Long-term effects of applied organic manures and inorganic fertilizers on yield and soil fertility in a wheat-rice cropping pattern

摘要

An 11 years study was conducted to investigate the effects of nine treatments of organic manures (PM: poultry manure and FYM: Farmyard manure) in combination with chemical fertilizers (NPKSZn) on crop productivity and soil fertility in a wheat-rice experiment in Bangladesh.. Organic manures had direct and residual effects on rice and wheat yields, but the effect of PM was dominant. Plots with FYM plus 75% NPKSZn produced equivalent or higher yields as 100% NPKSZn. The PM direct to wheat produced 12 %higher yield than 100% NPKSZn. After 3 crop cycles, soil pH was increased in plots with PM and unchanged in inorganic fertilizers and FYM. Percent OM (organic matter) was reduced (13 to 19%) with inorganic fertilizers and increased (7 to39%) with organic manures. Percent total N (Nitrogen) was unchanged in OM plots, but reduced in others. Available P (Phosphorus) increased dramatically in PM plots and was reduced in control plots. Exchangeable K (Potassium) was reduced in control and inorganic fertilizer treatments, but was sustained for others. After 9 years, %OM, % total N and exchangeable K were reduced further in inorganic treatment and increased in OM treatments. The soil pH increased in PM receiving treatments.