19 



100 pounds of acid phosphate per acre produced a yield of 900 pounds 

 of seed cotton, which was 50 per cent more than the yield of the same 

 varietj^of cotton in an unfertilized part of the same field. In another 

 case, on similar soil in Robertson County, 200 pounds of acid phos- 

 phate (14 per cent available phosphoric acid) caused an increase of 

 163 pounds of seed cotton per acre. On river-bottom soil in Robert- 

 son County an application of 140 pounds of cotton-seed meal with 

 140 pounds of acid phosphate per acre caused an increase in yield of 

 180 pounds of seed cotton per acre. In this localit}', as well as oh 

 alluvial soil in Wharton County, the application of 200 pounds per 

 acre of acid phosphate ha vino- 14 per cent of available phosphoric 

 acid did not increase the yield appreciably. 



The most striking results from the use of fertilizers were obtained 

 in the case of the work conducted in Washington County on heav}', 

 sandy river-bottom soil, which had been planted in cotton or corn for 

 at least fifteen years. The application of 200 pounds of acid phosphate 

 increased the yield about 20 per cent. The application of 300 pounds 

 of this fertilizer increased the yield in tlie neighborhood of 50 per 

 cent, not only in the case of improved varieties, but also in the case of 

 native cotton. The largest yields obtained an3'where during the season 

 \)y the Bureau of Entomology were in this location. One field of 

 native cotton, fertilized with 300 pounds of acid phosphate, yielded 

 at the rate of 1,712 pounds of seed cotton per acre. Two other plats 

 fertilized at the same rate yielded 1,632 and 1,437 pounds of seed 

 cotton per acre, respectively. Some of the plats fertilized with the 

 amount of acid phosphate that has been mentioned did not yield 

 nearly as high; nevertheless the average on the fertilized plats reached 

 in the neighborhood of 1,000 pounds of seed cotton per acre as against 

 an average yield of 527 pounds of seed cotton per acre in the case of 

 unfertilized plats. 



Upon black prairie soil in Karnes Count}', 200 pounds of acid phos- 

 phate per acre on the average, with several different varieties of cotton, 

 increased the yield con side rabh'. On 30 acres of early maturing 

 varieties and native cotton, the amount mentioned resulted in a net 

 gain of $5.65 per acre. Heavier applications of acid phosphate, at 

 400 and 500 pounds per acre, did not result in a net gain greater than 

 that mentioned in the application of 200 pounds. On the same planta- 

 tion an api:)lication of 300 pounds of a complete fertilizer, analyzing 

 8 per cent phosphoric acid, 2 per cent nitrogen, and 2 per cent potash, 

 caused an increase in the 3ueld per acre of 253 pounds of seed cotton, 

 resulting in a net gain per acre of $5.07.« 



A careful consideration of the subject of the fertilization of cotton 

 in Texas, by Prof. R. L. Bennett, will be found in Bulletin No. 75, 

 Texas Agricultural Experiment Station. 



21t> 



