860 



EXPERIMENT STATION RECORD. 



Fertilizer experiments, 1897-1905, C. F. Eckart (Hawaiian Sugar Planters' 

 Sta., Div. Agr. and Chem. Bid. 15, pp. 57, dgmx. 10). — These experiments, which have 

 been previously noted (E. S. R., 15, p. 960), are conducted on 20 plats, including 2 

 check plats. 



Lahaina and Rose Bamboo sugar cane are grown, 10 plats being devoted to each 

 variety, and the essential plant-food elements, furnished either singly or in combi- 

 nation, are each applied at the rate of 100 lbs. per acre. Analyses of the station soil 

 and of average soils on the 4 principal islands are reported. The data secured during 

 the 8 years are tabulated in detail and discussed. 



The results with respect to purity of juice for both varieties show that the highest 

 purity, 90.69 per cent, was obtained on the unfertilized plats, and the lowest, 88.29 

 per cent, on the plats receiving a complete application with the nitrogen in the form 

 of sulphate of ammonia. The highest sucrose content, 18.26 per cent, was also secured 

 on the unfertilized plats, and the lowest, 16.40 per cent, on the plats given a com- 

 plete fertilizer with the nitrogen in the form of dried blood. The average yields of 

 sugar for the 2 varieties, together with the percentage of gain or loss from fertilization, 

 are given in the following table: 



Comparison of plat yields by four-year periods. 



Fertilization. 



Yields of sugar per acre. 



First 

 period. 



Second 

 period. 



Differ- 

 ence for 

 second 

 period. 



Gain or loss from 

 fertilization. 



First 

 period. 



Second 

 period. 



No fertilizer 



Nitrogen 



Phosphoric acid 



Potash 



Nitrogen and phosphoric acid 



Nitrogen and potash 



Complete fertilizer 



Pounds. 

 21, 458 

 25, 047 



•22, 241 

 24, 593 

 26, 464 

 29, 119 

 27, 379 



Pounds. 



15, 974 

 19, 348 

 13, 633 

 14, 182 

 20, 533 

 21, 478 

 23, 438 



Per cent. 

 25. 6 



22.8 

 38.7 

 42.3 

 22.4 

 26.2 

 14.4 



Per cent. 



Per cent. 



+16.7 

 + 3.6 

 +14.6 

 +23. 3 



+35. 7 

 +27. 6 



+21.1 

 -14.7 

 -11.2 

 +28. 5 

 +34.5 

 +46. 2 



These experiments have shown that lands capable of producing 11 tons of sugar 

 per acre without fertilization, may be profitably fertilized under favorable climatic 

 conditions and a sufficient water supply. Mixed fertilizers produced a greater per- 

 centage of gain as the soils suffered a gradual exhaustion. Rose Bamboo cane 

 seemed to require a larger supply of phosphoric acid in the soil than Lahaina, while 

 Lahaina responded more to an increased supply of potash than Rose Bamboo. Both 

 varieties showed considerable gain from the use of nitrogen, in which the soil was 

 below the average for the islands. 



On land much richer in phosphoric acid than the average soil, Rose Bamboo gave 

 larger yields when phosphoric acid and nitrogen were applied together than when 

 nitrogen was given alone, but Lahaina under the same conditions gave about equal 

 yields. On soil containing about the same quantities of potash as an average island 

 soil both varieties gave increased yields when this element was applied with nitro- 

 gen. It was also found that the separate use of phosphoric acid in soluble forms on 

 soil already rich in this element may result in a loss of sugar, and that apparently 

 the chances of loss are greater with Lahaina than with Rose Bamboo, where both 

 make an equally thrifty growth under normal conditions. 



Separate applications of potassium sulphate to lands under cane also sometimes 

 decrease the yields of cane, and the danger of loss seems greater with Lahaina than 

 with Rose Bamboo. A particular element given alone may produce negative results, 

 but it may be very effective in increasing the yields when applied with some other 

 element. The unfertilized areas produced the purest juice, and, in general, the 



