Highly productive rice (Oryza sativa L.) and wheat (Triticum aestivum L.) systems are crucial for millions of
rural and urban poor in the Indo-Gangetic Plains (IGP) of south Asia. Our objectives were to identify
important biological, chemical and physical indicators ofsoil quality and incorporate them into a unified
soil quality index (SQI) that could be used to help select best management practices for important
cropping systems. Two tillage, three water management and nine nutrient management treatments were
evaluated. Principal component analysis (PCA) was used to identify critical indicators and their relative
weighting for a soil quality index (SQI) that was developed using the Soil Management Assessment
Framework (SMAF). Two primary goals – productivity (PCASQI-P) and environmental protection (PCSQIEP) were established. For the productivity goal, seven indicators were evaluated for their contribution to
nutrient cycling, two for physical stability and support, and three for water relations. The environmental
quality goal used the same functions and indicators plus three additional indicators affecting filtering and
buffering, and one reflecting biodiversity and habitat. The hypothesis of the study was that the set of
sensitive indicators would vary under contrasting tillage, nutrient and water management which could
be encompassed to develop unified soil quality indices for assessing management induced changes in
rice–wheat cropping system. The results confirmed that management goal strongly influenced indicator
selection and that variations in those indicators can provide early warning against deterioration of soil
quality. Puddling and irrigating rice after three days of drainage and using no tillage and two irrigations
for wheat emerged as promising management for improved soil quality. Applying 25% of the
recommended fertilizer N dose using farm-yard manure (FYM) for rice and domestic sewage sludge for
wheat also improved soil quality. We conclude that the procedure used for indexing soil quality in this
study could not only be extended to neighboring areas of Indo-Gangetic Plain but also validated and
expanded for use in south and south–east Asian countries with similar soils and cropping systems.