48 Journal of Agricultural Research voi. v, no. i 



The top line in each case gives the results where no salts were applied. 

 Below this the figures are arranged according to the total quantity of 

 salt used, first i,ooo p. p. m., followed by 2,000, 4,000, 6,000, 8,000, and 

 10,000. It will be noted that with the chlorids and nitrates practically 

 no plants grew in the higher concentrations. Careful study of the table 

 is necessary to see the numerous complex relations that are brought out 

 between the various salts. The simple relations may be seen more 

 easily in figures 2 to 24, but by bringing together a large mass of data 

 in one table many relations can be found that could not be seen in the 

 diagrams. 



The average alkali of Utah contains a mixture of chlorids, sulphates, 

 and carbonates, with the carbonates usually present only in small quan- 

 tities. The practical alkali problem, therefore, is largely centered around 

 the sulphates and chlorids of sodium. An examination of Table XVI 

 does not seem to indicate that either of these salts has any great neu- 

 tralizing effect on the other. 



A general conclusion from this table might be that where alkali salts 

 are found together in the soil the toxic action of the combined salts is 

 only slightly less than the sum of the toxicities of the individual salts. 

 It may be that with other combinations of salts this conclusion would 

 not be justified. 



PRACTICAL LIMITS OF THIS PROBLEM 



The practical problem of this entire study is to determine the quan- 

 tity of various alkali salts necessary in the soil to reduce the growth of 

 crops beyond the point of profitable production. Under the conditions 

 of dry farming there is no practicable way of removing excessive soluble 

 salts; hence, if salts are found in these soils in quantities prohibiting 

 crop growth, the soils are valueless for agriculture. On the other hand, 

 soils that are susceptible of irrigation and drainage may be reclaimed 

 by the leaching out of the alkali. In any soil, however, where there is 

 a likelihood of alkali injury it is very important, in order to be able to 

 judge the value of a soil, to know exactly how much of a given salt 

 is necessary to injure crops. The literature on the subject up to the 

 present is somewhat conflicting and lacks the definiteness that would 

 be desirable. 



There are so many factors entering into the toxicity of alkali that it 

 is difficult to assign definite toxic limits. For example, an analysis 

 might show a soil to contain a given percentage of salt when in reality 

 the greater part of the salt might be in a crystallized form at the sur- 

 face, where it would do no harm until dissolved and washed back- into 

 the soil. It is the salt in solution that does the real injury. The wetness 

 of the soil, its texture, the presence of neutralizing substances, and a 

 number of other factors all alter the toxicity of soluble salts, which 



