3.2. Nutrient index of different sugarcane zones
The NI ranking was used to assess the long-term sugarcane mono-cropping impact on nutrient pattern changes (Table 4). The NI of SOC altered from medium to low category (<1.67) in CZ and WZ, but EZ maintained at medium level (1.69). Lower NI (<1.67) of Nawas recorded entire the cane producing zones under the study, being the highest was in CZ (1.04) than that of EZ and WZ (1.00). NI of Pa and Ka was falls under medium category (1.67-2.33) in CZ and WZ, whereas lower level was existed in EZ. The medium NI category of Sa was maintained only in WZ but EZ (1.51) and CZ (1.38) showed <1.67. The NI of Zn was recorded in medium level which ranged between 1.67−2.33 in EZ and CZ, whereas WZ soils had lower NI levels of Zn (1.66). The NI level of Cu, Fe and Mn were highest (>2.33) across the cane producing zones of Uttar Pradesh, except NI of Fe was maintained at medium level in WZ. Overall, the higher mean NI value was observed in CZ (2.19) followed by EZ (1.98) and WZ (1.97).