14 



In many cases experiments during the past ten years, on soils of diffe- 

 rent character in this portion of the state, have shown increases in yield 

 all the way from two to five or six times, by the application of potash fer- 

 tilizers only. " 



To what extent these conclusions will hold true in the case of the 

 Porto Rican marshes, remains to be seen. They give, however, some ind- 

 ications as to what field experiments are apt to give good results. The 

 first and paramount necessity in the reclamation of all marsh lands, 

 is sufficient drainage, and this is especially so in the marsh soils of Porto 

 Rico. The reasons for this latter statement will be fully explained in the 

 following chapters of this bulletin. As far as fertilization goes, we may 

 expect, on the basis of the studies reported and of the analyses of the 

 Porto Rican marsh soils made in this laboratory, that they will be 

 benefitted by the application of potash and phosphoric fertilizers, but 

 that nitrogen may not have much effect, owing to its presence in large 

 amounts in the 'soils themselves. It is, however, possible that the humus 

 nitrogen may not be so available as it has been found to be in other 

 countries. The only way to decide the question of fertilizer requirements 

 is by actual experiments in the field where the three elements are applied 

 alone or in mixtures of various proportions, in different forms, and in 

 varying: quantities. Only such a practical test will disclose what fertilizers 

 wall bring the greatest pecuniary profits. 



The administrator who was in charge of the Tiburones lands last 

 year, made a small test with potassium sulfate alone, applying it in some 

 of the worst lands. The cane soon improved visibly, and the result of 

 this small test demonstrates the value of such experiments. However. 

 in order to get results of permanent value, il will be neeessarv to n 

 the experiments in a systematic way so that tbe influences of other fac- 

 tors than fertilizers may be excluded as much as is practicable. 



THE SALT CONTENT OF THE MARSH SOILS, 

 AND ITS RELATION TO THE PRODUCTION <>F CANE. 



In an ordinary marsh, drainage is provided with the main object 

 of removing the surplus water, and of reducing the moisture to such an 

 extent that the physical, chemical, and biological processes, without which 

 the soil cannot support the growth of cultivated plants, may take place 

 normally. But in two other large classes of soils, namely, the marine saline 

 lands, and the alkali lands, the establishment of a good drainage system 

 is necessary for another most important reason. While these two soil 

 groups show certain differences in their nature and origin, the soluble 

 salts which arc characteristic of both, are qualitatively identical, and the 

 object of reclamation is essentially the same in both eases. The dominanl 

 feature of these soils is the comparatively high quantity of soluble salts 



