Soil Quality Changes Resulting from Long-Term Fertilizer Application Under Intensive Cropping System in Alluvial Soils

Soil quality is one of the most important factors which reveal the soil–environment functionality for identifying whether soil quality is improving, remain constant, or declining. This paper evaluated change in soil quality after 40 years of chemical fertilizer use and continuous cultivation of multiple crops (jute–rice–wheat) on alluvial soils. The concepts of relative soil quality index (RSQI) and Cumulative Rating Index (CRI) were used in the evaluation. It was observed that soil of class III reduced to class II after 20 years and to class I after 40 years of fertilizer application with manure, nitrogen, phosphorus, and potassium (NPK_100+FYM). There was a strong correlation between SQI and CRI (r = 0.82**) which showed more promising effects on soil sustainability. Significant positive relationship between ?RSQI and crop yield of jute (r = 0.89**) and wheat (r = 0.90**) was found. However, rice yield declined up to 44% of its initial yield (r = 0.20).