AIR — WATER SOILS. 1029 



was found that plants could just exist with 0.45 per cent of the soluble 

 salts present, equivalent to about lo,000 lbs. per acre-foot, and this is 

 taken as the limit of plant production" in the preparation of these 

 charts and maps. 



"The results of these investigations show tbat the ultimate source of the alkali 

 is iu the sandstone, and particularly in the shale or slate rocks from which the soils 

 have been derived. Before irrigation was introduced the salts were present in 

 rather large amounts, but well distributed throughout the soil, and not in such large 

 quantities as to he injurious to crops. The injury is due entirely to ovcrirrigation, 

 to the translocation and local accumulation of salts by means of seepage waters, 

 and to the imperfect drainage facilities in the compact gumbo soils and the inability 

 of the soils to remove the excess of salts and of seepage waters. . . . The open 

 sandy lands, having better underdrainage, are not likely to be injured by a rise of 

 salts except from an excessive application of water or in the low places in the path 

 of the drainage system, especially when these are underlaid, as they are liable to 

 be, by the heavy gumbo subsoils. . . . The investigations show, further, the very 

 disturbing fact that the injury need not be due to a local application of water, but 

 to the injudicious application of large quantities of it in remote localities and on 

 neighboring farms. . . . 



"The investigations point clearly to . . . the necessity of great care in the appli- 

 cation of water in the methods of irrigation. This care must be exercised not only 

 for the land which is being irrigated, but for the adjoining lands on lower levels. . . . 



"Where the damage has been done, or where the conditions are so imminent that 

 ultimate ruin can be foreseen, the logical method of reclamation is in providing 

 adequate systems of drainage to carry off the excess of water and the accumulated 

 salts. ... It may be too soon yet to urge an extensive system of underdrainage 

 in the valley, but some small systems should certainly be introduced, if necessary 

 by cooperation, for an object lesson when it is considered necessary and timely to 

 protect against trouble or to reclaim lands already abandoned. . . . 



" It must not be assumed, however, that a thorough system of underdrainage 

 relieves one from exercising care and judgment in applying water to the land. 

 There is less immediate danger of ruining the land, to be sure, but there are two 

 things to be considered, namely, that an excessive use of water means just so much 

 loss to irrigation and so much less land which can be brought under the ditch, and 

 also that in the removal of these salts by the flow of the seepage waters out through 

 the drainage system large quantities of really valuable plant food are likely to be 

 removed from the soil. . . . By overirrigation and underdrainage we may remove 

 in a few years the very conditions which contribute to the wealth of the country in 

 the fertility of the soil. 



"In taking up new laud in the Yellowstone Valley the heavy gumbo soils should 

 be underdrained at the time the first irrigation waters are applied to the land. . . . 

 It is too late to wait until the damage has been done, for the accumulation of salts 

 themselves acts on the heavy gumbo soils and makes them more impervious to water 

 and harder subsequently to drain. Great care must be taken in the application of 

 water. . . . 



"The rise in the level of water in wells must be looked upon with uneasiness and 

 guarded against with great care." 



The advisability of cultivating such alkali-resisting crops as are 

 known, or of finding or breeding others, is discussed, but it is consid- 

 ered unfortunate "for a locality like the Yellowstone Valley, which is 

 originally free from alkali, to accept such conditions resulting from 

 their injudicious methods of irrigation and try to find crops which will 

 thrive upon lands which have been unnecessarily injured." 



