1918.] EDITORIAL. 605 



of fertilizers with the result that nitrate of soda, which was for- 

 merly extensively used as a fertilizer for rice, has been almost aban- 

 doned for this purpose and sulphate of ammonia is now employed 

 as the principal source of nitrogen. Nitrate of soda was found to 

 leach from rice soils and to have little or no residual effect, while the 

 use of sulphate of ammonia was found highly advantageous. 



The growing of pineapples for canning has recently become one of 

 the large enterprises of the islands, the station having contributed 

 very largely to the development of the industry. After the discovery 

 of the injurious effect of a relatively high manganese content of the 

 soil on the growth of pineapples, investigations were continued from 

 which it was found that by spraying the plants four or five times 

 during the growing season with a solution of iron sulphate yellow- 

 ing was prevented and normal fruits produced. As a result of this 

 discovery, at least 5,000 acres of land that had been abandoned for 

 the cultivation of pineapples is being replanted to that crop. 



The station has been active in the introduction of forage plants and 

 improved varieties of grains, fruits, and vegetables, and in the pre- 

 vention of losses through the control of plant diseases and insect 

 pests. An experiment in cooperative marketing undertaken in 1913 

 in order to furnish an outlet for small quantities of produce of va- 

 rious kinds has proved quite successful, the sales increasing from 

 $26,500 in 1914 to over $121,000 in 1917, when the marketing division 

 was taken over by the Territory by which it is now maintained. Ex- 

 tension and demonstration work is being developed to some extent, 

 especially on the island of Maui, where a considerable number of 

 homesteaders are located. 



The Porto Kico Station, which is located at Mayaguez, has, since 

 its establishment, given much attention to soils and their manage- 

 ment. As many of the soils of the island are peculiar in their 

 acidity and iron and lime content, and require special management 

 to retain their fertility, experiments have been conducted in the 

 laboratory and field to determine their characteristics and require- 

 ments. In connection with these studies, attention has been given 

 to lime-induced chlorosis of cane and pineapples, and considerable 

 data have been accumulated regarding the nature of the diseases and 

 means for their control. 



Fertilizer investigations in connection with the different soil types 

 have been made for various crops. An extensive series of experi- 

 ments on the availability of different forms of phosphates for use 

 on Porto Kican soils is in progress, a preliminary report on some 

 phases of the work having been made recently. A survey of the bat 

 guano deposits in more than 100 caves has been completed and the 

 available supplies have been determined. A number of improved 



