8 BULLETIN 9502, U. S. DEPARTMENT OF AGRICULTURE. 
ordinary conditions this is about all that is necessary to know in 
order to forecast the probable difficulty that will be encountered 
in bringing the land to a condition for cultivation subsequent to 
drainage. 
Surface accumulations of the alkali salts should not be taken as 
conclusive evidence of a case of extreme alkali trouble, for when 
the soil water rises to such a height that the surface of the ground 
is kept moist by the capillary water, high evaporation results, and 
as only relatively pure water passes off in this manner, it follows 
that the salts are left at the surface. If this process continue for 
sufficient time, heavy incrustations of salt may form on the ground 
surface irrespective of whether the soil water is highly or slightly 
alkaline, though the higher the percentage of alkali in the soil water 
the more rapid the accumulation of the salts by evaporation. Con- 
sequently, the more alkaline the soil water the greater the necessity 
for immediate relief by drainage. The necessity of the drainage of 
those shale lands that have become water-logged is shown from a study 
of the following tables. Table I contains the results of analyses of 
soil water as discharged from 10 newly installed drainage systems 
on tracts at one time under cultivation. Samples A and B in Table 
II are two samples of seepage water through shale from a canal the 
first season after construction. Sample C in Table II is seepage 
water in a valley in the bad-land topography shown in Plate IV. 
TABLE I.—Andalyses of drainage waters from systems in shales. 
(Tracts at some time under cultivation.) 
Milligrams per liter (parts per 1,000,000). 
1914 1914 1914, | 1914, | 1915, | 1915, | 1916, | 1916 
Substance. a we Apr. Apr. June May | Mar. | Mar. Feb. | Feb. 
Dice | nether fe 27. 11, 8S SON Ze steal ee 
A. B. CG 1D). EB. F. G. H. I. J. 
Ions. ; 
Sulphuric/acid (S04). -2-2-2.-..-- 2,542 | 8,566 | 24,932/25,382 [3,132 |13,320)10, 508) 5,500] 6,372)20, 470 
Carhonieacidi(tOs) heseenesee ee nese eee Pee eee 12 1557) bee ai) errs oy Legis Set A Se te 50 
Bicarboniec acid (HCOs3)......-.-.- 467 556 583] 728 348 632} 513) 427) 861) 688 
INitmicracidv@N@s) ess) 2. eeee 14.2} 398 1,253] 982 200 832} 286] 443) 4,861] 7,614 
Chiloninei(Cl) soe is ae 41 172 294] 305 156 490} 262) 3878] 232| 428 
Caleiamy(Ca re sees ee ee 517 428.5 427, 452 505.5} 425) . 405) 453) 602) 492 
Maenesium (Mic)\pse28 ep ee eee 381 | 1,016 2,754) 3,333 362.5) 878) 600) 570} 1,315] 2,746 
SOeitiran (NE) S35 cadosseseesesess Tat |) 25 GTS 7) 15 1A}) Ge ilieds} 540 | 5,094} 3,901) 1,606) 2,151) 7, 442 
Mota soe: sessment et: 4, 073. 2|13, 293. 21° 37, 378137, 375. 215,244 |21,671!16, 475) 9,377/16, 394/39, 930 
| 
Hypothetical combinations. 
Sodium carbonate GNiasCOs)e 5.22 pence ll ben co wce ol cere oleae al ee ee rs | cere | nce ee el ee re | eee 
Magnesium sulphate (MgSOq)..-| 1,886 | 5,030 | 13,633/16,499 |1,795 | 4,346) 2,970) 2,822) 6,510/13,593 
Sodium nitrate (NaNO3).......- 19.2} 545.6) 1,718) 1,346 274 1,140} 392) 607] 6, 664/10, 438 
Sodium chlorid (NaCl).......-.- 68 283. 5 485} 503 257 809} 432) 623) 382) 706 
Sodium sulphate (NaySO4)------ 244 | 5,860.5} 19,975]17,346 |1,127 |13, 798/11, 196) 3,695] 609/13, 287 
Calcium sulphate (CaSOq)....-..-| 1,236 835.5 773) 689 |1,329 739} 803] 1,063] 1,085} 904 
Calcium bicarbonate (Ca(HCOs3)2)} 620 738. 1 774| 967 462 839] 682] 567] 1,144) 914 
Caleim carbonate |(Ca@ 3): s2ee|eeea4s-e| een - 20 DDS Dice Ses c3] cee ea Pie ea Geet leas en 
Miptelliaivn yuestae Weal tea he | 4,073. 2/13, 293. 2] 37,378|37,375. 2/5, 244 21, 671)16, 475] 9, 377/16, 394]39, 930 
