Assessment of soil quality and productivity in different phases of soil erosion with the focus on land degradation neutrality in tropical humid region of India

•Productivity index based soil loss tolerance limits were estimated.•PI in different phases of erosion varies between 0.748 and 0.551.•Soil loss tolerance limit based on PI ranged from 6.67 to 12.92 Mg ha−1 year−1.•Severely eroded soils have lower microbial biomass carbon, and poor soil quality. Land area is dwindling due to degradation, both natural and anthropogenic, therefore, it is reasonable to save this important resource and put focus on achieving land degradation neutrality (LDN). An Investigation was taken to know the impact of erosion on soil physico-chemical and biological properties both in fertilized and unfertilized conditions in four phases of erosion viz., slightly eroded (0.5% slope), moderately eroded (2.5% slope), severely eroded (4.5% slope) and very severely eroded (9.5% slope). Productivity index (PI), vulnerability curve, soil loss tolerance limits (STL), soil quality index (SQI) and relative soil quality index (RSQI) were estimated for all phases of erosion. As the severity of erosion increases the soil quality and productivity index (PI) decreases. Very severely eroded soils have lower PI, SQI and RSQI as compared to slightly eroded soils. However, land use under fertilized condition have better soil quality with SQI value of 143.00 and 118.00 in slightly eroded and very severely eroded soils, respectively, compared to 126.00 and 106.00 in non-fertilized condition. Similarly, the productivity index ranged 0.748 in slightly eroded phase to 0.651 in severely eroded phase under fertilized condition. Compared to slightly eroded soil, severely and very severely eroded soils have lower microbial biomass carbon (MBC), CO2 evolution and dehydrogenase activities. Assessment of soil loss tolerance limit based on PI revealed that it ranged from 6.67 to 12.92 Mg ha−1 year−1 which implies that land degradation took place in the more eroded soils which needs higher priority in order to bringing these eroded land to degradation neutrality (LDN), and also requires suitable soil conservation interventions in different phases of erosion.