54 BULLETIN 699, U. S. DEPARTMENT OF AGRICULTURE. 



The results given in Table XXVIII indicate strongly that medium 

 applications of phosphate, either soluble or relatively insoluble, pro- 

 duced appreciable increases in the yield of sugar cane. The yields 

 on the whole were slightly in favor of the acidulated phosphates, but 

 the average yield of the plot treated with a combination of basic 

 slag and " basal mixture " exceeded those of all the other plots. 

 The plot treated with dissolved bone black alone gave the next high- 

 est yield, followed by the plots receiving mixtures of the acidulated 

 phosphates (dissolved bone black and acid phosphate) and " basal 

 mixtiu-e." The yield of the floats-basal mixture plot, however, was 

 so close to that of the latter two that the difference is well within 

 experimental error. When applied alone. South Carolina " floats " 

 and bone meal apparently gave about equal results, the yields being 

 greater than that of the acid-phosphate (alone) plot. 



In two out of the three experiments of the Louisiana station here 

 cited, the applications of raw rock were so light and the evidence 

 points so strongly to the lack of uniformity in the experiment fields 

 that the results have little value. In the third experiment, however, 

 where the phosphates were applied more liberally the increased 

 yields of sugar cane obtained from the insoluble-phosphate treat- 

 ments compared favorably with those from the soluble-phosphate 

 plots. 



MAINE. 



Owing to the limited data presented and their short duration 

 (from one to two years), six^ of the nine experiments with raw rock 

 phosphate conducted by the Maine Experiment Station are not con- 

 sidered in this paper. 



In 1895 ' the Maine station published the results of two field ex- 

 periments with various forms of phosphoric acid. One was con- 

 ducted for nine years and the other for seven years. 



The first experiment was conducted on a 2-acre field which was 

 divided into 36 plots containing one-twentieth acre each. The soil 

 of this field was a clay loam and said to be quite uniform throughout. 

 Before the sod was broken for the experiment in 1885 the field had 

 grown three heavy crops of grass, previously to which it had received 

 a liberal application of stable manure and unleached wood ashes. 

 In 1885, without any further addition of fertilizer, the field produced 

 a crop of barley. 



Fertilizers were applied only five times during the nine years of 

 this experiment, no applications being made in 1888, 1890, 1891, and 



1 Me. Agr. Expt. Sta., Ann. Repts. for 1888, pp. 64-66 (1889) ; 1889, pp. 140-143 

 (1890); 1890 (1891); 1891 (1892). 

 *Me. Agr. Expt. Sta. Ann. Rept. for 1894 (1895). 



