In saline soils, the concentration of salt in the soil water can rise above 1.5% and prevent osmosis from moving water into the roots. It may cause water to move out of the root, thereby dehydrating the plant ( Poijakoff - Mayber and Gale, 1975). Soil salinization is often associated with sodic soil. For more details consult https://www.sciencdirect.com

More information is needed to answer this broad question well.

Is the sugarcane irrigated and if so what is the level of salt in the water?

Does the subsoil contain salts?

Is there higher ground nearby where water may be entering the soil and leaching salts down to your sugarcane?

What fertilisers are being used and do these contain salts?

Are you close to the ocean?

First what type of irrigation are you using. Second what is the EC of the irrigation water and the soil. Third do you have hard ban in your soil profile and how deep it is. Forth, do you have drainage system?. Do you have rainy seasons and how frequent and amount. Fifth, what is your soil type and what type of fertilizers are you applying. Last, do you add organic manure and at what rate?

Dear Jacob Simons sir, thanks well explained, area is far away from Ocean, but major problem is saline soil due to more irrigation.

This is due to the large quantities of irrigation water used to irrigate the crop, and therefore the process of accumulation of salt over time if the quality of irrigation water in which the content of salt allows the salts to accumulate.

Sugarcane (Saccharum spp. hybrids) juice quality is reduced by soil salinity. If the effect of salinity in commercial production is predictable, it will be possible to estimate juice quality in salt-affected fields prior to harvest. Variation in the effects of soil salinity on sugarcane juice quality in commercial production was assessed using 15-stalk samples harvested in 1992 and 1993 from a salt-affected commercial field of CP 70-321 sugarcane.

For further information please check the link

https://www.google.com/amp/s/www.researchgate.net/publication/248423050_Soil_salinity_and_sugarcane_juice_quality/amp

In addition to already pertinent mentioned answers - one solution is to identify salt resistant hybrids of sugarcane and test them under salinity condition. For this, you should have EC measurements in the soil and preferably other soil data analysis.

Depending on surface, type of soil, type of sugarcane culture, the amount and quality of water to be used in irrigation should be rationally calculated.

Two main reasons first is water source and second is fertilizers. You have to take care about these problems bcz this salinity it may effect on the juice quality on chemical extraction basis.