40 



the characteristic black surface soil and the white calcareous subsoil. 

 Here, according to Mr. Crawley, the water is very near the surface so 

 that the cane roots are in contact with it. 



We find that in samples Nos. 1 to 3 the salt content is exceedingly 

 high, and so far only typical salt plants grow in these soils'. 



Nos. 4 and 5 are interesting samples inasmuch as they bear out our 

 conclusion arrived at above, that the cane will in marsh lands stand much 

 less salt when it is growing in standing water than when its roots are not 

 in contact with the ground water. In fact, the cane at that place is not 

 growing well. 



RECLAMATION OP THE MARSHES. 



In the preceding chapters we have ascertained the trouble that 

 prevents the cane from growing normally in these salt marshes and have 

 found out under which conditions it will grow well. We now come to 

 the question as to how these conditions may in practice be arrived at 

 with the least possible expense. The first necessity is, as we have seen, 

 the lowering of the water level. This would be indispensable, even if 

 the water did not contain salt, since, as is well known, cane is a plant 

 that requires excellent drainage. However, as the water in this marsh, 

 is not fresh water, but, on the contrary, highly charged with salts, drainage 

 becomes absolutely imperative. We have seen that around the center of 

 the swamp, about stations 3 and 4 of Series 2, the salt content is exceed- 

 ingly high, and the counteracting sulfates are low. By dropping the water 

 level sufficiently the trouble can be remedied, and regular floods which at 

 present are a great danger to the cane in wet weather, will thus be 

 avoided. After good drainage has been provided the excess of salt must 

 be washed out, by the natural rainfall, and, if necessary, by the aid of 

 irrigation, until the concentration of the salts falls below the danger 

 point as indicated by the results of our investigations. But before an 

 attempt is made to leach out the salts, an excellent drainage system must 

 first be installed. Unless this be done, always forcing the water to move 

 in a downward direction, it will dissolve the salts out of the lower soil 

 strata, then rise by capillary action, and on evaporation will leave more 

 salts in the surface layer than there were before. It will be well to quote 

 Maxwell's own words in this connection C 1 ). "The salt content of the 

 soil and its action upon the growing crop can be modified by the amount 

 and quality of the water used in irrigation. 'Sweet' water can carry the 

 salt down out of reach of the cane roots, but if there is no outlet for the 

 water through the subsoil, it will come up again by evaporation to the 

 surface, bringing with it a greater excess of salt to deposit near the 

 roots. ' ' 



(1). O. E -S. Bull. 90, p. 17. 



