Much like when we can tell a mango or a plum is ripe enough to be eaten, there is also a way to tell when the sugar cane is mature enough to be harvested and taken to the mill for sugar extraction. Sugar cane maturity is determined by the variety type, the plant age in months, the climatic conditions and husbandry care given to the plant.
Some visual symptoms that can tell the maturity of the sugar cane are the yellowing or drying up of leaves, the plant core structure becomes weak, the quantity of leaves decrease to approximately 5 and the top internodes are notably shorter than the internodes of the rest of the stalk.
The most important parameters that tell the maturity of the sugar cane are the Brix, the sucrose percentage or POL, and apparent purity. Unlike POL, Brix can be measured in the field using a refracatometer.
- Brix del Jugo : Los Brix del Jugo se refieren al contenido de sólidos solubles totales presentes en el jugo, expresados como porcentaje.Brix Juice refer to the contents of total soluble solids in the juice, expressed as a percentage. Los Brix incluyen a los azúcares ya compuestos que no son azúcares. Brix compounds include the sugars and non-sugar. Los Brix pueden ser medidos en el campo, en la misma plantación, utilizando un refractómetro manual para Brix o HR Brix. Para esto se perforan varias plantas en el campo y se colecta su jugo para formar una muestra compuesta que será analizada.
In order to determine if a cane field is mature enough to be harvested it is important to calculate the Maturity Index of that field that is simply the average relationship of the Brix reading of the Superior and inferior part of the stalks of that field.
Four easy steps to determine Maturity Index of a cane field:
1. Select five points in the field, one point in each corner (maintaining 5-7 rows as borders) and one point in the center of the field.
2. At each point select 10 stalks at random. With a small tool drill each stalk at the second inferior internode (BI) and at the seventh left internode of the superior part (BS) of the plant to extract the juice of the cane.
3. With each drill place some of the juice on the refractometer, read and take note of the numbers.
4. Calculate the Maturity Index: ((BS/BI x 100) + each sample taken)/50
If the maturity index is 85% or more the cane field is ready for harvest. If the IM is greater than 100% the sugar cane is over-mature and enters in a state of deterioration where accumulated sucrose starts to decompose. It is not important to harvest cane that is mature only, under mature or over mature cane can pose problems to the quality and quantity of sugar extracted at the mill.