The Influence of the Age of Sugarcane on its Leaf-Nutrient (N-P-K) Content

Abstract

The age of sugarcane exerts a definite influence on the nutrient content of the sugarcane leaf. The effects of age on the leaf-nutrient (N-P-K) content were as follows: 1. There was a decrease in the nitrogen content of the leaf as the cane age increased. 2. The rate of decrease of nitrogen with age was greater for nonirrigated than for irrigated cane, being about 2 1/2 times as large for the former as for the latter during the first 7 months. 3. Leaf nitrogen declined more rapidly in ratoons than in plant crops. 4. There was no significant difference in rate of nitrogen decline for the varieties tested: B. 41227, M. 336, and P. R. 980. 5. The time of year the leaf samples were taken had no significant effect on the rate of leaf-nitrogen decline with the age of cane. 6. There was a marked decrease in leaf phosphorus with age of cane in nonirrigated cane up to 4 months, and no change from 4 to 6 months. 7. Irrigated cane decreased in leaf phosphorus, but not quite so rapidly as nonirrigated cane, a decrease apparent until about 9 months. After this the leaf phosphorus began to increase until a cane age of about 14 months, where it once again began decreasing. 8. Leaf potassium did not decrease with age throughout the whole growing period of the sugarcane. At first there was a decrease in leaf potassium with increasing age; however, there was a definite increase as the cane neared maturity. This increase began at about 5 1/2 months for nonirrigated and 15 months for irrigated cane. 9. A table of suggested correction factors for age of sampling is presented to assist workers engaged in foliar diagnosis of sugarcane.