To date, the sustainability of wheat ( Triticum aestivum)-soybean ( Glycine max) cropping systems has not been well assessed, especially under Indian Himalayas. Research was conducted in 1995-1996 to 2004 at Hawalbagh, India to study the effects of fertilization on yield sustainability of irrigated wheat-soybean system and on selected soil properties. The mean wheat yield under NPK+FYM (farmyard manure) treated plots was ~27% higher than NPK (2.4 Mg ha -1). The residual effect of NPK+FYM caused ~14% increase in soybean yield over NPK (2.18 Mg ha -1). Sustainable yield index values of wheat and the wheat-soybean system were greater with annual fertilizer N or NPK plots 10 Mg ha -1 FYM than NPK alone. However, benefit:cost ratio of fertilization, agronomic efficiency and partial factor productivity of applied nutrients were higher with NPK+FYM than NPK, if FYM nutrients were not considered. Soils under NPK+FYM contained higher soil organic C (SOC), total soil N, total P and Olsen-P by ~10, 42, 52 and 71%, respectively, in the 0-30 cm soil layers, compared with NPK. Non-exchangeable K decreased with time under all treatments except NPK. Total SOC in the 0-30 cm soil layer increased in all fertilized plots. Application of NPK+FYM also improved selected soil physical properties over NPK. The NPK+FYM application had better soil productivity than NPK but was not as economical as NPK if farmers had to purchase manure.
