface run is good practice. Nature has deter- 

 mined the general location of ditches, and the size of the natural channel is an 

 index to the reqiiired capacity. The grade should be low enough to receive the 

 discharge from all laterals." 



Important features of the state drainage law are also noted. 



