WATER SOILS. 54 ( .) 



if it was low to begin with, and the observed relations are in accord with the usual 

 immediate increased productive power of naked-fallow fields, if it is true that an 

 increase in the amounts of readily water-soluble salts in soils favor an increase of 

 yield." The concentration of the soluble salts in the upper layers of the soils was 

 more rapid in the unmulched than in the mulched soils, the concentration being 

 especially rapid in case of nitrates, chlorids, and sulphates. 



" In the case of the phosphates, silica, and bicarbonates, the distribution . . . was, 

 in some respects, the reverse of what occurred with the nitrates, chlorids, and sul- 

 phates; with these, the amounts decreased with great rapidity through the first 3 in. 

 and continued to decrease, only less rapidly to the bottom; with the phosphates and 

 the other two radicles, there was but a small decrease, if any, through the. first 3 in., 

 but a well marked tendency for the amounts to increase with the depth." 



The practical application of these results in soil management, especially as they 

 bear on the value of cultivation to make water-soluble plant food materials more 

 available and on the loss of plant food by surface drainage when the cultivation is 

 such as to cause the soluble salts to accumulate at the immediate surface is discussed. 



" Where the granular structure of the soil is feeble, as it is so often in the South, 

 heavy rains, and even very moderate ones, so puddle the immediate surface that the 

 water does not enter the soil readily but quickly flows to the lowest places, carrying 

 with it the soluble salts which have been concentrated at the surface, and, if the 

 fields are furrowed . . . much of the rainfall is liable to pass away in surface drain- 

 age and with it whatever of salts have been dissolved. Deeper plowing, which incor- 

 porates more of organic matter, and flat cultivation are two essential conditions which 

 will very materially lessen these bad effects." 



D — Absorption of water-soluble salts bij different soil types (pp. 114-168). — Investiga- 

 tions made on this subject between 1845 and 1865 are reviewed, and the results of 

 studies on the 8 type soils used in the investigations noted above are reported. 



In these investigations a complex solution, containing potassium 25 parts per mil- 

 lion, calcium 25, magnesium 10, nitric acid (N0 3 ) 40, phosphoric acid (HP0 4 ) 20, 

 sulphuric acid (S0 4 ) 40, and chlorin 30 parts, was employed. 



" In all cases the volume of the solution used was equal to five times the water-free 

 weight of the samples treated and generally 600 cc. of solution and 120 gm. of soil 

 were taken. Most of the observations were made with short periods of contact of 

 the solution with the soil, this being made sometimes by shaking in bottles and some- 

 times by percolation. . . . 



"The soils were examined for the amounts of water-soluble salts which could be 

 recovered from them by washing 3 minutes in distilled water, and the amounts so 

 recovered were added to the amounts which were added with the solution to the 

 duplicate samples of soil treated, and the absorption was taken as the difference 

 between the amounts remaining in the solution and those originally present, plus 

 those shown to be present in the soil before treatment. Only colorimetric methods 

 were used in determining the changes which occurred in the solution. . . . 



"The treatment of the samples consisted in weighing into stoppered bottles 120 gm. 

 of the dry soils and 4 gm. of carbon black, to decolorize the solutions. To each sam- 

 ple was then added 600 cc. of solution and vigorously shaken during 3 minutes; and 

 then allowed to stand 24 hours, but shaken, during 3 minutes, 10 times during that 

 interval." 



The results show "that very strong differences may exist in the absorptive power 

 of different soils and that, until the reverse is proven by careful observation to be 

 true, we must expect to find that soils having a high absorbing power are capable, 

 under favorable conditions, of giving larger yields than those having small absorb- 

 ing power, and there can be no question regarding the desirability of carrying out 

 suitable researches to establish what relation there may be between yields and the 



