AbstractA variety-fertilizer experiment using four varieties at seven fertilizer levels was carried on for a plant sugarcane and four ratoons. The major results were: 1. Nitrogen gave the highest yield increases in hundredweights of 96° available sugar per acre. 2. Phosphate fertilizers did not increase the yields of sugar. 3. Potassium fertilizers did increase the yields of sugar per acre. 4. The application of nitrogen and phosphorus did not influence sucrose concentrations in the cane. The omission of potassium did decrease the sucrose content of the cane significantly. 5. Variety P.R. 903 gave the highest yields of sugar per acre as compared with P.O.J. 2878, M. 275, and M. 317. The yields of M. 317 and P.O.J. 2878 were about equal, and M. 275 gave the lowest yields. 6. The varieties maintained their relative yielding power when tested at various fertilizer levels. Except for the no-fertilizer level, P.R. 903 maintained its significant lead in yield at all levels of fertilizer application. There was no significant interaction between varieties and fertilizers. 7. The reductions in yields from the omission of a fertilizer element for the mean of five crops were 33, 3, and 9 percent for nitrogen, phosphorus, and potassium, respectively. 8. Analysis of leaf samples revealed that corrections must be made for rainfall to prevent a yearly variation in the data. When corrected for rainfall variations, values of 1.40 percent nitrogen (dry weight of the leaf) or below were associated with low cane yields, and values of 1.60 percent or over with high yields. For phosphorus, values above 0.17 percent phosphorus in the leaf at a cane age of 3 months may be regarded as indicating no appreciable need for phosphate fertilizers. Potassium values of 1.70 percent potassium in the leaf or less indicate a need for potash, and 1.90 percent or greater, none.
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