Abstract
Sugarcane mono-sequencing is one of the prominent systems of Uttar
Pradesh but wide variations in cane yields are the main cause of concern
across the cane producing zones. Hence, this study was undertaken to
assess the causes of yield variations and impact of long-term sugarcane
mono-sequencing on nutrient index (NI), microbial activity and soil
quality. About 131, 198 and 122 composite soil samples (0-20 cm depth)
were taken from cane producing Eastern zone (EZ), Central zone (CZ) and
Western zone (WZ) of Uttar Pradesh, respectively and analyzed. Long-term
sugarcane mono-sequencing depleted soil organic carbon (SOC), available
nitrogen (Na), potassium (Ka), sulphur
(Sa) and Zn as 48.9, 98.2, 39.0, 43.3 and 26.4% soil
samples falls in low categories, respectively. However, soil degradation
aggregated more in EZ soils due to acute deficiency of macro-nutrients
as well as high content of Cu, Fe and Mn in low-lying areas. Total
microbial counts (TCB, TCA, AZO), microbial biomass of carbon and
nitrogen, basal soil respiration, acid and alkaline phosphatase were
highest in WZ but Na, Pa,
Ka, Sa, FDA, β-glucosidase and urease
activity was greater in CZ soils. As a result, NI was more in CZ (2.19)
followed EZ (1.98) and WZ (1.97), but soil quality index (SQI) was found
in the order of CZ (0.795) >WZ (0.785) > EZ
(0.708). The sensitivity index was lowest in CZ soils (1.420) followed
by WZ (1.810) and EZ (1.915) indicated that WZ and EZ soils are more
preferable and sensitive to perturbations and management practices.
Na was the most vital soil quality indicator
(contributed 25.7, 26.9 and 23.7% towards SQI development in EZ, CZ and
WZ, respectively) followed by SOC, AZO and Sa. Under
nutrient deficient zone, targeted yield equations may be useful for
improving NI, SQI and sensitivity index to achieve sustainable cane
productivity and soil quality.
Key words: Sugarcane monocropping, Nutrient index, Microbial
activity, Minimum data set, Soil quality index.